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• C# 'is' type check on struct - odd .NET 4.0 x86 optimization behavior

  - by Jacob Stanley

  Since upgrading to VS2010 I'm getting some very strange behavior with the 'is' keyword. The program below (test.cs) outputs True when compiled in debug mode (for x86) and False when compiled with optimizations on (for x86). Compiling all combinations in x64 or AnyCPU gives the expected result, True. All combinations of compiling under .NET 3.5 give the expected result, True. I'm using the batch file below (runtest.bat) to compile and test the code using various combinations of compiler .NET framework. Has anyone else seen these kind of problems under .NET 4.0? Does everyone else see the same behavior as me on their computer when running runtests.bat? #@$@#$?? Is there a fix for this? test.cs using System; public class Program { public static bool IsGuid(object item) { return item is Guid; } public static void Main() { Console.Write(IsGuid(Guid.NewGuid())); } } runtest.bat @echo off rem Usage: rem runtest -- runs with csc.exe x86 .NET 4.0 rem runtest 64 -- runs with csc.exe x64 .NET 4.0 rem runtest v3.5 -- runs with csc.exe x86 .NET 3.5 rem runtest v3.5 64 -- runs with csc.exe x64 .NET 3.5 set version=v4.0.30319 set platform=Framework for %%a in (%*) do ( if "%%a" == "64" (set platform=Framework64) if "%%a" == "v3.5" (set version=v3.5) ) echo Compiler: %platform%\%version%\csc.exe set csc="C:\Windows\Microsoft.NET\%platform%\%version%\csc.exe" set make=%csc% /nologo /nowarn:1607 test.cs rem CS1607: Referenced assembly targets a different processor rem This happens if you compile for x64 using csc32, or x86 using csc64 %make% /platform:x86 test.exe echo =^> x86 %make% /platform:x86 /optimize test.exe echo =^> x86 (Optimized) %make% /platform:x86 /debug test.exe echo =^> x86 (Debug) %make% /platform:x86 /debug /optimize test.exe echo =^> x86 (Debug + Optimized) %make% /platform:x64 test.exe echo =^> x64 %make% /platform:x64 /optimize test.exe echo =^> x64 (Optimized) %make% /platform:x64 /debug test.exe echo =^> x64 (Debug) %make% /platform:x64 /debug /optimize test.exe echo =^> x64 (Debug + Optimized) %make% /platform:AnyCPU test.exe echo =^> AnyCPU %make% /platform:AnyCPU /optimize test.exe echo =^> AnyCPU (Optimized) %make% /platform:AnyCPU /debug test.exe echo =^> AnyCPU (Debug) %make% /platform:AnyCPU /debug /optimize test.exe echo =^> AnyCPU (Debug + Optimized) Test Results When running the runtest.bat I get the following results on my Win7 x64 install. > runtest 32 v4.0 Compiler: Framework\v4.0.30319\csc.exe False => x86 False => x86 (Optimized) True => x86 (Debug) False => x86 (Debug + Optimized) True => x64 True => x64 (Optimized) True => x64 (Debug) True => x64 (Debug + Optimized) True => AnyCPU True => AnyCPU (Optimized) True => AnyCPU (Debug) True => AnyCPU (Debug + Optimized) > runtest 64 v4.0 Compiler: Framework64\v4.0.30319\csc.exe False => x86 False => x86 (Optimized) True => x86 (Debug) False => x86 (Debug + Optimized) True => x64 True => x64 (Optimized) True => x64 (Debug) True => x64 (Debug + Optimized) True => AnyCPU True => AnyCPU (Optimized) True => AnyCPU (Debug) True => AnyCPU (Debug + Optimized) > runtest 32 v3.5 Compiler: Framework\v3.5\csc.exe True => x86 True => x86 (Optimized) True => x86 (Debug) True => x86 (Debug + Optimized) True => x64 True => x64 (Optimized) True => x64 (Debug) True => x64 (Debug + Optimized) True => AnyCPU True => AnyCPU (Optimized) True => AnyCPU (Debug) True => AnyCPU (Debug + Optimized) > runtest 64 v3.5 Compiler: Framework64\v3.5\csc.exe True => x86 True => x86 (Optimized) True => x86 (Debug) True => x86 (Debug + Optimized) True => x64 True => x64 (Optimized) True => x64 (Debug) True => x64 (Debug + Optimized) True => AnyCPU True => AnyCPU (Optimized) True => AnyCPU (Debug) True => AnyCPU (Debug + Optimized) tl;dr

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• Why ????? is displayed instead of non-english characters?

  - by smhnaji

  I first created a simple HTML page that uses UTF-8 as its character encoding. Then I moved the HTML content as a view in codeigniter and it was still ok (I had used non-english characters that were ok as always) I added a simple dynamic functionality (there is a contact us form in it that emails users feedback to site admin). Please note that the characters were ok at localhost (which is a LAMP server running on Ubuntu 12.04 LTS) Strange is that when I uploaded the app to server, all persian characters are shown as ???? (For example ??? (which means Name) is shown ??? and so so...) I have not even connected to mysql or any other DBMS. It's the only page in the website (it's more an under construction page) and nothing else has been used in it. Maybe I should state that I have also used session library to thank the user after his feedback was sent to admins, nothing else. I have really no idea about the problem. UPDATE Now I can see that the problem is only with cPanel. On Directadmin I can see that everything is normal. Both Chromium and Firefox DO use UTF-8 as page's character encoding. URL is http://WEBSITE.COM/dmf/dynamic/ (dmf is the abbreviation of the project name!). There is nothing non-english in the URL. The page's code is as follows: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>??? ???????</title> <link rel="stylesheet" type="text/css" href="<?php echo base_url('template/css/style.css'); ?>" /> <!-- 1. jquery library --> <script src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"> </script> <!-- 2. flowplayer --> <script src="http://releases.flowplayer.org/5.1.1/flowplayer.min.js"></script> <!-- 3. skin --> <link rel="stylesheet" type="text/css" href="http://releases.flowplayer.org/5.1.1/skin/minimalist.css" /> </head> <body> <div id="wrapper"> <header> <h1>??? ???????</h1> </header> <section id="box-container"> <?php echo form_open('contact', "id='contact-us'"); echo form_fieldset('???? ?? ??'); if ($this->session->userdata('mailsent')) { echo '<div>??????? ???? ??? ????? ??</div>'; $this->session->sess_destroy(); } echo '<input tabindex="1" id="name-in" value="???" type="text" name="name"/> <input tabindex="2" id="mail-in" value="?????" type="email" name="email"/> <textarea tabindex="3" id="content-in" name="message">???????</textarea> <input tabindex="4" id="submit" type="submit" value="?????" />'; echo '<div class="clear"></div>'; echo form_fieldset_close(); echo form_close(); ?> <div id="sms-comp"> <h2>?????? ??????</h2> <p> <span id="comp-title">?? ??? ????</span> ???? ??????? ???? ??? </p> </div> <div id="last-program"> <h2>?????? ????? ??????</h2> <div class="flowplayer"> <video id="my_video_1" width="212" height="126" poster="<?php echo base_url('template/images/img.jpg'); ?>" controls="controls" src="http://archive.org/download/Pbtestfilemp4videotestmp4/video_test.ogv" type='video/mp4'> </video> </div> </div> <div class="clear"></div> </section> </div> <footer> ????? ? ????? : <a href="http://powered-by.com/" target="_blank">????? ???</a> </footer> </body> </html>

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• form_dropdown in codeigniter

  - by Patrick

  I'm getting a strange behaviour from form_dropdown - basically, when I reload the page after validation, the values are screwed up. this bit generates 3 drop downs with days, months and years: $days = array(0 => 'Day...'); for ($i = 1; $i <= 31; $i++) { $days[] = $i; } $months = array(0 => 'Month...', ); for ($i = 1; $i <= 12; $i++) { $months[] = $i; } $years = array(0 => 'Year...'); for ($i = 2010; $i <= 2012; $i++) { $years[$i] = $i; echo "<pre>"; print_r($years); echo "</pre>";//remove this } $selected_day = (isset($selected_day)) ? $selected_day : 0; $selected_month = (isset($selected_month)) ? $selected_month : 0; $selected_year = (isset($selected_year)) ? $selected_year : 0; echo "<p>"; echo form_label('Select date:', 'day', array('class' => 'left')); echo form_dropdown('day', $days, $selected_day, 'class="combosmall"'); echo form_dropdown('month', $months, $selected_month, 'class="combosmall"'); echo form_dropdown('year', $years, $selected_year, 'class="combosmall"'); echo "</p>"; ...and generates this: <p><label for="day" class="left">Select date:</label><select name="day" class="combosmall"> <option value="0" selected="selected">Day...</option> <option value="1">1</option> <option value="2">2</option> <option value="3">3</option> <option value="4">4</option> <option value="5">5</option> <option value="6">6</option> <option value="7">7</option> <option value="8">8</option> <option value="9">9</option> <option value="10">10</option> <option value="11">11</option> <option value="12">12</option> <option value="13">13</option> <option value="14">14</option> <option value="15">15</option> <option value="16">16</option> <option value="17">17</option> <option value="18">18</option> <option value="19">19</option> <option value="20">20</option> <option value="21">21</option> <option value="22">22</option> <option value="23">23</option> <option value="24">24</option> <option value="25">25</option> <option value="26">26</option> <option value="27">27</option> <option value="28">28</option> <option value="29">29</option> <option value="30">30</option> <option value="31">31</option> </select><select name="month" class="combosmall"> <option value="0" selected="selected">Month...</option> <option value="1">1</option> <option value="2">2</option> <option value="3">3</option> <option value="4">4</option> <option value="5">5</option> <option value="6">6</option> <option value="7">7</option> <option value="8">8</option> <option value="9">9</option> <option value="10">10</option> <option value="11">11</option> <option value="12">12</option> </select><select name="year" class="combosmall"> <option value="0" selected="selected">Year...</option> <option value="2010">2010</option> <option value="2011">2011</option> <option value="2012">2012</option> </select></p> however, when the form is reloaded after validation, the same code above generates this: <!-- days and months... --> <select name="year" class="combosmall"> <option value="0" selected="selected">Year...</option> <option value="1">2010</option> <option value="2">2011</option> <option value="3">2012</option> </select> So basically the value start from 1 instead of 2010. The same happens to days and months but obviously it doesn't make any difference in this particular case as the values would start from 1 anyway. How can I fix this - and why does it happen? edit: validation rules are: $this->load->library('form_validation'); //...rules for other fields.. $this->form_validation->set_rules('day', 'day', 'required|xss_clean'); $this->form_validation->set_rules('month', 'month', 'required|xss_clean'); $this->form_validation->set_rules('year', 'year', 'required|xss_clean'); $this->form_validation->set_error_delimiters('<p class="error">', '</p>'); //define other errors if($this->input->post('day') == 0 || $this->input->post('month') == 0 || $this->input->post('year') == 0) { $data['error'] = "Please check the date of your event."; }

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• Cocos2d-iPhone: CCSprite positions differ between Retina & non-Retina Screens

  - by bobwaycott

  I have a fairly simple app built using cocos2d-iphone, but a strange positioning problem that I've been unable to resolve. The app uses sprite sheets, and there is a Retina and non-Retina sprite sheet within the app that use the exact same artwork (except for resolution, of course). There are other artwork within the app used for CCSprites that are both standard and -hd suffixed. Within the app, a group of sprites are created when the app starts. These initially created CCSprites always position identically (and correctly) on Retina & non-Retina screens. // In method called to setup sprites when app launches // Cache & setup app sprites [[CCSpriteFrameCache sharedSpriteFrameCache] addSpriteFramesWithFile: @"sprites.plist"]; sprites = [CCSpriteBatchNode batchNodeWithFile: @"sprites.png"]; hill = [CCSprite spriteWithSpriteFrameName: @"hill.png"]; hill.position = ccp( 160, 75 ); [sprites addChild: hill z: 1]; // ... [create more sprites in same fashion] // NOTE: All sprites created here have correct positioning on Retina & non-Retina screens When a user taps the screen a certain way, a method is called that creates another group of CCSprites (on- and off-screen), animating them all in. One of these sprites, hand, is always positioned identically (and correctly) on Retina & non-Retina screens. The others (a group of clouds) successfully create & animate, but their positions are correct only on Retina displays. On a non-Retina display, each cloud has incorrect starting positions (incorrect for x, y, or sometimes both), and their ending positions after animation are also wrong. I've included the responsible code below from the on-touch method that creates the new sprites and animates them in. Again, it works as expected on a Retina display, but incorrectly on non-Retina screens. The CCSprites used are created in the same way at app-start to setup all the initial sprites in the app, which always have correct positions. // Elsewhere, in a method called on touch // Create clouds cloud1 = [CCSprite spriteWithSpriteFrameName: @"cloud_1.png"]; cloud1.position = ccp(-150, 320); cloud1.scale = 1.2f; cloud2 = [CCSprite spriteWithSpriteFrameName: @"cloud_2.png"]; cloud2.position = ccp(-150, 335); cloud2.scale = 1.3f; cloud3 = [CCSprite spriteWithSpriteFrameName: @"cloud_4.png"]; cloud3.position = ccp(-150, 400); cloud4 = [CCSprite spriteWithSpriteFrameName: @"cloud_5.png"]; cloud4.position = ccp(-150, 420); cloud5 = [CCSprite spriteWithSpriteFrameName: @"cloud_3.png"]; cloud5.position = ccp(400, 350); cloud6 = [CCSprite spriteWithSpriteFrameName: @"cloud_1.png"]; cloud6.position = ccp(400, 335); cloud6.scale = 1.1f; cloud7 = [CCSprite spriteWithSpriteFrameName: @"cloud_2.png"]; cloud7.flipY = YES; cloud7.flipX = YES; cloud7.position = ccp(400, 380); // Create hand hand = [CCSprite spriteWithSpriteFrameName:@"hand.png"]; hand.position = ccp(160, 650); [sprites addChild: cloud1 z: 10]; [sprites addChild: cloud2 z: 9]; [sprites addChild: cloud3 z: 8]; [sprites addChild: cloud4 z: 7]; [sprites addChild: cloud5 z: 6]; [sprites addChild: cloud6 z: 10]; [sprites addChild: cloud7 z: 8]; [sprites addChild: hand z: 10]; // ACTION!! [cloud1 runAction:[CCMoveTo actionWithDuration: 1.0f position: ccp(70, 320)]]; [cloud2 runAction:[CCMoveTo actionWithDuration: 1.0f position: ccp(60, 335)]]; [cloud3 runAction:[CCMoveTo actionWithDuration: 1.0f position: ccp(100, 400)]]; [cloud4 runAction:[CCMoveTo actionWithDuration: 1.0f position: ccp(80, 420)]]; [cloud5 runAction:[CCMoveTo actionWithDuration: 1.0f position: ccp(250, 350)]]; [cloud6 runAction:[CCMoveTo actionWithDuration: 1.0f position: ccp(250, 335)]]; [cloud7 runAction:[CCMoveTo actionWithDuration: 1.0f position: ccp(270, 380)]]; [hand runAction: handIn]; It may be worth mentioning that I see this incorrect positioning behavior in the iOS Simulator when running the app and switching between the standard iPhone and iPhone (Retina) hardware options. I have not been able to verify this occurs or does not occur on an actual non-Retina iPhone because I do not have one. However, this is the only time I see this odd positioning behavior occur (the incorrect results obtained after user touch), and since I'm creating all sprites in exactly the same way (i.e., [CCSprite spriteWithSpriteFrameName:] and then setting position with cpp()), I would be especially grateful for any help in tracking down why this single group of sprites are always incorrect on non-Retina screens. Thank you.

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• mysql_query arguments in PHP

  - by Chris Wilson

  I'm currently building my first database in MySQL with an interface written in PHP and am using the 'learn-by-doing' approach. The figure below illustrates my database. Table names are at the top, and the attribute names are as they appear in the real database. I am attempting to query the values of each of these attributes using the code seen below the table. I think there is something wrong with my mysql_query() function since I am able to observe the expected behaviour when my form is successfully submitted, but no search results are returned. Can anyone see where I'm going wrong here? Update 1: I've updated the question with my enter script, minus the database login credentials. <html> <head> <title>Search</title> </head> <body> <h1>Search</h1> <!--Search form - get user input from this--> <form name = "search" action = "<?=$PHP_SELF?>" method = "get"> Search for <input type = "text" name = "find" /> in <select name = "field"> <option value = "Title">Title</option> <option value = "Description">Description</option> <option value = "City">Location</option> <option value = "Company_name">Employer</option> </select> <input type = "submit" name = "search" value = "Search" /> </form> <form name = "clearsearch" action = "Search.php"> <input type = "submit" value = "Reset search" /> </form> <?php if (isset($_GET["search"])) // Check if form has been submitted correctly { // Check for a search query if($_GET["find"] == "") { echo "<p>You did not enter a search query. Please press the 'Reset search' button and try again"; exit; } echo "<h2>Search results</h2>"; ?> <table align = "left" border = "1" cellspacing = "2" cellpadding = "2"> <tr> <th><font face="Arial, Helvetica, sans-serif">No.</font></th> <th><font face="Arial, Helvetica, sans-serif">Title</font></th> <th><font face="Arial, Helvetica, sans-serif">Employer</font></th> <th><font face="Arial, Helvetica, sans-serif">Description</font></th> <th><font face="Arial, Helvetica, sans-serif">Location</font></th> <th><font face="Arial, Helvetica, sans-serif">Date Posted</font></th> <th><font face="Arial, Helvetica, sans-serif">Application Deadline</font></th> </tr> <? // Connect to the database $username=REDACTED; $password=REDACTED; $host=REDACTED; $database=REDACTED; mysql_connect($host, $username, $password); @mysql_select_db($database) or die (mysql_error()); // Perform the search $find = mysql_real_escape_string($find); $query = "SELECT job.Title, job.Description, employer.Company_name, address.City, job.Date_posted, job.Application_deadline WHERE ( Title = '{$_GET['find']}' OR Company_name = '{$_GET['find']}' OR Date_posted = '{$_GET['find']}' OR Application_deadline = '{$_GET['find']}' ) AND job.employer_id_job = employer.employer_id AND job.address_id_job = address.address_id"; if (!$query) { die ('Invalid query:' .mysql_error()); } $result = mysql_query($query); $num = mysql_numrows($result); $count = 0; while ($count < $num) { $title = mysql_result ($result, $count, "Title"); $date_posted = mysql_result ($result, $count, "Date_posted"); $application_deadline = mysql_result ($result, $count, "Application_deadline"); $description = mysql_result ($result, $count, "Description"); $company = mysql_result ($result, $count, "Company_name"); $city = mysql_result ($result, $count, "City"); ?> <tr> <td><font face = "Arial, Helvetica, sans-serif"><? echo $count + 1; ?></font></td> <td><font face = "Arial, Helvetica, sans-serif"><? echo $title; ?></font></td> <td><font face = "Arial, Helvetica, sans-serif"><? echo $company; ?></font></td> <td><font face = "Arial, Helvetica, sans-serif"><? echo $description; ?></font></td> <td><font face = "Arial, Helvetica, sans-serif"><? echo $date_posted; ?></font></td> <td><font face = "Arial, Helvetica, sans-serif"><? echo $application_deadline; ?></font></td> <td><font face = "Arial, Helvetica, sans-serif"><? echo $education_level; ?></font></td> <td><font face = "Arial, Helvetica, sans-serif"><? echo $years_of_experience; ?></font></td> <? $count ++; } } ?> </body> </html>

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• Multiple windows services in a single project = mystery

  - by Remoh

  I'm having a bizarre issue that I haven't seen before and I'm thinking it MUST be something simple that I'm not seeing in my code. I have a project with 2 windows services defined. One I've called DataSyncService, the other SubscriptionService. Both are added to the same project installer. Both use a timer control from System.Timers. If I start both services together, they seem to work fine. The timers elapse at the appropriate time and everything looks okay. However, if I start either service individually, leaving the other stopped, everything goes haywire. The timer elapses constantly and on the wrong service. In other words, if I start the DataSyncService, the SubscriptionService timer elapses over and over. ...which is obviously strange. The setup is similar to what I've done in the past so I'm really stumped. I even tried deleting both service and starting over but it doesn't seem to make a difference. At this point, I'm thinking I've made a simple error in the way I'm defining the services and my brain just won't let me see it. It must be creating some sort of threading issue that causes one service to race when the other is stopped. Here the code.... From Program.cs: static void Main() { ServiceBase[] ServicesToRun; ServicesToRun = new ServiceBase[] { new DataSyncService(), new SubscriptionService() }; ServiceBase.Run(ServicesToRun); } From ProjectInstaller.designer.cs: private void InitializeComponent() { this.serviceProcessInstaller1 = new System.ServiceProcess.ServiceProcessInstaller(); this.dataSyncInstaller = new System.ServiceProcess.ServiceInstaller(); this.subscriptionInstaller = new System.ServiceProcess.ServiceInstaller(); // // serviceProcessInstaller1 // this.serviceProcessInstaller1.Account = System.ServiceProcess.ServiceAccount.LocalSystem; this.serviceProcessInstaller1.Password = null; this.serviceProcessInstaller1.Username = null; // // dataSyncInstaller // this.dataSyncInstaller.DisplayName = "Data Sync Service"; this.dataSyncInstaller.ServiceName = "DataSyncService"; this.dataSyncInstaller.StartType = System.ServiceProcess.ServiceStartMode.Automatic; // // subscriptionInstaller // this.subscriptionInstaller.DisplayName = "Subscription Service"; this.subscriptionInstaller.ServiceName = "SubscriptionService"; this.subscriptionInstaller.StartType = System.ServiceProcess.ServiceStartMode.Automatic; // // ProjectInstaller // this.Installers.AddRange(new System.Configuration.Install.Installer[] { this.serviceProcessInstaller1, this.dataSyncInstaller, this.subscriptionInstaller}); } private System.ServiceProcess.ServiceProcessInstaller serviceProcessInstaller1; private System.ServiceProcess.ServiceInstaller dataSyncInstaller; private System.ServiceProcess.ServiceInstaller subscriptionInstaller; From DataSyncService.cs: public static readonly int _defaultInterval = 43200000; //log4net.ILog log; public DataSyncService() { InitializeComponent(); //log = LogFactory.Instance.GetLogger(this); } protected override void OnStart(string[] args) { timer1.Interval = _defaultInterval; //GetInterval(); timer1.Enabled = true; EventLog.WriteEntry("MyProj", "Data Sync Service Started", EventLogEntryType.Information); //log.Info("Data Sync Service Started"); } private void timer1_Elapsed(object sender, System.Timers.ElapsedEventArgs e) { EventLog.WriteEntry("MyProj", "Data Sync Timer Elapsed.", EventLogEntryType.Information); } private void InitializeComponent() { this.timer1 = new System.Timers.Timer(); ((System.ComponentModel.ISupportInitialize)(this.timer1)).BeginInit(); // // timer1 // this.timer1.Enabled = true; this.timer1.Elapsed += new System.Timers.ElapsedEventHandler(this.timer1_Elapsed); // // DataSyncService // this.ServiceName = "DataSyncService"; ((System.ComponentModel.ISupportInitialize)(this.timer1)).EndInit(); } From SubscriptionService: public static readonly int _defaultInterval = 300000; //log4net.ILog log; public SubscriptionService() { InitializeComponent(); } protected override void OnStart(string[] args) { timer1.Interval = _defaultInterval; //GetInterval(); timer1.Enabled = true; EventLog.WriteEntry("MyProj", "Subscription Service Started", EventLogEntryType.Information); //log.Info("Subscription Service Started"); } private void timer1_Elapsed(object sender, System.Timers.ElapsedEventArgs e) { EventLog.WriteEntry("MyProj", "Subscription Service Time Elapsed", EventLogEntryType.Information); } private void InitializeComponent() //in designer { this.timer1 = new System.Timers.Timer(); ((System.ComponentModel.ISupportInitialize)(this.timer1)).BeginInit(); // // timer1 // this.timer1.Enabled = true; this.timer1.Elapsed += new System.Timers.ElapsedEventHandler(this.timer1_Elapsed); // // SubscriptionService // this.ServiceName = "SubscriptionService"; ((System.ComponentModel.ISupportInitialize)(this.timer1)).EndInit(); } Again, the problem is that the timer1_elapsed handler runs constantly when only one of the services is started. And it's the handler on the OPPOSITE service. Anybody see anything?

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• ZF2 Vertical Form

  - by yunhasnawa

  I created a simple form in typical ZF2 application. The form class code is just a modified code provided by Zend's Album example. <?php namespace Admin\Form; use Zend\Form\Form; class CityForm extends Form { public function __construct($name = null) { parent::__construct('city'); $this->setAttribute('method', 'post'); $this->add(array( 'name' => 'id', 'attributes' => array( 'type' => 'hidden', ), )); $this->add(array( 'name' => 'name', 'attributes' => array( 'type' => 'text' ), 'options' => array( 'label' => 'Name', ), )); $this->add(array( 'name' => 'province', 'attributes' => array( 'type' => 'text' ), 'options' => array( 'label' => 'Province', ), )); $this->add(array( 'name' => 'country', 'attributes' => array( 'type' => 'text' ), 'options' => array( 'label' => 'Country', ), )); $this->add(array( 'name' => 'coordinate', 'attributes' => array( 'type' => 'text' ), 'options' => array( 'label' => 'Coordinate', ), )); $this->add(array( 'name' => 'submit', 'attributes' => array( 'type' => 'submit', 'value' => 'Save', 'id' => 'submitButton', ), )); } } And call it like this in CityController, a typical controller extends AbstractActionController: public function addAction() { $form = new CityForm(); $viewData = array( 'form' => $form ); return new ViewModel($viewData); } Finally in view I echo it like this: <?php $title = 'Add New City'; ?> <?php $this->headtitle($title); ?> <h1><?php echo $this->escapehtml($title); ?></h1> <?php $form = $this->form; ?> <?php $form->setAttribute('action', $this->url('city', array('action' => 'add'))); ?> <?php $form->prepare(); ?> <?php echo $this->form()->openTag($form); echo $this->formHidden($form->get('id')); echo $this->formRow($form->get('name')); echo $this->formRow($form->get('province')); echo $this->formRow($form->get('country')); echo $this->formRow($form->get('coordinate')); echo $this->formSubmit($form->get('submit')); echo $this->form()->closeTag(); ?> What I expected to see is a vertical form like this: But what i got is an ugly form like this: What's wrong with my code? Please help. EDIT: When I inspect element, the form generated is strange. The <input> element is inside the <label> element. <form id="city" name="city" method="post" action="/karciscus/public/admin/city/add"> <input type="hidden" value="" name="id"> <label> <span>Name</span><input type="text" value="" name="name"> </label> <label> <span>Province</span><input type="text" value="" name="province"> </label> <label> <span>Country</span><input type="text" value="" name="country"> </label> <label> <span> Coordinate</span><input type="text" value="" name="coordinate"> </label> <input type="submit" value="Save" id="submitButton" name="submit"> </form> I'm pretty sure it is the cause of my ugly rendered form. I think it is not supposedly like that. How to fix it?

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• Multi-threading does not work correctly using std::thread (C++ 11)

  - by user1364743

  I coded a small c++ program to try to understand how multi-threading works using std::thread. Here's the step of my program execution : Initialization of a 5x5 matrix of integers with a unique value '42' contained in the class 'Toto' (initialized in the main). I print the initialized 5x5 matrix. Declaration of std::vector of 5 threads. I attach all threads respectively with their task (threadTask method). Each thread will manipulate a std::vector<int> instance. I join all threads. I print the new state of my 5x5 matrix. Here's the output : 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 It should be : 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 0 0 0 0 0 1 1 1 1 1 2 2 2 2 2 3 3 3 3 3 4 4 4 4 4 Here's the code sample : #include <iostream> #include <vector> #include <thread> class Toto { public: /* ** Initialize a 5x5 matrix with the 42 value. */ void initData(void) { for (int y = 0; y < 5; y++) { std::vector<int> vec; for (int x = 0; x < 5; x++) { vec.push_back(42); } this->m_data.push_back(vec); } } /* ** Display the whole matrix. */ void printData(void) const { for (int y = 0; y < 5; y++) { for (int x = 0; x < 5; x++) { printf("%d ", this->m_data[y][x]); } printf("\n"); } printf("\n"); } /* ** Function attached to the thread (thread task). ** Replace the original '42' value by another one. */ void threadTask(std::vector<int> &list, int value) { for (int x = 0; x < 5; x++) { list[x] = value; } } /* ** Return the m_data instance propertie. */ std::vector<std::vector<int> > &getData(void) { return (this->m_data); } private: std::vector<std::vector<int> > m_data; }; int main(void) { Toto toto; toto.initData(); toto.printData(); //Display the original 5x5 matrix (first display). std::vector<std::thread> threadList(5); //Initialization of vector of 5 threads. for (int i = 0; i < 5; i++) { //Threads initializationss std::vector<int> vec = toto.getData()[i]; //Get each sub-vectors. threadList.at(i) = std::thread(&Toto::threadTask, toto, vec, i); //Each thread will be attached to a specific vector. } for (int j = 0; j < 5; j++) { threadList.at(j).join(); } toto.printData(); //Second display. getchar(); return (0); } However, in the method threadTask, if I print the variable list[x], the output is correct. I think I can't print the correct data in the main because the printData() call is in the main thread and the display in the threadTask function is correct because the method is executed in its own thread (not the main one). It's strange, it means that all threads created in a parent processes can't modified the data in this parent processes ? I think I forget something in my code. I'm really lost. Does anyone can help me, please ? Thank a lot in advance for your help.

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• Weird "?>" being displayed

  - by Jaxkr

  I have the following navigation bar script: <?php session_start(); require('includepath.inc.php'); require($include_path.'loginsysfunc.inc.php'); $current_page = $_SERVER['REQUEST_URI']; ?> <div class="navbar"> <img class="navlogo" src="logo.png"> <div class="navbutton"><a href="index.php">Home</a></div> <div class="navbutton"><a href="about.php">About</a></div> <div class="navbutton"><a href="donate.php">Donate</a></div> <?php if (loggedIn()){ ?> <div class="navusername"><a href="profile.php?user=<?php echo $_SESSION['username'];?>"><?php echo $_SESSION['username']; ?></a></div> <div class="navtoolsettings"><a href="settings.php">Settings</a></div> <div class="navtoollogout"><a href="logout.php">Log out</a> <?php } elseif ($current_page == '/login.php') { ?> <div class="navregister"><a href="register.php">Register</a></div> <?php } else { ?> <div class="navusername"><a href="login.php">Log in</a></div> <?php } ?> </div> For some reason, a strange "?" is being displayed. I am super confused, so please help. Here is includepath.inc.php (the only I reason it's there is because I am on a shared host, and I don't want to type '/home/bigdumbhash/public_html/include' everytime. But, here it is: <?php $include_path = '/home/a6595899/public_html/include/'; ?> Here is loginsysfunc.inc.php. These are functions that go with my login system to save time: <?php function valUser() { session_regenerate_id(); $_SESSION['valid'] = true; $_SESSION['username'] = $userid; echo '<meta http-equiv="refresh" content="0;URL=\'index.php\'">'; } function loggedIn() { if($_SESSION['valid'] == true) { return true; } else { return false; } } function createSalt() { $string = $string = md5(uniqid(rand(), true)); return substr($string, 0, 3); } function logout() { $_SESSION = array(); session_destroy(); echo '<meta http-equiv="refresh" content="0;URL=\'index.php\'">'; } ?> Here is the actual HTML of the page: <!DOCTYPE html> <html> <head> <link href="style.css" rel="stylesheet" type="text/css"> <title> Log in </title> </head> <body> <div class="navbar"> <img class="navlogo" src="logo.png"> <div class="navbutton"><a href="index.php">Home</a></div> <div class="navbutton"><a href="about.php">About</a></div> <div class="navbutton"><a href="donate.php">Donate</a></div> <div class="navregister"><a href="register.php">Register</a></div> </div> ?> <div class="loginbox"> <h1>Log in</h1> <form action="logingo.php" method="POST"> <input class="userpass" type="text" name="username" value="Username" onFocus="this.value='';"> <br> <input class="userpass" type="password" name="password" value="Password" onFocus="this.value='';"> <br> <input class="loginbutton" type="submit" value="Log in!"> </form> </div> </body> </html>

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• Problem with java and conditional (game of life)

  - by Muad'Dib

  Hello everybody, I'm trying to implement The Game of Life in java, as an exercise to learn this language. Unfortunately I have a problem, as I don't seem able to make this program run correctly. I implemented a torodial sum (the plane is a donut) with no problem: int SumNeighbours (int i, int j) { int value = 0; value = world[( i - 1 + row ) % row][( j - 1 + column ) % column]+world[( i - 1 + row ) % row][j]+world[( i - 1 + row ) % row][( j + 1 ) % column]; value = value + world[i][( j - 1 + column ) % column] + world[i][( j + 1 ) % column]; value = value + world[( i + 1 ) % row][( j - 1 + column ) % column] + world[( i + 1 ) % row][j]+world[ ( i+1 ) % row ][( j + 1 ) % column]; return value; } And it sums correctly when I test it: void NextWorldTest () { int count; int [][] nextWorld = new int[row][row]; nextWorld = world; for (int i=0; i<row; i++) { for (int j=0; j<column; j++) { count = SumNeighbours(i,j); System.out.print(" " + count + " "); } System.out.println(); } world=nextWorld; } Unfortunately when I add the conditions of game of life (born/death) the program stop working correctly, as it seems not able anymore to count correctly the alive cells in the neighborhood. It counts where there are none, and it doesn't count when there are some. E.g.: it doesn't count the one below some living cells. It's a very odd behaviour, and it's been giving me a headache for 3 days now... maybe I'm missing something basic about variables? Here you can find the class. void NextWorld () { int count; int [][] nextWorld = new int[row][column]; nextWorld = world; for (int i=0; i<row; i++) { for (int j=0; j<column; j++) { count = SumNeighbours(i,j); System.out.print(" " + count + " "); if ( ( world[i][j] == 0) && ( count == 3 ) ) { nextWorld[i][j] = 1; } else if ( ( world[i][j] == 1 ) && ( (count == 3) || (count == 2) )) { nextWorld[i][j] = 1; } else { nextWorld[i][j]=0; } } System.out.println(); } world=nextWorld; } } Am I doing something wrong? Below you can find the full package. package com.GaOL; public class GameWorld { int [][] world; int row; int column; public int GetRow() { return row; } public int GetColumn() { return column; } public int GetWorld (int i, int j) { return world[i][j]; } void RandomGen (int size, double p1) { double randomCell; row = size; column = size; world = new int[row][column]; for (int i = 0; i<row; i++ ) { for (int j = 0; j<column; j++ ) { randomCell=Math.random(); if (randomCell < 1-p1) { world[i][j] = 0; } else { world[i][j] = 1; } } } } void printToConsole() { double test = 0; for (int i=0; i<row; i++) { for (int j=0; j<column; j++) { if ( world[i][j] == 0 ) { System.out.print(" "); } else { System.out.print(" * "); test++; } } System.out.println(""); } System.out.println("ratio is " + test/(row*column)); } int SumNeighbours (int i, int j) { int value = 0; value = world[( i - 1 + row ) % row][( j - 1 + column ) % column]+world[( i - 1 + row ) % row][j]+world[( i - 1 + row ) % row][( j + 1 ) % column]; value = value + world[i][( j - 1 + column ) % column] + world[i][( j + 1 ) % column]; value = value + world[( i + 1 ) % row][( j - 1 + column ) % column] + world[( i + 1 ) % row][j]+world[ ( i+1 ) % row ][( j + 1 ) % column]; return value; } void NextWorldTest () { int count; int [][] nextWorld = new int[row][row]; nextWorld = world; for (int i=0; i<row; i++) { for (int j=0; j<column; j++) { count = SumNeighbours(i,j); System.out.print(" " + count + " "); } System.out.println(); } world=nextWorld; } void NextWorld () { int count; int [][] nextWorld = new int[row][column]; nextWorld = world; for (int i=0; i<row; i++) { for (int j=0; j<column; j++) { count = SumNeighbours(i,j); System.out.print(" " + count + " "); if ( ( world[i][j] == 0) && ( count == 3 ) ) { nextWorld[i][j] = 1; } else if ( ( world[i][j] == 1 ) && ( (count == 3) || (count == 2) )) { nextWorld[i][j] = 1; } else { nextWorld[i][j]=0; } } System.out.println(); } world=nextWorld; } } and here the test class: package com.GaOL; public class GameTestClass { public static void main(String[] args) { GameWorld prova = new GameWorld(); prova.RandomGen(10, 0.02); for (int i=0; i<3; i++) { prova.printToConsole(); prova.NextWorld(); } } }

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• ActiveMQ - "Cannot send, channel has already failed" every 2 seconds?

  - by quanta

  ActiveMQ 5.7.0 In the activemq.log, I'm seeing this exception every 2 seconds: 2013-11-05 13:00:52,374 | DEBUG | Transport Connection to: tcp://127.0.0.1:37501 failed: org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://127.0.0.1:37501 | org.apache.activemq.broker.TransportConnection.Transport | Async Exception Handler org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://127.0.0.1:37501 at org.apache.activemq.transport.AbstractInactivityMonitor.doOnewaySend(AbstractInactivityMonitor.java:282) at org.apache.activemq.transport.AbstractInactivityMonitor.oneway(AbstractInactivityMonitor.java:271) at org.apache.activemq.transport.TransportFilter.oneway(TransportFilter.java:85) at org.apache.activemq.transport.WireFormatNegotiator.oneway(WireFormatNegotiator.java:104) at org.apache.activemq.transport.MutexTransport.oneway(MutexTransport.java:68) at org.apache.activemq.broker.TransportConnection.dispatch(TransportConnection.java:1312) at org.apache.activemq.broker.TransportConnection.processDispatch(TransportConnection.java:838) at org.apache.activemq.broker.TransportConnection.iterate(TransportConnection.java:873) at org.apache.activemq.thread.PooledTaskRunner.runTask(PooledTaskRunner.java:129) at org.apache.activemq.thread.PooledTaskRunner$1.run(PooledTaskRunner.java:47) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:662) Due to this keyword InactivityIOException, the first thing comes to my mind is InactivityMonitor, but the strange thing is MaxInactivityDuration=30000: 2013-11-05 13:11:02,672 | DEBUG | Sending: WireFormatInfo { version=9, properties={MaxFrameSize=9223372036854775807, CacheSize=1024, CacheEnabled=true, SizePrefixDisabled=false, MaxInactivityDurationInitalDelay=10000, TcpNoDelayEnabled=true, MaxInactivityDuration=30000, TightEncodingEnabled=true, StackTraceEnabled=true}, magic=[A,c,t,i,v,e,M,Q]} | org.apache.activemq.transport.WireFormatNegotiator | ActiveMQ BrokerService[localhost] Task-2 Moreover, I also didn't see something like this: No message received since last read check for ... or: Channel was inactive for too (30000) long Do a netstat, I see these connections in TIME_WAIT state: tcp 0 0 127.0.0.1:38545 127.0.0.1:61616 TIME_WAIT - tcp 0 0 127.0.0.1:38544 127.0.0.1:61616 TIME_WAIT - tcp 0 0 127.0.0.1:38522 127.0.0.1:61616 TIME_WAIT - Here're the output when running tcpdump: Internet Protocol Version 4, Src: 127.0.0.1 (127.0.0.1), Dst: 127.0.0.1 (127.0.0.1) Version: 4 Header length: 20 bytes Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00: Not-ECT (Not ECN-Capable Transport)) 0000 00.. = Differentiated Services Codepoint: Default (0x00) .... ..00 = Explicit Congestion Notification: Not-ECT (Not ECN-Capable Transport) (0x00) Total Length: 296 Identification: 0x7b6a (31594) Flags: 0x02 (Don't Fragment) 0... .... = Reserved bit: Not set .1.. .... = Don't fragment: Set ..0. .... = More fragments: Not set Fragment offset: 0 Time to live: 64 Protocol: TCP (6) Header checksum: 0xc063 [correct] [Good: True] [Bad: False] Source: 127.0.0.1 (127.0.0.1) Destination: 127.0.0.1 (127.0.0.1) Transmission Control Protocol, Src Port: 61616 (61616), Dst Port: 54669 (54669), Seq: 1, Ack: 2, Len: 244 Source port: 61616 (61616) Destination port: 54669 (54669) [Stream index: 11] Sequence number: 1 (relative sequence number) [Next sequence number: 245 (relative sequence number)] Acknowledgement number: 2 (relative ack number) Header length: 32 bytes Flags: 0x018 (PSH, ACK) 000. .... .... = Reserved: Not set ...0 .... .... = Nonce: Not set .... 0... .... = Congestion Window Reduced (CWR): Not set .... .0.. .... = ECN-Echo: Not set .... ..0. .... = Urgent: Not set .... ...1 .... = Acknowledgement: Set .... .... 1... = Push: Set .... .... .0.. = Reset: Not set .... .... ..0. = Syn: Not set .... .... ...0 = Fin: Not set Window size value: 256 [Calculated window size: 32768] [Window size scaling factor: 128] Checksum: 0xff1c [validation disabled] [Good Checksum: False] [Bad Checksum: False] Options: (12 bytes) No-Operation (NOP) No-Operation (NOP) Timestamps: TSval 2304161892, TSecr 2304161891 Kind: Timestamp (8) Length: 10 Timestamp value: 2304161892 Timestamp echo reply: 2304161891 [SEQ/ACK analysis] [Bytes in flight: 244] Constrained Application Protocol, TID: 240, Length: 244 00.. .... = Version: 0 ..00 .... = Type: Confirmable (0) .... 0000 = Option Count: 0 Code: Unknown (0) Transaction ID: 240 Payload Content-Type: text/plain (default), Length: 240, offset: 4 Line-based text data: text/plain [truncated] \001ActiveMQ\000\000\000\t\001\000\000\000<DE>\000\000\000\t\000\fMaxFrameSize\006\177<FF><FF><FF><FF> <FF><FF><FF>\000\tCacheSize\005\000\000\004\000\000\fCacheEnabled\001\001\000\022SizePrefixDisabled\001\000\000 MaxInactivityDurationInitalDelay\006\ It is very likely a tcp port check. This is what I see when trying telnet from another host: 2013-11-05 16:12:41,071 | DEBUG | Transport Connection to: tcp://10.8.20.9:46775 failed: java.io.EOFException | org.apache.activemq.broker.TransportConnection.Transport | ActiveMQ Transport: tcp:///10.8.20.9:46775@61616 java.io.EOFException at java.io.DataInputStream.readInt(DataInputStream.java:375) at org.apache.activemq.openwire.OpenWireFormat.unmarshal(OpenWireFormat.java:275) at org.apache.activemq.transport.tcp.TcpTransport.readCommand(TcpTransport.java:229) at org.apache.activemq.transport.tcp.TcpTransport.doRun(TcpTransport.java:221) at org.apache.activemq.transport.tcp.TcpTransport.run(TcpTransport.java:204) at java.lang.Thread.run(Thread.java:662) 2013-11-05 16:12:41,071 | DEBUG | Transport Connection to: tcp://10.8.20.9:46775 failed: org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection.Transport | Async Exception Handler org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://10.8.20.9:46775 at org.apache.activemq.transport.AbstractInactivityMonitor.doOnewaySend(AbstractInactivityMonitor.java:282) at org.apache.activemq.transport.AbstractInactivityMonitor.oneway(AbstractInactivityMonitor.java:271) at org.apache.activemq.transport.TransportFilter.oneway(TransportFilter.java:85) at org.apache.activemq.transport.WireFormatNegotiator.oneway(WireFormatNegotiator.java:104) at org.apache.activemq.transport.MutexTransport.oneway(MutexTransport.java:68) at org.apache.activemq.broker.TransportConnection.dispatch(TransportConnection.java:1312) at org.apache.activemq.broker.TransportConnection.processDispatch(TransportConnection.java:838) at org.apache.activemq.broker.TransportConnection.iterate(TransportConnection.java:873) at org.apache.activemq.thread.PooledTaskRunner.runTask(PooledTaskRunner.java:129) at org.apache.activemq.thread.PooledTaskRunner$1.run(PooledTaskRunner.java:47) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:662) 2013-11-05 16:12:41,071 | DEBUG | Unregistering MBean org.apache.activemq:BrokerName=localhost,Type=Connection,ConnectorName=ope nwire,ViewType=address,Name=tcp_//10.8.20.9_46775 | org.apache.activemq.broker.jmx.ManagementContext | ActiveMQ Transport: tcp:/ //10.8.20.9:46775@61616 2013-11-05 16:12:41,073 | DEBUG | Stopping connection: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,073 | DEBUG | Stopping transport tcp:///10.8.20.9:46775@61616 | org.apache.activemq.transport.tcp.TcpTranspo rt | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,073 | DEBUG | Initialized TaskRunnerFactory[ActiveMQ Task] using ExecutorService: java.util.concurrent.Threa dPoolExecutor@23cc2a28 | org.apache.activemq.thread.TaskRunnerFactory | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,074 | DEBUG | Closed socket Socket[addr=/10.8.20.9,port=46775,localport=61616] | org.apache.activemq.transpo rt.tcp.TcpTransport | ActiveMQ Task-1 2013-11-05 16:12:41,074 | DEBUG | Forcing shutdown of ExecutorService: java.util.concurrent.ThreadPoolExecutor@23cc2a28 | org.apache.activemq.util.ThreadPoolUtils | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,074 | DEBUG | Stopped transport: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,074 | DEBUG | Connection Stopped: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,902 | DEBUG | Sending: WireFormatInfo { version=9, properties={MaxFrameSize=9223372036854775807, CacheSize=1024, CacheEnabled=true, SizePrefixDisabled=false, MaxInactivityDurationInitalDelay=10000, TcpNoDelayEnabled=true, MaxInactivityDuration=30000, TightEncodingEnabled=true, StackTraceEnabled=true}, magic=[A,c,t,i,v,e,M,Q]} | org.apache.activemq.transport.WireFormatNegotiator | ActiveMQ BrokerService[localhost] Task-5 So the question is: how can I find out the process that is trying to connect to my ActiveMQ (from localhost) every 2 seconds?

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• How to automatically remove Flash history/privacy trail? Or stop Flash from storing it?

  - by Arjan van Bentem

  Many people have heard about third-party cookies, and some browsers even block those by default. Some people may even be using Private Browsing modes. However, only few seem to realise that Adobe's Flash player also leaves a cross-browser trail on your local hard drive, and allows for sending cookie-like information back to the server, including third-party sites. And because it is a plugin, Flash does not take any of the browser's privacy settings into account. Sorry for the long post, but first some details about why using Flash raises a privacy concern, followed by the results of my tests: The Flash player keeps a cross-browser history of the domain names of the Flash-sites your computer has visited. Unlike your browser's history, this history is not limited to a certain number of days. History is also recorded while using so-called Private Browsing modes. It is stored on your hard drive (though, as described below, without going to Adobe's site you won't know what is stored). I am not sure if any date and time information is kept about each visit, but to see the domain names: right-click on some Flash content, open the settings dialog, and click the Help icon or click the Advanced button within the Privacy tab. This opens a browser to the help pages on Adobe.com, where one can click through to the Website Storage Settings panel. One can clear the existing list, but one cannot stop it from being recorded again. Flash allows for storing data on your local hard drive, using so-called Local Shared Objects (aka "Flash Cookies"). Just like HTTP cookies, this data can be sent back to the server, for tracking purposes. They are cross-browser, have no expiration date, and no user defined maximum lifetime can be set in the Flash preferences either. These not being HTTP cookies, they are (of course) not blocked by a browser's cookies preferences and are not removed when the normal HTTP cookies are deleted. Adobe has announced that version 10.1 will obey Private Browsing in most popular browsers, but unfortunately no word about also removing the data whenever normal cookies are deleted manually. And its implementation might be confusing: [..] if the browser is in normal browsing mode when the Flash Player instance is created, then that particular instance will forever be in normal browsing mode (private browsing is turned off). Accordingly, toggling private browsing on or off without refreshing the page or closing the private browsing window will not impact Flash Player. Local Shared Objects are not limited to the site you visit, and third-party storage is enabled by default. At the Global Storage Settings panel one can deselect the default Allow third-party Flash content to store data on your computer. Because of the cross-browser and expiration-less nature (and the fact that few people know about it), I feel that the cross-browser third-party Flash Cookies are more dangerous for visitor tracking than third-party normal HTTP cookies. They are even used to restore plain HTTP cookies that the user tried to delete: "All advertisers, websites and networks use cookies for targeted advertising, but cookies are under attack. According to current research they are being erased by 40% of users creating serious problems," says Mookie Tenembaum, founder of United Virtualities. "From simple frequency capping to the more sophisticated behavioral targeting, cookies are an essential part of any online ad campaign. PIE ["Persistent Identification Element"] will give publishers and third-party providers a persistent backup to cookies effectively rendering them unassailable", adds Tenembaum. [..] To justify this tracking mechanism, UV's Tenembaum said, "The user is not proficient enough in technology to know if the cookie is good or bad, or how it works." When selecting None (zero KB) for Specify the amount of disk space that website websites that you haven't yet visited can use to store information on your computer, and checking Never ask again then some sites do not work. However, the same site might work when setting it to None but without selecting Never ask again, and then choose Deny whenever prompted. Both options would result in zero KB of data being allowed, but the behaviour differs. The plugin also provides a Flash Player cache for Adobe-signed files. I guess these files are not an issue. So: how to automatically delete that information? On a Mac, one can find a settings.sol file and a folder for each visited Flash-website in: $HOME/Library/Preferences/Macromedia/Flash Player/macromedia.com/support/flashplayer/sys/ Deleting the settings.sol file and all the folders in sys, removes the trail from the settings panels. However, the actual Local Shared Ojects are elsewhere (see Wikipedia for locations on other operating systems), in a randomly named subfolder of: $HOME/Library/Preferences/Macromedia/Flash Player/#SharedObjects But then: how to remove this automatically? Simply removing the folders and the settings.sol file every now and then (like by using launchd or Windows' Task Scheduler) may interfere with active browsers. Or is it safe to assume that, given the cross-browser nature, the plugin would not care if things are removed while it is active? Only clearing during log-off may not work for those who hibernate all the time. Firefox users can install BetterPrivacy or Objection to delete the Local Shared Objects (for all others browsers as well). I don't know if that also deletes the trail of website domain names. Or: how to stop Flash from storing a history trail? Change of plans: I'm currently testing prohibiting Flash to write to its own sys and #SharedObjects folders. So far, Flash has not tried to restore permissions (though, when deleting the folders, Flash will of course recreate them). I've not encountered any problems but this may take some while to validate, using multiple browsers and sites. I've not yet found a log that reports errors. On a Mac: cd "$HOME/Library/Preferences/Macromedia/Flash Player/macromedia.com/support/flashplayer" rm -r sys/* chmod u-w sys cd "$HOME/Library/Preferences/Macromedia/Flash Player" # preserve the randomly named subfolders (only preserving the latest would suffice; see below) rm -r \#SharedObjects/*/* chmod -R u-w \#SharedObjects I guess the above chmods cannot be achieved on an old Windows system (I'm not sure about XP and Vista?). Though maybe on Windows one could replace the folders sys and #SharedObjects with dummy files with the same names? Anyone? Obviously, keeping Flash from storing those Local Shared Objects for all sites may cause problems. Some test results (Flash 10 on Mac OS X): When blocking the sys folder (even when leaving the #SharedObjects folder writable) then YouTube won't remember your volume settings while viewing multiple videos. Temporarily allowing write access to the blocked folders while visiting trusted sites (to only create folders for domains you like, maybe including references in settings.sol) solves that. This way, for YouTube, Flash could be allowed to write to sys/#s.ytimg.com and #SharedObjects/s.ytimg.com, while Flash could not create new folders for other domains. One may also need to make settings.sol read-only afterwards, or delete it again. When blocking both the sys and #SharedObjects folders, YouTube and Vimeo work fine (though they might not remember any settings). However, Bits on the Run refuses to even show the video player. This is solved by temporarily unblocking the #SharedObjects folder, to allow Flash to create a subfolder with some random name. Within this folder, it would create yet another folder for the current Flash website (content.bitsontherun.com). Removing that website-specific folder, and blocking both #SharedObjects and the randomly named subfolder, still seems to allow Bits on the Run to operate, even though it still cannot write anything to disk. So: the existence of the randomly named subfolder (even when write protected) is important for some sites. When I first found the #SharedObjects folder, it held many subfolders with random names, some created on the very same day. I wonder when Flash decides it wants a new folder, and how it determines (and remembers) that random name. For a moment I considered not blocking write access for sys and #SharedObjects, but explicitly creating read-only folders for well-known third-party tracking domains (like based on a list from, for example, AdBlock Plus). That way, any other domain could still create Local Shared Objects. But the list would be long, and the domains from AdBlock Plus are probably all third-party domains anyway, so disabling Allow third-party Flash content to store data on your computer might have the very same result. Any experience anyone? (Final notes: if the above links to the settings panels do not work in the future, then use the URL that is known to Flash player as a starting point: www.adobe.com/go/settingsmanager. See also "You Deleted Your Cookies? Think Again" at Wired.com -- which uses Flash cookies itself as well... For the very suspicious using Time Machine: you may want to exclude both folders, for each user, and remove the trace that is already on your backup.)

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• MySQL died during the night on a 12.04.1 Ubuntu

  - by Olivier

  I can't explain why, but somehow during the night, one of my MySQL running on an Ubuntu 12.04.1 box broke. The service is running but I can't login anymore (to SQL), the previous password is not working anymore. It does not looks like the server has been compromised (nothing in /var/auth.log) It looks like some automatic security upgrade (server is configured to perform those) has occured and broke something. The MySQL server has restarted a couple of times in the logs at the time errors started to happen (I get email when CRON task fail). In the logs it complains about an unset root password (I do have cron job running all day using SQL so the password was set & working for months). Anyway I can't login without password either! Do you have any idea of what could have happened? How do I get my databases back? This line looks strange : Nov 6 06:36:12 ns398758 mysqld_safe[6676]: ERROR: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'ALTER TABLE user ADD column Show_view_priv enum('N','Y') CHARACTER SET utf8 NOT ' at line 1 Here is the full log below : Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: PLEASE REMEMBER TO SET A PASSWORD FOR THE MySQL root USER ! Nov 6 06:36:06 ns398758 mysqld_safe[6586]: To do so, start the server, then issue the following commands: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: /usr/bin/mysqladmin -u root password 'new-password' Nov 6 06:36:06 ns398758 mysqld_safe[6586]: /usr/bin/mysqladmin -u root -h ns398758.ovh.net password 'new-password' Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Alternatively you can run: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: /usr/bin/mysql_secure_installation Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: which will also give you the option of removing the test Nov 6 06:36:06 ns398758 mysqld_safe[6586]: databases and anonymous user created by default. This is Nov 6 06:36:06 ns398758 mysqld_safe[6586]: strongly recommended for production servers. Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: See the manual for more instructions. Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Please report any problems with the /usr/scripts/mysqlbug script! Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 [Note] Plugin 'FEDERATED' is disabled. Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 InnoDB: The InnoDB memory heap is disabled Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 InnoDB: Mutexes and rw_locks use GCC atomic builtins Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 InnoDB: Compressed tables use zlib 1.2.3.4 Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 InnoDB: Initializing buffer pool, size = 128.0M Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 InnoDB: Completed initialization of buffer pool Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 InnoDB: highest supported file format is Barracuda. Nov 6 06:36:07 ns398758 mysqld_safe[6632]: 121106 6:36:07 InnoDB: Waiting for the background threads to start Nov 6 06:36:08 ns398758 mysqld_safe[6632]: 121106 6:36:08 InnoDB: 1.1.8 started; log sequence number 29276459701 Nov 6 06:36:08 ns398758 mysqld_safe[6632]: 121106 6:36:08 InnoDB: Starting shutdown... Nov 6 06:36:09 ns398758 mysqld_safe[6632]: 121106 6:36:09 InnoDB: Shutdown completed; log sequence number 29276459701 Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 [Note] Plugin 'FEDERATED' is disabled. Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: The InnoDB memory heap is disabled Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: Mutexes and rw_locks use GCC atomic builtins Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: Compressed tables use zlib 1.2.3.4 Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: Initializing buffer pool, size = 128.0M Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: Completed initialization of buffer pool Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: highest supported file format is Barracuda. Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: Waiting for the background threads to start Nov 6 06:36:12 ns398758 mysqld_safe[6676]: 121106 6:36:12 InnoDB: 1.1.8 started; log sequence number 29276459701 Nov 6 06:36:12 ns398758 mysqld_safe[6676]: ERROR: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'ALTER TABLE user ADD column Show_view_priv enum('N','Y') CHARACTER SET utf8 NOT ' at line 1 Nov 6 06:36:12 ns398758 mysqld_safe[6676]: 121106 6:36:12 [ERROR] Aborting Nov 6 06:36:12 ns398758 mysqld_safe[6676]: Nov 6 06:36:12 ns398758 mysqld_safe[6676]: 121106 6:36:12 InnoDB: Starting shutdown... Nov 6 06:36:13 ns398758 mysqld_safe[6676]: 121106 6:36:13 InnoDB: Shutdown completed; log sequence number 29276459701 Nov 6 06:36:13 ns398758 mysqld_safe[6676]: 121106 6:36:13 [Note] /usr/sbin/mysqld: Shutdown complete Nov 6 06:36:13 ns398758 mysqld_safe[6676]: Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 [Note] Plugin 'FEDERATED' is disabled. Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: The InnoDB memory heap is disabled Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: Mutexes and rw_locks use GCC atomic builtins Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: Compressed tables use zlib 1.2.3.4 Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: Initializing buffer pool, size = 128.0M Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: Completed initialization of buffer pool Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: highest supported file format is Barracuda. Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: Waiting for the background threads to start Nov 6 06:36:14 ns398758 mysqld_safe[6697]: 121106 6:36:14 InnoDB: 1.1.8 started; log sequence number 29276459701 Nov 6 06:36:14 ns398758 mysqld_safe[6697]: 121106 6:36:14 InnoDB: Starting shutdown... Nov 6 06:36:15 ns398758 mysqld_safe[6697]: 121106 6:36:15 InnoDB: Shutdown completed; log sequence number 29276459701 Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 [Note] Plugin 'FEDERATED' is disabled. Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: The InnoDB memory heap is disabled Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: Mutexes and rw_locks use GCC atomic builtins Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: Compressed tables use zlib 1.2.3.4 Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: Initializing buffer pool, size = 128.0M Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: Completed initialization of buffer pool Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: highest supported file format is Barracuda. Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: Waiting for the background threads to start Nov 6 06:36:16 ns398758 mysqld_safe[6718]: 121106 6:36:16 InnoDB: 1.1.8 started; log sequence number 29276459701 Nov 6 06:36:16 ns398758 mysqld_safe[6718]: ERROR: 1050 Table 'plugin' already exists Nov 6 06:36:16 ns398758 mysqld_safe[6718]: 121106 6:36:16 [ERROR] Aborting Nov 6 06:36:16 ns398758 mysqld_safe[6718]: Nov 6 06:36:16 ns398758 mysqld_safe[6718]: 121106 6:36:16 InnoDB: Starting shutdown... Nov 6 06:36:17 ns398758 mysqld_safe[6718]: 121106 6:36:17 InnoDB: Shutdown completed; log sequence number 29276459701 Nov 6 06:36:17 ns398758 mysqld_safe[6718]: 121106 6:36:17 [Note] /usr/sbin/mysqld: Shutdown complete Nov 6 06:36:17 ns398758 mysqld_safe[6718]: Nov 6 06:36:19 ns398758 /etc/mysql/debian-start[6816]: Upgrading MySQL tables if necessary. Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: /usr/bin/mysql_upgrade: the '--basedir' option is always ignored Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: Looking for 'mysql' as: /usr/bin/mysql Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: Looking for 'mysqlcheck' as: /usr/bin/mysqlcheck Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: Running 'mysqlcheck' with connection arguments: '--port=3306' '--socket=/var/run/mysqld/mysqld.sock' '--host=localhost' '--socket=/var/run/mysqld/mysqld.sock' '--host=localhost' '--socket=/var/run/mysqld/mysqld.sock' Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: Running 'mysqlcheck' with connection arguments: '--port=3306' '--socket=/var/run/mysqld/mysqld.sock' '--host=localhost' '--socket=/var/run/mysqld/mysqld.sock' '--host=localhost' '--socket=/var/run/mysqld/mysqld.sock' Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: col_digitas.acos OK Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: col_digitas.aros OK ...

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• Why load increase ,ssd iops increase but cpu iowait decrease?

  - by mq44944

  There is a strange thing on my server which has a mysql running on it. The QPS is more than 4000 but TPS is less than 20. The server load is more than 80 and cpu usr is more than 86% but iowait is less than 8%. The disk iops is more than 16000 and util of disk is more than 99%. When the QPS decreases, the load decreases, the cpu iowait increases. I can't catch this! root@mypc # dmidecode | grep "Product Name" Product Name: PowerEdge R510 Product Name: 084YMW root@mypc # megacli -PDList -aALL |grep "Inquiry Data" Inquiry Data: SEAGATE ST3600057SS ES656SL316PT Inquiry Data: SEAGATE ST3600057SS ES656SL30THV Inquiry Data: ATA INTEL SSDSA2CW300362CVPR201602A6300EGN Inquiry Data: ATA INTEL SSDSA2CW300362CVPR2044037K300EGN Inquiry Data: ATA INTEL SSDSA2CW300362CVPR204402PX300EGN Inquiry Data: ATA INTEL SSDSA2CW300362CVPR204403WN300EGN Inquiry Data: ATA INTEL SSDSA2CW300362CVPR202000HU300EGN Inquiry Data: ATA INTEL SSDSA2CW300362CVPR202001E7300EGN Inquiry Data: ATA INTEL SSDSA2CW300362CVPR204402WE300EGN Inquiry Data: ATA INTEL SSDSA2CW300362CVPR204404E5300EGN Inquiry Data: ATA INTEL SSDSA2CW300362CVPR204401QF300EGN Inquiry Data: ATA INTEL SSDSA2CW300362CVPR20450001300EGN the mysql data files lie on the ssd disks which are organizaed using RAID 10. root@mypc # megacli -LDInfo -L1 -a0 Adapter 0 -- Virtual Drive Information: Virtual Disk: 1 (Target Id: 1) Name: RAID Level: Primary-1, Secondary-0, RAID Level Qualifier-0 Size:1427840MB State: Optimal Stripe Size: 64kB Number Of Drives:2 Span Depth:5 Default Cache Policy: WriteThrough, ReadAheadNone, Direct, No Write Cache if Bad BBU Current Cache Policy: WriteThrough, ReadAheadNone, Direct, No Write Cache if Bad BBU Access Policy: Read/Write Disk Cache Policy: Disk's Default Exit Code: 0x00 -------- -----load-avg---- ---cpu-usage--- ---swap--- -------------------------io-usage----------------------- -QPS- -TPS- -Hit%- time | 1m 5m 15m |usr sys idl iow| si so| r/s w/s rkB/s wkB/s queue await svctm %util| ins upd del sel iud| lor hit| 09:05:29|79.80 64.49 42.00| 82 7 6 5| 0 0|16421.1 10.6262705.9 85.2 8.3 0.5 0.1 99.5| 0 0 0 3968 0| 495482 96.58| 09:05:30|79.80 64.49 42.00| 79 7 8 6| 0 0|15907.4 230.6254409.7 6357.5 8.4 0.5 0.1 98.5| 0 0 0 4195 0| 496434 96.68| 09:05:31|81.34 65.07 42.31| 81 7 7 5| 0 0|16198.7 8.6259029.2 99.8 8.1 0.5 0.1 99.3| 0 0 0 4220 0| 508983 96.70| 09:05:32|81.34 65.07 42.31| 82 7 5 5| 0 0|16746.6 8.7267853.3 92.4 8.5 0.5 0.1 99.4| 0 0 0 4084 0| 503834 96.54| 09:05:33|81.34 65.07 42.31| 81 7 6 5| 0 0|16498.7 9.6263856.8 92.3 8.0 0.5 0.1 99.3| 0 0 0 4030 0| 507051 96.60| 09:05:34|81.34 65.07 42.31| 80 8 7 6| 0 0|16328.4 11.5261101.6 95.8 8.1 0.5 0.1 98.3| 0 0 0 4119 0| 504409 96.63| 09:05:35|81.31 65.33 42.52| 82 7 6 5| 0 0|16374.0 8.7261921.9 92.5 8.1 0.5 0.1 99.7| 0 0 0 4127 0| 507279 96.66| 09:05:36|81.31 65.33 42.52| 81 8 6 5| 0 0|16496.2 8.6263832.0 84.5 8.5 0.5 0.1 99.2| 0 0 0 4100 0| 505054 96.59| 09:05:37|81.31 65.33 42.52| 82 8 6 4| 0 0|16239.4 9.6259768.8 84.3 8.0 0.5 0.1 99.1| 0 0 0 4273 0| 510621 96.72| 09:05:38|81.31 65.33 42.52| 81 7 6 5| 0 0|16349.6 8.7261439.2 81.4 8.2 0.5 0.1 98.9| 0 0 0 4171 0| 510145 96.67| 09:05:39|81.31 65.33 42.52| 82 7 6 5| 0 0|16116.8 8.7257667.6 96.5 8.0 0.5 0.1 99.1| 0 0 0 4348 0| 513093 96.74| 09:05:40|79.60 65.24 42.61| 79 7 7 7| 0 0|16154.2 242.9258390.4 6388.4 8.5 0.5 0.1 99.0| 0 0 0 4033 0| 507244 96.70| 09:05:41|79.60 65.24 42.61| 79 7 8 6| 0 0|16583.1 21.2265129.6 173.5 8.2 0.5 0.1 99.1| 0 0 0 3995 0| 501474 96.57| 09:05:42|79.60 65.24 42.61| 81 8 6 5| 0 0|16281.0 9.7260372.2 69.5 8.3 0.5 0.1 98.7| 0 0 0 4221 0| 509322 96.70| 09:05:43|79.60 65.24 42.61| 80 7 7 6| 0 0|16355.3 8.7261515.5 104.3 8.2 0.5 0.1 99.6| 0 0 0 4087 0| 502052 96.62| -------- -----load-avg---- ---cpu-usage--- ---swap--- -------------------------io-usage----------------------- -QPS- -TPS- -Hit%- time | 1m 5m 15m |usr sys idl iow| si so| r/s w/s rkB/s wkB/s queue await svctm %util| ins upd del sel iud| lor hit| 09:05:44|79.60 65.24 42.61| 83 7 5 4| 0 0|16469.4 11.6263387.0 138.8 8.2 0.5 0.1 98.7| 0 0 0 4292 0| 509979 96.65| 09:05:45|79.07 65.37 42.77| 80 7 6 6| 0 0|16659.5 9.7266478.7 85.0 8.4 0.5 0.1 98.5| 0 0 0 3899 0| 496234 96.54| 09:05:46|79.07 65.37 42.77| 78 7 7 8| 0 0|16752.9 8.7267921.8 97.1 8.4 0.5 0.1 98.9| 0 0 0 4126 0| 508300 96.57| 09:05:47|79.07 65.37 42.77| 82 7 6 5| 0 0|16657.2 9.6266439.3 84.3 8.3 0.5 0.1 98.9| 0 0 0 4086 0| 502171 96.57| 09:05:48|79.07 65.37 42.77| 79 8 6 6| 0 0|16814.5 8.7268924.1 77.6 8.5 0.5 0.1 99.0| 0 0 0 4059 0| 499645 96.52| 09:05:49|79.07 65.37 42.77| 81 7 6 5| 0 0|16553.0 6.8264708.6 42.5 8.3 0.5 0.1 99.4| 0 0 0 4249 0| 501623 96.60| 09:05:50|79.63 65.71 43.01| 79 7 7 7| 0 0|16295.1 246.9260475.0 6442.4 8.7 0.5 0.1 99.1| 0 0 0 4231 0| 511032 96.70| 09:05:51|79.63 65.71 43.01| 80 7 6 6| 0 0|16568.9 8.7264919.7 104.7 8.3 0.5 0.1 99.7| 0 0 0 4272 0| 517177 96.68| 09:05:53|79.63 65.71 43.01| 79 7 7 6| 0 0|16539.0 8.6264502.9 87.6 8.4 0.5 0.1 98.9| 0 0 0 3992 0| 496728 96.52| 09:05:54|79.63 65.71 43.01| 79 7 7 7| 0 0|16527.5 11.6264363.6 92.6 8.5 0.5 0.1 98.8| 0 0 0 4045 0| 502944 96.59| 09:05:55|79.63 65.71 43.01| 80 7 7 6| 0 0|16374.7 12.5261687.2 134.9 8.6 0.5 0.1 99.2| 0 0 0 4143 0| 507006 96.66| 09:05:56|76.05 65.20 42.96| 77 8 8 8| 0 0|16464.9 9.6263314.3 111.9 8.5 0.5 0.1 98.9| 0 0 0 4250 0| 505417 96.64| 09:05:57|76.05 65.20 42.96| 79 7 6 7| 0 0|16460.1 8.8263283.2 93.4 8.3 0.5 0.1 98.8| 0 0 0 4294 0| 508168 96.66| 09:05:58|76.05 65.20 42.96| 80 7 7 7| 0 0|16176.5 9.6258762.1 127.3 8.3 0.5 0.1 98.9| 0 0 0 4160 0| 509349 96.72| 09:05:59|76.05 65.20 42.96| 75 7 9 10| 0 0|16522.0 10.7264274.6 93.1 8.6 0.5 0.1 97.5| 0 0 0 4034 0| 492623 96.51| -------- -----load-avg---- ---cpu-usage--- ---swap--- -------------------------io-usage----------------------- -QPS- -TPS- -Hit%- time | 1m 5m 15m |usr sys idl iow| si so| r/s w/s rkB/s wkB/s queue await svctm %util| ins upd del sel iud| lor hit| 09:06:00|76.05 65.20 42.96| 79 7 7 7| 0 0|16369.6 21.2261867.3 262.5 8.4 0.5 0.1 98.9| 0 0 0 4305 0| 494509 96.59| 09:06:01|75.33 65.23 43.09| 73 6 9 12| 0 0|15864.0 209.3253685.4 6238.0 10.0 0.6 0.1 98.7| 0 0 0 3913 0| 483480 96.62| 09:06:02|75.33 65.23 43.09| 73 7 8 12| 0 0|15854.7 12.7253613.2 93.6 11.0 0.7 0.1 99.0| 0 0 0 4271 0| 483771 96.64| 09:06:03|75.33 65.23 43.09| 75 7 9 9| 0 0|16074.8 8.7257104.3 81.7 8.1 0.5 0.1 98.5| 0 0 0 4060 0| 480701 96.55| 09:06:04|75.33 65.23 43.09| 76 7 8 9| 0 0|16221.7 9.7259500.1 139.4 8.1 0.5 0.1 97.6| 0 0 0 3953 0| 486774 96.56| 09:06:05|74.98 65.33 43.24| 78 7 8 8| 0 0|16330.7 8.7261166.5 85.3 8.2 0.5 0.1 98.5| 0 0 0 3957 0| 481775 96.53| 09:06:06|74.98 65.33 43.24| 75 7 9 9| 0 0|16093.7 11.7257436.1 93.7 8.2 0.5 0.1 99.2| 0 0 0 3938 0| 489251 96.60| 09:06:07|74.98 65.33 43.24| 75 7 5 13| 0 0|15758.9 19.2251989.4 188.2 14.7 0.9 0.1 99.7| 0 0 0 4140 0| 494738 96.70| 09:06:08|74.98 65.33 43.24| 69 7 10 15| 0 0|16166.3 8.7258474.9 81.2 8.9 0.5 0.1 98.7| 0 0 0 3993 0| 487162 96.58| 09:06:09|74.98 65.33 43.24| 74 7 9 10| 0 0|16071.0 8.7257010.9 93.3 8.2 0.5 0.1 99.2| 0 0 0 4098 0| 491557 96.61| 09:06:10|70.98 64.66 43.14| 71 7 9 12| 0 0|15549.6 216.1248701.1 6188.7 8.3 0.5 0.1 97.8| 0 0 0 3879 0| 480832 96.66| 09:06:11|70.98 64.66 43.14| 71 7 10 13| 0 0|16233.7 22.4259568.1 257.1 8.2 0.5 0.1 99.2| 0 0 0 4088 0| 493200 96.62| 09:06:12|70.98 64.66 43.14| 78 7 8 7| 0 0|15932.4 10.6254779.5 108.1 8.1 0.5 0.1 98.6| 0 0 0 4168 0| 489838 96.63| 09:06:13|70.98 64.66 43.14| 71 8 9 12| 0 0|16255.9 11.5259902.3 103.9 8.3 0.5 0.1 98.0| 0 0 0 3874 0| 481246 96.52| 09:06:14|70.98 64.66 43.14| 60 6 16 18| 0 0|15621.0 9.7249826.1 81.9 8.0 0.5 0.1 99.3| 0 0 0 3956 0| 480278 96.65|

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• Fedora 16 can connect to samba share using smbclient but not in nautilus 3.2.1

  - by Nathan Jones

  I have a machine running Ubuntu 11.10 Server acting as a Samba server to share my home directory. Everything works fine on my Windows 7 machine, but on my Fedora 16 laptop, if I use Nautilus to try to access the share using smb://192.168.0.8/nathan in the location bar, it just has the loading cursor and does nothing. It never shows any errors, nothing. Using smbclient works just fine, but I'd like to get it working in Nautilus. I know that there can be problems with SELinux and Samba, so I created a file called booleans.local that contains samba_enable_home_dirs=1. My smb.conf file looks like this: # For Unix password sync to work on a Debian GNU/Linux system, the following # parameters must be set (thanks to Ian Kahan <<[email protected]> for # sending the correct chat script for the passwd program in Debian Sarge). passwd program = /usr/bin/passwd %u passwd chat = *Enter\snew\s*\spassword:* %n\n *Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* . # This boolean controls whether PAM will be used for password changes # when requested by an SMB client instead of the program listed in # 'passwd program'. The default is 'no'. pam password change = yes # This option controls how unsuccessful authentication attempts are mapped # to anonymous connections map to guest = bad user ########## Domains ########### # Is this machine able to authenticate users. Both PDC and BDC # must have this setting enabled. If you are the BDC you must # change the 'domain master' setting to no # ; domain logons = yes # # The following setting only takes effect if 'domain logons' is set # It specifies the location of the user's profile directory # from the client point of view) # The following required a [profiles] share to be setup on the # samba server (see below) ; logon path = \\%N\profiles\%U # Another common choice is storing the profile in the user's home directory # (this is Samba's default) # logon path = \\%N\%U\profile # The following setting only takes effect if 'domain logons' is set # It specifies the location of a user's home directory (from the client # point of view) ; logon drive = H: # logon home = \\%N\%U # The following setting only takes effect if 'domain logons' is set # It specifies the script to run during logon. The script must be stored # in the [netlogon] share # NOTE: Must be store in 'DOS' file format convention ; logon script = logon.cmd # This allows Unix users to be created on the domain controller via the SAMR # RPC pipe. The example command creates a user account with a disabled Unix # password; please adapt to your needs ; add user script = /usr/sbin/adduser --quiet --disabled-password --gecos "" %u # This allows machine accounts to be created on the domain controller via the # SAMR RPC pipe. # The following assumes a "machines" group exists on the system ; add machine script = /usr/sbin/useradd -g machines -c "%u machine account" -d /var/lib/samba -s /bin/false %u # This allows Unix groups to be created on the domain controller via the SAMR # RPC pipe. ; add group script = /usr/sbin/addgroup --force-badname %g ########## Printing ########## # If you want to automatically load your printer list rather # than setting them up individually then you'll need this # load printers = yes # lpr(ng) printing. You may wish to override the location of the # printcap file ; printing = bsd ; printcap name = /etc/printcap # CUPS printing. See also the cupsaddsmb(8) manpage in the # cupsys-client package. ; printing = cups ; printcap name = cups ############ Misc ############ # Using the following line enables you to customise your configuration # on a per machine basis. The %m gets replaced with the netbios name # of the machine that is connecting ; include = /home/samba/etc/smb.conf.%m # Most people will find that this option gives better performance. # See smb.conf(5) and /usr/share/doc/samba-doc/htmldocs/Samba3-HOWTO/speed.html # for details # You may want to add the following on a Linux system: # SO_RCVBUF=8192 SO_SNDBUF=8192 # socket options = TCP_NODELAY # The following parameter is useful only if you have the linpopup package # installed. The samba maintainer and the linpopup maintainer are # working to ease installation and configuration of linpopup and samba. ; message command = /bin/sh -c '/usr/bin/linpopup "%f" "%m" %s; rm %s' & # Domain Master specifies Samba to be the Domain Master Browser. If this # machine will be configured as a BDC (a secondary logon server), you # must set this to 'no'; otherwise, the default behavior is recommended. # domain master = auto # Some defaults for winbind (make sure you're not using the ranges # for something else.) ; idmap uid = 10000-20000 ; idmap gid = 10000-20000 ; template shell = /bin/bash # The following was the default behaviour in sarge, # but samba upstream reverted the default because it might induce # performance issues in large organizations. # See Debian bug #368251 for some of the consequences of *not* # having this setting and smb.conf(5) for details. ; winbind enum groups = yes ; winbind enum users = yes # Setup usershare options to enable non-root users to share folders # with the net usershare command. # Maximum number of usershare. 0 (default) means that usershare is disabled. ; usershare max shares = 100 # Allow users who've been granted usershare privileges to create # public shares, not just authenticated ones usershare allow guests = yes #======================= Share Definitions ======================= # Un-comment the following (and tweak the other settings below to suit) # to enable the default home directory shares. This will share each # user's home director as \\server\username [homes] comment = Home Directories browseable = yes # By default, the home directories are exported read-only. Change the # next parameter to 'no' if you want to be able to write to them. read only = no # File creation mask is set to 0700 for security reasons. If you want to # create files with group=rw permissions, set next parameter to 0775. ; create mask = 0775 # Directory creation mask is set to 0700 for security reasons. If you want to # create dirs. with group=rw permissions, set next parameter to 0775. ; directory mask = 0775 # By default, \\server\username shares can be connected to by anyone # with access to the samba server. Un-comment the following parameter # to make sure that only "username" can connect to \\server\username # The following parameter makes sure that only "username" can connect # # This might need tweaking when using external authentication schemes valid users = %S # Un-comment the following and create the netlogon directory for Domain Logons # (you need to configure Samba to act as a domain controller too.) ;[netlogon] ; comment = Network Logon Service ; path = /home/samba/netlogon ; guest ok = yes ; read only = yes # Un-comment the following and create the profiles directory to store # users profiles (see the "logon path" option above) # (you need to configure Samba to act as a domain controller too.) # The path below should be writable by all users so that their # profile directory may be created the first time they log on ;[profiles] ; comment = Users profiles ; path = /home/samba/profiles ; guest ok = no ; browseable = no ; create mask = 0600 ; directory mask = 0700 [printers] comment = All Printers browseable = no path = /var/spool/samba printable = yes guest ok = no read only = no create mask = 0700 # Windows clients look for this share name as a source of downloadable # printer drivers [print$] comment = Printer Drivers path = /var/lib/samba/printers browseable = yes read only = yes guest ok = no # Uncomment to allow remote administration of Windows print drivers. # You may need to replace 'lpadmin' with the name of the group your # admin users are members of. # Please note that you also need to set appropriate Unix permissions # to the drivers directory for these users to have write rights in it ; write list = root, @lpadmin # A sample share for sharing your CD-ROM with others. ;[cdrom] ; comment = Samba server's CD-ROM ; read only = yes ; locking = no ; path = /cdrom ; guest ok = yes # The next two parameters show how to auto-mount a CD-ROM when the # cdrom share is accesed. For this to work /etc/fstab must contain # an entry like this: # # /dev/scd0 /cdrom iso9660 defaults,noauto,ro,user 0 0 # # The CD-ROM gets unmounted automatically after the connection to the # # If you don't want to use auto-mounting/unmounting make sure the CD # is mounted on /cdrom # ; preexec = /bin/mount /cdrom ; postexec = /bin/umount /cdrom smbusers: <nathan> = <"nathan"> Any help would be very much appreciated! Thanks!

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• SElinux process killed while trying to set boolean

  - by Antonio

  I've got a strange problem. I can not allow apache to connect to database at my CentOC 6.4 box: [root@centos6 ~]# setsebool -P httpd_can_network_connect on Killed [root@centos6 ~]# sestatus -b | grep httpd_can_network_connect httpd_can_network_connect off httpd_can_network_connect_cobbler off httpd_can_network_connect_db off I watched log file, but there was no log messages: tail -f /var/log/audit/audit.log UPDATE: There are some information in /var/log/messages: Nov 9 19:07:16 vs302 kernel: setsebool invoked oom-killer: gfp_mask=0x280da, order=0, oom_adj=0, oom_score_adj=0 Nov 9 19:07:16 vs302 kernel: setsebool cpuset=/ mems_allowed=0 Nov 9 19:07:16 vs302 kernel: Pid: 1660, comm: setsebool Not tainted 2.6.32-358.23.2.el6.x86_64 #1 Nov 9 19:07:16 vs302 kernel: Call Trace: Nov 9 19:07:16 vs302 kernel: [<ffffffff810cb641>] ? cpuset_print_task_mems_allowed+0x91/0xb0 Nov 9 19:07:16 vs302 kernel: [<ffffffff8111ce40>] ? dump_header+0x90/0x1b0 Nov 9 19:07:16 vs302 kernel: [<ffffffff8111d2c2>] ? oom_kill_process+0x82/0x2a0 Nov 9 19:07:16 vs302 kernel: [<ffffffff8111d201>] ? select_bad_process+0xe1/0x120 Nov 9 19:07:16 vs302 kernel: [<ffffffff8111d700>] ? out_of_memory+0x220/0x3c0 Nov 9 19:07:16 vs302 kernel: [<ffffffff8112c3dc>] ? __alloc_pages_nodemask+0x8ac/0x8d0 Nov 9 19:07:16 vs302 kernel: [<ffffffff81160d6a>] ? alloc_pages_vma+0x9a/0x150 Nov 9 19:07:16 vs302 kernel: [<ffffffff81143f0b>] ? handle_pte_fault+0x76b/0xb50 Nov 9 19:07:16 vs302 kernel: [<ffffffff81228664>] ? task_has_capability+0xb4/0x110 Nov 9 19:07:16 vs302 kernel: [<ffffffff81004a49>] ? __raw_callee_save_xen_pmd_val+0x11/0x1e Nov 9 19:07:16 vs302 kernel: [<ffffffff8114452a>] ? handle_mm_fault+0x23a/0x310 Nov 9 19:07:16 vs302 kernel: [<ffffffff811485b6>] ? vma_adjust+0x556/0x5e0 Nov 9 19:07:16 vs302 kernel: [<ffffffff810474e9>] ? __do_page_fault+0x139/0x480 Nov 9 19:07:16 vs302 kernel: [<ffffffff81148b8a>] ? vma_merge+0x29a/0x3e0 Nov 9 19:07:16 vs302 kernel: [<ffffffff81149fdc>] ? do_brk+0x26c/0x350 Nov 9 19:07:16 vs302 kernel: [<ffffffff8100ba1d>] ? retint_restore_args+0x5/0x6 Nov 9 19:07:16 vs302 kernel: [<ffffffff81513bfe>] ? do_page_fault+0x3e/0xa0 Nov 9 19:07:16 vs302 kernel: [<ffffffff81510fb5>] ? page_fault+0x25/0x30 Nov 9 19:07:16 vs302 kernel: Mem-Info: Nov 9 19:07:16 vs302 kernel: Node 0 DMA per-cpu: Nov 9 19:07:16 vs302 kernel: CPU 0: hi: 0, btch: 1 usd: 0 Nov 9 19:07:16 vs302 kernel: Node 0 DMA32 per-cpu: Nov 9 19:07:16 vs302 kernel: CPU 0: hi: 186, btch: 31 usd: 30 Nov 9 19:07:16 vs302 kernel: active_anon:132249 inactive_anon:46 isolated_anon:0 Nov 9 19:07:16 vs302 kernel: active_file:56 inactive_file:59 isolated_file:0 Nov 9 19:07:16 vs302 kernel: unevictable:0 dirty:2 writeback:0 unstable:0 Nov 9 19:07:16 vs302 kernel: free:1369 slab_reclaimable:1774 slab_unreclaimable:11588 Nov 9 19:07:16 vs302 kernel: mapped:54 shmem:48 pagetables:1211 bounce:0 Nov 9 19:07:16 vs302 kernel: Node 0 DMA free:2440kB min:72kB low:88kB high:108kB active_anon:12156kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:14648kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:24kB slab_unreclaimable:8kB kernel_stack:0kB pagetables:16kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? yes Nov 9 19:07:16 vs302 kernel: lowmem_reserve[]: 0 590 590 590 Nov 9 19:07:16 vs302 kernel: Node 0 DMA32 free:3036kB min:3072kB low:3840kB high:4608kB active_anon:516840kB inactive_anon:184kB active_file:224kB inactive_file:236kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:604988kB mlocked:0kB dirty:8kB writeback:0kB mapped:216kB shmem:192kB slab_reclaimable:7072kB slab_unreclaimable:46344kB kernel_stack:880kB pagetables:4828kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:128 all_unreclaimable? no Nov 9 19:07:16 vs302 kernel: lowmem_reserve[]: 0 0 0 0 Nov 9 19:07:16 vs302 kernel: Node 0 DMA: 0*4kB 1*8kB 0*16kB 0*32kB 0*64kB 1*128kB 1*256kB 0*512kB 0*1024kB 1*2048kB 0*4096kB = 2440kB Nov 9 19:07:16 vs302 kernel: Node 0 DMA32: 129*4kB 67*8kB 30*16kB 19*32kB 6*64kB 2*128kB 1*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 3036kB Nov 9 19:07:16 vs302 kernel: 182 total pagecache pages Nov 9 19:07:16 vs302 kernel: 0 pages in swap cache Nov 9 19:07:16 vs302 kernel: Swap cache stats: add 0, delete 0, find 0/0 Nov 9 19:07:16 vs302 kernel: Free swap = 0kB Nov 9 19:07:16 vs302 kernel: Total swap = 0kB Nov 9 19:07:16 vs302 kernel: 157439 pages RAM Nov 9 19:07:16 vs302 kernel: 6271 pages reserved Nov 9 19:07:16 vs302 kernel: 2686 pages shared Nov 9 19:07:16 vs302 kernel: 146395 pages non-shared Nov 9 19:07:16 vs302 kernel: [ pid ] uid tgid total_vm rss cpu oom_adj oom_score_adj name Nov 9 19:07:16 vs302 kernel: [ 271] 0 271 2798 231 0 -17 -1000 udevd Nov 9 19:07:16 vs302 kernel: [ 476] 0 476 2797 230 0 -17 -1000 udevd Nov 9 19:07:16 vs302 kernel: [ 718] 0 718 2279 122 0 0 0 dhclient Nov 9 19:07:16 vs302 kernel: [ 762] 0 762 6909 58 0 -17 -1000 auditd Nov 9 19:07:16 vs302 kernel: [ 787] 0 787 62270 147 0 0 0 rsyslogd Nov 9 19:07:16 vs302 kernel: [ 801] 25 801 40326 2655 0 0 0 named Nov 9 19:07:16 vs302 kernel: [ 850] 0 850 16563 172 0 -17 -1000 sshd Nov 9 19:07:16 vs302 kernel: [ 875] 0 875 23451 240 0 0 0 sshd Nov 9 19:07:16 vs302 kernel: [ 966] 498 966 4780 44 0 0 0 wrapper Nov 9 19:07:16 vs302 kernel: [ 968] 498 968 497404 40812 0 0 0 java Nov 9 19:07:16 vs302 kernel: [ 1057] 0 1057 20216 225 0 0 0 master Nov 9 19:07:16 vs302 kernel: [ 1064] 89 1064 20278 209 0 0 0 qmgr Nov 9 19:07:16 vs302 kernel: [ 1071] 0 1071 27075 121 0 0 0 bash Nov 9 19:07:16 vs302 kernel: [ 1111] 0 1111 24880 350 0 0 0 httpd Nov 9 19:07:16 vs302 kernel: [ 1117] 48 1117 24913 351 0 0 0 httpd Nov 9 19:07:16 vs302 kernel: [ 1118] 48 1118 24880 337 0 0 0 httpd Nov 9 19:07:16 vs302 kernel: [ 1119] 48 1119 24880 337 0 0 0 httpd Nov 9 19:07:16 vs302 kernel: [ 1120] 48 1120 24880 337 0 0 0 httpd Nov 9 19:07:16 vs302 kernel: [ 1121] 48 1121 24880 337 0 0 0 httpd Nov 9 19:07:16 vs302 kernel: [ 1122] 48 1122 24880 337 0 0 0 httpd Nov 9 19:07:16 vs302 kernel: [ 1124] 48 1124 24880 337 0 0 0 httpd Nov 9 19:07:16 vs302 kernel: [ 1125] 48 1125 24880 337 0 0 0 httpd Nov 9 19:07:16 vs302 kernel: [ 1129] 0 1129 29313 151 0 0 0 crond Nov 9 19:07:16 vs302 kernel: [ 1143] 0 1143 1018 22 0 0 0 agetty Nov 9 19:07:16 vs302 kernel: [ 1146] 0 1146 1015 22 0 0 0 mingetty Nov 9 19:07:16 vs302 kernel: [ 1514] 0 1514 23451 237 0 0 0 sshd Nov 9 19:07:16 vs302 kernel: [ 1517] 0 1517 27075 113 0 0 0 bash Nov 9 19:07:16 vs302 kernel: [ 1641] 89 1641 20236 218 0 0 0 pickup Nov 9 19:07:16 vs302 kernel: [ 1659] 0 1659 25234 39 0 0 0 tail Nov 9 19:07:16 vs302 kernel: [ 1660] 0 1660 89903 85712 0 0 0 setsebool Nov 9 19:07:16 vs302 kernel: Out of memory: Kill process 1660 (setsebool) score 568 or sacrifice child Nov 9 19:07:16 vs302 kernel: Killed process 1660, UID 0, (setsebool) total-vm:359612kB, anon-rss:342708kB, file-rss:140kB

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• Server randomly freezes

  - by PsySkeletor

  Im facing a very strange issue, my debian squeeze freezes up always at night (Berlin, time). Here is what i get from a time and after doing this a few times, it becomes frozen and must be hard-reset. From /var/log/messages Dec 11 01:36:11 srv156 kernel: [125983.204251] CPU 1: Dec 11 01:36:11 srv156 kernel: [125983.204251] Modules linked in: xt_multiport nf_conntrack_ipv4 nf_defrag_ipv4 xt_recent xt_state nf_conntrack xt_tcpudp iptable_filter ip_tables x_tables hwmon_vid snd_hda_codec_atihdmi snd_hda_intel snd_hda_codec snd_hwdep snd_pcm radeon snd_timer ttm drm_kms_helper snd k10temp i2c_piix4 soundcore snd_page_alloc edac_core parport_pc drm i2c_algo_bit i2c_core shpchp pci_hotplug pcspkr edac_mce_amd parport wmi evdev processor button ext3 jbd mbcache raid1 md_mod sd_mod crc_t10dif ata_generic ahci ohci_hcd pata_atiixp e100 mii libata xhci floppy ehci_hcd thermal thermal_sys usbcore scsi_mod nls_base [last unloaded: i2c_dev] Dec 11 01:36:11 srv156 kernel: [125983.204251] Pid: 758, comm: flush-9:0 Tainted: G B 2.6.32-5-amd64 #1 GA-78LMT-USB3 Dec 11 01:36:11 srv156 kernel: [125983.204251] RIP: 0010:[<ffffffff810b3506>] [<ffffffff810b3506>] find_get_pages_tag+0x66/0xdd Dec 11 01:36:11 srv156 kernel: [125983.204251] RSP: 0018:ffff8804235e7b30 EFLAGS: 00000286 Dec 11 01:36:11 srv156 kernel: [125983.204251] RAX: ffffffffffffffff RBX: ffff8804235e7c00 RCX: 0000000000000000 Dec 11 01:36:11 srv156 kernel: [125983.204251] RDX: 0000000000040000 RSI: ffffea000496b2a8 RDI: ffffea000496b2a0 Dec 11 01:36:11 srv156 kernel: [125983.204251] RBP: ffffffff8101166e R08: ffff8804235e7af0 R09: 0000000000000000 Dec 11 01:36:11 srv156 kernel: [125983.204251] R10: 0000000000000000 R11: 0000000000040000 R12: ffff8804235e7c08 Dec 11 01:36:11 srv156 kernel: [125983.204251] R13: 0000000d22678a20 R14: ffff8804235e7af0 R15: 00000000091b9060 Dec 11 01:36:11 srv156 kernel: [125983.204251] FS: 0000000000000000(0000) GS:ffff880010440000(0000) knlGS:000000007ebf7b70 Dec 11 01:36:11 srv156 kernel: [125983.204522] CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b Dec 11 01:36:11 srv156 kernel: [125983.204522] CR2: 00000000dec86000 CR3: 0000000001001000 CR4: 00000000000006e0 Dec 11 01:36:11 srv156 kernel: [125983.204522] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 Dec 11 01:36:11 srv156 kernel: [125983.204522] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Dec 11 01:36:11 srv156 kernel: [125983.204522] Call Trace: Dec 11 01:36:11 srv156 kernel: [125983.204522] [<ffffffff810bb792>] ? pagevec_lookup_tag+0x1a/0x21 Dec 11 01:36:11 srv156 kernel: [125983.204522] [<ffffffff810ba330>] ? write_cache_pages+0x162/0x327 Dec 11 01:36:11 srv156 kernel: [125983.204522] [<ffffffff810b9d48>] ? __writepage+0x0/0x25 Dec 11 01:36:11 srv156 kernel: [125983.204522] [<ffffffff8110758a>] ? writeback_single_inode+0xe7/0x2da Dec 11 01:36:11 srv156 kernel: [125983.204522] [<ffffffff81108290>] ? writeback_inodes_wb+0x424/0x4ff Dec 11 01:36:11 srv156 kernel: [125983.204522] [<ffffffff81108497>] ? wb_writeback+0x12c/0x1ab Dec 11 01:36:11 srv156 kernel: [125983.204522] [<ffffffff8110870d>] ? wb_do_writeback+0x14f/0x165 Dec 11 01:36:11 srv156 kernel: [125983.204522] [<ffffffff81108754>] ? bdi_writeback_task+0x31/0xaa Dec 11 01:36:11 srv156 kernel: [125983.204522] [<ffffffff810c8664>] ? bdi_start_fn+0x0/0xd0 Dec 11 01:36:11 srv156 kernel: [125983.204522] [<ffffffff810c86d4>] ? bdi_start_fn+0x70/0xd0 Dec 11 01:36:11 srv156 kernel: [125983.204522] [<ffffffff810c8664>] ? bdi_start_fn+0x0/0xd0 Dec 11 01:36:11 srv156 kernel: [125983.204522] [<ffffffff81064ac1>] ? kthread+0x79/0x81 Dec 11 01:36:11 srv156 kernel: [125983.204522] [<ffffffff81011baa>] ? child_rip+0xa/0x20 Dec 11 01:36:11 srv156 kernel: [125983.204522] [<ffffffff81064a48>] ? kthread+0x0/0x81 Dec 11 01:36:11 srv156 kernel: [125983.204522] [<ffffffff81011ba0>] ? child_rip+0x0/0x20 From /var/log/syslog Dec 10 21:20:29 srv156 kernel: [110625.162930] BUG: Bad page map in process java pte:14fa4f067 pmd:424b54067 Dec 10 21:20:29 srv156 kernel: [110625.162937] page:ffffea000496c148 flags:0200000000000878 count:2 mapcount:-1 mapping:ffff88014f8d7de8 index:2f4 Dec 10 21:20:29 srv156 kernel: [110625.162946] addr:0000000009096000 vm_flags:00100077 anon_vma:ffff880422410d40 mapping:(null) index:9096 Dec 10 21:20:29 srv156 kernel: [110625.162955] Pid: 21356, comm: java Tainted: G B 2.6.32-5-amd64 #1 Dec 10 21:20:29 srv156 kernel: [110625.162961] Call Trace: Dec 10 21:20:29 srv156 kernel: [110625.162966] [<ffffffff810ca4bf>] ? print_bad_pte+0x232/0x24a Dec 10 21:20:29 srv156 kernel: [110625.162973] [<ffffffff810cb56f>] ? unmap_vmas+0x62d/0x931 Dec 10 21:20:29 srv156 kernel: [110625.162980] [<ffffffff810cfc74>] ? exit_mmap+0xc4/0x148 Dec 10 21:20:29 srv156 kernel: [110625.162986] [<ffffffff8104bbc1>] ? mmput+0x3c/0xdf Dec 10 21:20:29 srv156 kernel: [110625.162992] [<ffffffff8104f81e>] ? exit_mm+0x102/0x10d Dec 10 21:20:29 srv156 kernel: [110625.162998] [<ffffffff81051243>] ? do_exit+0x1f8/0x6c9 Dec 10 21:20:29 srv156 kernel: [110625.163004] [<ffffffff81071abb>] ? futex_wake+0xd6/0xe7 Dec 10 21:20:29 srv156 kernel: [110625.163010] [<ffffffff8105178a>] ? do_group_exit+0x76/0x9d Dec 10 21:20:29 srv156 kernel: [110625.163016] [<ffffffff8105df9f>] ? get_signal_to_deliver+0x310/0x339 Dec 10 21:20:29 srv156 kernel: [110625.163023] [<ffffffff81010037>] ? do_notify_resume+0x87/0x73f Dec 10 21:20:29 srv156 kernel: [110625.163029] [<ffffffff810cc664>] ? handle_mm_fault+0x7aa/0x80f Dec 10 21:20:29 srv156 kernel: [110625.163036] [<ffffffff81073f14>] ? compat_sys_futex+0x10d/0x12b Dec 10 21:20:29 srv156 kernel: [110625.163043] [<ffffffff812fb546>] ? do_page_fault+0x2e0/0x2fc Dec 10 21:20:29 srv156 kernel: [110625.163049] [<ffffffff81010e0e>] ? int_signal+0x12/0x17 Dec 10 21:20:29 srv156 kernel: [110625.163114] BUG: Bad page state in process java pfn:14fa0c Dec 10 21:20:29 srv156 kernel: [110625.163120] page:ffffea000496b2a0 flags:020000000002001c count:0 mapcount:-1 mapping:ffff88039dc0db30 index:11e3 Dec 10 21:20:29 srv156 kernel: [110625.164563] Pid: 21356, comm: java Tainted: G B 2.6.32-5-amd64 #1 Dec 10 21:20:29 srv156 kernel: [110625.164570] Call Trace: Dec 10 21:20:29 srv156 kernel: [110625.164578] [<ffffffff810b71a9>] ? bad_page+0x116/0x129 Dec 10 21:20:29 srv156 kernel: [110625.164586] [<ffffffff810b7692>] ? free_pages_check+0x38/0x57 Dec 10 21:20:29 srv156 kernel: [110625.164595] [<ffffffff810b89cf>] ? free_hot_cold_page+0x46/0x190 Dec 10 21:20:29 srv156 kernel: [110625.164603] [<ffffffff810b8b82>] ? __pagevec_free+0x69/0x7f Dec 10 21:20:29 srv156 kernel: [110625.164611] [<ffffffff810bba3f>] ? release_pages+0x137/0x18d Dec 10 21:20:29 srv156 kernel: [110625.164620] [<ffffffff810d8559>] ? free_pages_and_swap_cache+0x57/0x73 Dec 10 21:20:29 srv156 kernel: [110625.164629] [<ffffffff810cb5ed>] ? unmap_vmas+0x6ab/0x931 Dec 10 21:20:29 srv156 kernel: [110625.164637] [<ffffffff810cfc74>] ? exit_mmap+0xc4/0x148 Dec 10 21:20:29 srv156 kernel: [110625.164644] [<ffffffff8104bbc1>] ? mmput+0x3c/0xdf Dec 10 21:20:29 srv156 kernel: [110625.164652] [<ffffffff8104f81e>] ? exit_mm+0x102/0x10d Dec 10 21:20:29 srv156 kernel: [110625.164660] [<ffffffff81051243>] ? do_exit+0x1f8/0x6c9 Dec 10 21:20:29 srv156 kernel: [110625.164667] [<ffffffff81071abb>] ? futex_wake+0xd6/0xe7 Dec 10 21:20:29 srv156 kernel: [110625.164675] [<ffffffff8105178a>] ? do_group_exit+0x76/0x9d Dec 10 21:20:29 srv156 kernel: [110625.164683] [<ffffffff8105df9f>] ? get_signal_to_deliver+0x310/0x339 Dec 10 21:20:29 srv156 kernel: [110625.164692] [<ffffffff81010037>] ? do_notify_resume+0x87/0x73f Dec 10 21:20:29 srv156 kernel: [110625.164700] [<ffffffff810cc664>] ? handle_mm_fault+0x7aa/0x80f The last piece of log, has been recently posted, because I've just found it. It seems Java process do something and began to slowly eat all the resources of the server. I don't know exactly if this could be the root cause. Im using Debian Squeeze. uname -a Linux srv156 2.6.32-5-amd64 #1 SMP Sun Sep 23 11:00:33 UTC 2012 x86_64 GNU/Linux I really will appreciate your help, i dont know what more to do.

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• Nginx 500 Internal Server error on subdirectory

  - by juyoung518

  I'm getting a 500 Internal Server error only on sub directories. For example, If my website is example.com, example.com/index.php works. But example.com/phpbb/index.php doesn't work. It just turns up a blank php page. The HTTP header shows HTTP error 500 Internal Server error. If I enter example.com/phpbb/index.php/somedirectory, the index.php of my root directory shows up. This is all very strange. I have tried searching etc but nothing worked. tried re-installing nginx but not fixed. I'm sure I got the DNS configured right. My Nginx Config /sites-available/example.com server { server_name www.example.com; return 301 https://example.com$request_uri; } server { listen 443; listen 80; #listen 80; ## listen for ipv4; this line is default and implied #listen [::]:80 default_server ipv6only=on; ## listen for ipv6 root /var/www/example.com/public_html; index index.html index.php index.htm; ssl on; ssl_certificate /etc/nginx/ssl/cert.pem; ssl_certificate_key /etc/nginx/ssl/ssl.key; ssl_session_timeout 5m; ssl_protocols TLSv1 TLSv1.1 TLSv1.2; ssl_ciphers ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:ECDH+3DES:DH+3DES:RSA+AESGCM:RSA+AES:RSA+3DES:!aNULL:!MD5:!DSS; ssl_prefer_server_ciphers on; ssl_stapling on; resolver 8.8.8.8; add_header Strict-Transport-Security max-age=63072000; # Make site accessible from http://localhost/ server_name example.com; location ~* \.(jpg|jpeg|png|gif|ico|css|js|bmp)$ { expires 365d; add_header Cache-Control public; } if ($scheme = http) { return 301 https://example.com$request_uri; } location / { # First attempt to serve request as file, then # as directory, then fall back to displaying a 404. try_files $uri $uri/ /index.php; # Uncomment to enable naxsi on this location # include /etc/nginx/naxsi.rules } if ($http_user_agent ~ (musobot|screenshot|AhrefsBot|picsearch|Gender|HostTracker|Java/1.7.0_51|Java) ) { return 403; } location /phpmyadmin { root /usr/share/; index index.php index.html index.htm; location ~ ^/phpmyadmin/(.+\.php)$ { try_files $uri =404; root /usr/share/; fastcgi_pass 127.0.0.1:9000; fastcgi_index index.php; fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; include /etc/nginx/fastcgi_params; } location ~* ^/phpmyadmin/(.+\.(jpg|jpeg|gif|css|png|js|ico|html|xml|txt))$ { root /usr/share/; } } location /phpMyAdmin { rewrite ^/* /phpmyadmin last; } location /doc/ { alias /usr/share/doc/; autoindex on; allow 127.0.0.1; allow ::1; deny all; } # Only for nginx-naxsi used with nginx-naxsi-ui : process denied requests #location /RequestDenied { # proxy_pass http://127.0.0.1:8080; #} #error_page 404 /404.html; # redirect server error pages to the static page /50x.html # error_page 500 502 503 504 /50x.html; location = /50x.html { root /usr/share/nginx/www; } # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000 # location ~ \.php$ { try_files $uri =404; fastcgi_split_path_info ^(.+\.php)(/.+)$; # NOTE: You should have "cgi.fix_pathinfo = 0;" in php.ini # With php5-cgi alone: fastcgi_pass 127.0.0.1:9000; # With php5-fpm: #fastcgi_pass unix:/var/run/php5-fpm.sock; fastcgi_index index.php; include /etc/nginx/fastcgi_params; fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; fastcgi_buffer_size 128k; fastcgi_buffers 256 16k; fastcgi_busy_buffers_size 256k; fastcgi_temp_file_write_size 256k; fastcgi_read_timeout 240; # deny access to .htaccess files, if Apache's document root # concurs with nginx's one # location ~ /\.ht { deny all; } } } nginx.conf user www-data; worker_processes 1; pid /var/run/nginx.pid; events { worker_connections 768; # multi_accept on; } http { ## Block spammers and other unwanted visitors ## include /etc/nginx/blockips.conf; fastcgi_cache_path /var/cache/nginx levels=1:2 keys_zone=microcache:10m max_size=1000m inactive=60m; ## # Basic Settings ## sendfile on; tcp_nopush on; tcp_nodelay on; keepalive_timeout 100; types_hash_max_size 2048; server_tokens off; # server_names_hash_bucket_size 64; # server_name_in_redirect off; include /etc/nginx/mime.types; default_type application/octet-stream; ## # Logging Settings ## access_log off; error_log /var/log/nginx/error.log; ssl_session_cache shared:SSL:10m; ssl_session_timeout 10m; ssl_ciphers ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:ECDH+3DES:DH+3DES:RSA+AESGCM:RSA+AES:RSA+3DES:!aNULL:!MD5:!DSS; ssl_prefer_server_ciphers on; ## # File Cache Settings ## open_file_cache max=5000 inactive=5m; open_file_cache_valid 2m; open_file_cache_min_uses 1; open_file_cache_errors on; ## # Gzip Settings ## gzip on; gzip_disable "msie6"; gzip_vary on; gzip_proxied any; gzip_comp_level 6; gzip_buffers 16 8k; gzip_http_version 1.1; gzip_types text/plain text/x-js text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript; ## # nginx-naxsi config ## # Uncomment it if you installed nginx-naxsi ## #include /etc/nginx/naxsi_core.rules; ## # nginx-passenger config ## # Uncomment it if you installed nginx-passenger ## #passenger_root /usr; #passenger_ruby /usr/bin/ruby; ## # Virtual Host Configs ## include /etc/nginx/conf.d/*.conf; include /etc/nginx/sites-enabled/*;

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• mdadm: Win7-install created a boot partition on one of my RAID6 drives. How to rebuild?

  - by EXIT_FAILURE

  My problem happened when I attempted to install Windows 7 on it's own SSD. The Linux OS I used which has knowledge of the software RAID system is on a SSD that I disconnected prior to the install. This was so that windows (or I) wouldn't inadvertently mess it up. However, and in retrospect, foolishly, I left the RAID disks connected, thinking that windows wouldn't be so ridiculous as to mess with a HDD that it sees as just unallocated space. Boy was I wrong! After copying over the installation files to the SSD (as expected and desired), it also created an ntfs partition on one of the RAID disks. Both unexpected and totally undesired! . I changed out the SSDs again, and booted up in linux. mdadm didn't seem to have any problem assembling the array as before, but if I tried to mount the array, I got the error message: mount: wrong fs type, bad option, bad superblock on /dev/md0, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so dmesg: EXT4-fs (md0): ext4_check_descriptors: Block bitmap for group 0 not in group (block 1318081259)! EXT4-fs (md0): group descriptors corrupted! I then used qparted to delete the newly created ntfs partition on /dev/sdd so that it matched the other three /dev/sd{b,c,e}, and requested a resync of my array with echo repair > /sys/block/md0/md/sync_action This took around 4 hours, and upon completion, dmesg reports: md: md0: requested-resync done. A bit brief after a 4-hour task, though I'm unsure as to where other log files exist (I also seem to have messed up my sendmail configuration). In any case: No change reported according to mdadm, everything checks out. mdadm -D /dev/md0 still reports: Version : 1.2 Creation Time : Wed May 23 22:18:45 2012 Raid Level : raid6 Array Size : 3907026848 (3726.03 GiB 4000.80 GB) Used Dev Size : 1953513424 (1863.02 GiB 2000.40 GB) Raid Devices : 4 Total Devices : 4 Persistence : Superblock is persistent Update Time : Mon May 26 12:41:58 2014 State : clean Active Devices : 4 Working Devices : 4 Failed Devices : 0 Spare Devices : 0 Layout : left-symmetric Chunk Size : 4K Name : okamilinkun:0 UUID : 0c97ebf3:098864d8:126f44e3:e4337102 Events : 423 Number Major Minor RaidDevice State 0 8 16 0 active sync /dev/sdb 1 8 32 1 active sync /dev/sdc 2 8 48 2 active sync /dev/sdd 3 8 64 3 active sync /dev/sde Trying to mount it still reports: mount: wrong fs type, bad option, bad superblock on /dev/md0, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so and dmesg: EXT4-fs (md0): ext4_check_descriptors: Block bitmap for group 0 not in group (block 1318081259)! EXT4-fs (md0): group descriptors corrupted! I'm a bit unsure where to proceed from here, and trying stuff "to see if it works" is a bit too risky for me. This is what I suggest I should attempt to do: Tell mdadm that /dev/sdd (the one that windows wrote into) isn't reliable anymore, pretend it is newly re-introduced to the array, and reconstruct its content based on the other three drives. I also could be totally wrong in my assumptions, that the creation of the ntfs partition on /dev/sdd and subsequent deletion has changed something that cannot be fixed this way. My question: Help, what should I do? If I should do what I suggested , how do I do that? From reading documentation, etc, I would think maybe: mdadm --manage /dev/md0 --set-faulty /dev/sdd mdadm --manage /dev/md0 --remove /dev/sdd mdadm --manage /dev/md0 --re-add /dev/sdd However, the documentation examples suggest /dev/sdd1, which seems strange to me, as there is no partition there as far as linux is concerned, just unallocated space. Maybe these commands won't work without. Maybe it makes sense to mirror the partition table of one of the other raid devices that weren't touched, before --re-add. Something like: sfdisk -d /dev/sdb | sfdisk /dev/sdd Bonus question: Why would the Windows 7 installation do something so st...potentially dangerous? Update I went ahead and marked /dev/sdd as faulty, and removed it (not physically) from the array: # mdadm --manage /dev/md0 --set-faulty /dev/sdd # mdadm --manage /dev/md0 --remove /dev/sdd However, attempting to --re-add was disallowed: # mdadm --manage /dev/md0 --re-add /dev/sdd mdadm: --re-add for /dev/sdd to /dev/md0 is not possible --add, was fine. # mdadm --manage /dev/md0 --add /dev/sdd mdadm -D /dev/md0 now reports the state as clean, degraded, recovering, and /dev/sdd as spare rebuilding. /proc/mdstat shows the recovery progress: md0 : active raid6 sdd[4] sdc[1] sde[3] sdb[0] 3907026848 blocks super 1.2 level 6, 4k chunk, algorithm 2 [4/3] [UU_U] [>....................] recovery = 2.1% (42887780/1953513424) finish=348.7min speed=91297K/sec nmon also shows expected output: ¦sdb 0% 87.3 0.0| > |¦ ¦sdc 71% 109.1 0.0|RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR > |¦ ¦sdd 40% 0.0 87.3|WWWWWWWWWWWWWWWWWWWW > |¦ ¦sde 0% 87.3 0.0|> || It looks good so far. Crossing my fingers for another five+ hours :) Update 2 The recovery of /dev/sdd finished, with dmesg output: [44972.599552] md: md0: recovery done. [44972.682811] RAID conf printout: [44972.682815] --- level:6 rd:4 wd:4 [44972.682817] disk 0, o:1, dev:sdb [44972.682819] disk 1, o:1, dev:sdc [44972.682820] disk 2, o:1, dev:sdd [44972.682821] disk 3, o:1, dev:sde Attempting mount /dev/md0 reports: mount: wrong fs type, bad option, bad superblock on /dev/md0, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so And on dmesg: [44984.159908] EXT4-fs (md0): ext4_check_descriptors: Block bitmap for group 0 not in group (block 1318081259)! [44984.159912] EXT4-fs (md0): group descriptors corrupted! I'm not sure what do do now. Suggestions? Output of dumpe2fs /dev/md0: dumpe2fs 1.42.8 (20-Jun-2013) Filesystem volume name: Atlas Last mounted on: /mnt/atlas Filesystem UUID: e7bfb6a4-c907-4aa0-9b55-9528817bfd70 Filesystem magic number: 0xEF53 Filesystem revision #: 1 (dynamic) Filesystem features: has_journal ext_attr resize_inode dir_index filetype extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize Filesystem flags: signed_directory_hash Default mount options: user_xattr acl Filesystem state: clean Errors behavior: Continue Filesystem OS type: Linux Inode count: 244195328 Block count: 976756712 Reserved block count: 48837835 Free blocks: 92000180 Free inodes: 243414877 First block: 0 Block size: 4096 Fragment size: 4096 Reserved GDT blocks: 791 Blocks per group: 32768 Fragments per group: 32768 Inodes per group: 8192 Inode blocks per group: 512 RAID stripe width: 2 Flex block group size: 16 Filesystem created: Thu May 24 07:22:41 2012 Last mount time: Sun May 25 23:44:38 2014 Last write time: Sun May 25 23:46:42 2014 Mount count: 341 Maximum mount count: -1 Last checked: Thu May 24 07:22:41 2012 Check interval: 0 (<none>) Lifetime writes: 4357 GB Reserved blocks uid: 0 (user root) Reserved blocks gid: 0 (group root) First inode: 11 Inode size: 256 Required extra isize: 28 Desired extra isize: 28 Journal inode: 8 Default directory hash: half_md4 Directory Hash Seed: e177a374-0b90-4eaa-b78f-d734aae13051 Journal backup: inode blocks dumpe2fs: Corrupt extent header while reading journal super block

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• Network throughput issue (ARP-related)

  - by Joel Coel

  The small college where I work is having some very strange network issues. I'm looking for any advice or ideas here. We were fine over the summer, but the trouble began few days after students returned to campus in force for the fall term. Symptoms The main symptom is that internet access will work, but it's very slow... often to the point of timeouts. As an example, a typical result from Speedtest.net will return .4Mbps download, but allow 3 to 8 Mbps upload speed. Lesser symptoms may include severely limited performance transferring data to and from our file server, or even in some cases the inability to log in to the computer (cannot reach the domain controller). The issue crosses multiple vlans, and has effected devices on nearly every vlan we operate. The issue does not impact all machines on the network. An unaffected machine will typically see at least 11Mbps download from speedtest.net, and perhaps much more depending on larger campus traffic patterns at the time. There is one variation on the larger issue. We have one vlan where users were unable to log into nearly all of the machines at all. IT staff would log in using a local administrator account (or in some cases cached credentials), and from there a release/renew or pinging the gateway would allow the machine to work... for a while. Complicating this issue is that this vlan covers our computer labs, which use software called Deep Freeze to completely reset the hard drives after a reboot. It could just the same issue manifesting differently because of stale data on machines that have not permanently altered low-level info for weeks. We were able to solve this, however, by creating a new vlan and moving the labs over to the new vlan wholesale. Instigations Eventually we noticed that the effected machines all had recent dhcp leases. We can predict when a machine will become "slow" by watching when a dhcp lease comes up for renewal. We played with setting the lease time very short for a test vlan, but all that did was remove our ability to predict when the machine would become slow. Machines with static IPs have pretty much always worked normally. Manually releasing/renewing an address will never cause a machine to become slow. In fact, in some cases this process has fixed a machine in that state. Most of the time, though, it doesn't help. We also noticed that mobile machines like laptops are likely to become slow when they cross to new vlans. Wireless on campus is divided up into "zones", where each zone maps to a small set of buildings. Moving to a new building can place you in a zone, thereby causing you to get a new address. A machine resuming from sleep mode is also very likely to be slow. Mitigations Sometimes, but not always, clearing the arp cache on an effected machine will allow it to work normally again. As already mentioned, releasing/renewing a local machine's IP address can fix that machine, but it's not guaranteed. Pinging the default gateway can also sometimes help with a slow machine. What seems to help most to mitigate the issue is clearing the arp cache on our core layer-3 switch. This switch is used for our dhcp system as the default gateway on all vlans, and it handles inter-vlan routing. The model is a 3Com 4900SX. To try to mitigate the issue, we have the cache timeout set on the switch all the way down to the lowest possible time, but it hasn't helped. I also put together a script that runs every few minutes to automatically connect to the switch and reset the cache. Unfortunately, this does not always work, and can even cause some machines to end up in the slow state for a short time (though these seem to correct themselves after a few minutes). We currently have a scheduled job that runs every 10 minutes to force the core switch to clear it's ARP cache, but this is far from perfect or desirable. Reproduction We now have a test machine that we can force into the slow state at will. It is connected to a switch with ports set up for each of our vlans. We make the machine slow by connecting to different vlans, and after a new connection or two it will be slow. It's also worth noting in this section that this has happened before at the start of prior terms, but in the past the problem has gone away on it's own after a few days. It solved itself before we had a chance to do much diagnostic work... hence why we've allowed it to drag so long into the term this time 'round; the expectation was this would be a short-lived situation. Other Factors It's worth mentioning that we have had about half a dozen switches just outright fail over the last year. These are mainly 2003/2004-era 3Coms (mostly 4200's) that were all put in at about the same time. They should still be covered under warranty, buy HP has made getting service somewhat difficult. Mostly in power supplies that have failed, but in a couple cases we have used a power supply from a switch with a failed mainboard to bring a switch with a failed power supply back to life. We do have UPS devices on all but three of four switches now, but that was not the case when I started two and a half years ago. Severe budget constraints (we were on the Dept. of Ed's financially challenged institutions list a couple years back) have forced me to look to the likes of Netgear and TrendNet for replacements, but so far these low-end models seem to be holding their own. It's also worth mentioning that the big change on our network this summer was migrating from a single cross-campus wireless SSID to the zoned approach mentioned earlier. I don't think this is the source of the issue, as like I've said: we've seen this before. However, it's possible this is exacerbating the issue, and may be much of the reason it's been so hard to isolate. Diagnosis At first it seemed clear to us, given the timing and persistent nature of the problem, that the source of the issue was an infected (or malicious) student machine doing ARP cache poisoning. However, repeated attempts to isolate the source have failed. Those attempts include numerous wireshark packet traces, and even taking entire buildings offline for brief periods. We have not been able even to find a smoking gun bad ARP entry. My current best guess is an overloaded or failing core switch, but I'm not sure on how to test for this, and the cost of replacing it blindly is steep. Again, any ideas appreciated.

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• How to improve Varnish performance?

  - by Darkseal

  We're experiencing a strange problem with our current Varnish configuration. 4x Web Servers (IIS 6.5 on Windows 2003 Server, each installed on a Intel(R) Xeon(R) CPU E5450 @ 3.00GHz Quad Core, 4GB RAM) 3x Varnish Servers (varnish-3.0.3 revision 9e6a70f on Ubuntu 12.04.2 LTS - 64 bit/precise, Kernel Linux 3.2.0-29-generic, each installed on a Intel(R) Xeon(R) CPU E5450 @ 3.00GHz Quad Core, 4GB RAM) The Varnish Servers performance are awfully bad in general, to the point that if we shut down one of them the other two are unable to fullfill all the requests and start to skip beats resulting in pending requests, timeouts, 404, etc. What can we do to improve our Varnish performance? Considering that we're getting less than 5k request per seconds during our max peak, we should be able to serve our pages even with a single one of them without any problem. We use a standard, vanilla CFG, as shown by this varnishadm param.show output: acceptor_sleep_decay 0.900000 [] acceptor_sleep_incr 0.001000 [s] acceptor_sleep_max 0.050000 [s] auto_restart on [bool] ban_dups on [bool] ban_lurker_sleep 0.010000 [s] between_bytes_timeout 60.000000 [s] cc_command "exec gcc -std=gnu99 -g -O2 -pthread -fpic -shared - Wl,-x -o %o %s" cli_buffer 8192 [bytes] cli_timeout 20 [seconds] clock_skew 10 [s] connect_timeout 0.700000 [s] critbit_cooloff 180.000000 [s] default_grace 10.000000 [seconds] default_keep 0.000000 [seconds] default_ttl 120.000000 [seconds] diag_bitmap 0x0 [bitmap] esi_syntax 0 [bitmap] expiry_sleep 1.000000 [seconds] fetch_chunksize 128 [kilobytes] fetch_maxchunksize 262144 [kilobytes] first_byte_timeout 60.000000 [s] group varnish (113) gzip_level 6 [] gzip_memlevel 8 [] gzip_stack_buffer 32768 [Bytes] gzip_tmp_space 0 [] gzip_window 15 [] http_gzip_support off [bool] http_max_hdr 64 [header lines] http_range_support on [bool] http_req_hdr_len 8192 [bytes] http_req_size 32768 [bytes] http_resp_hdr_len 8192 [bytes] http_resp_size 32768 [bytes] idle_send_timeout 60 [seconds] listen_address :80 listen_depth 1024 [connections] log_hashstring on [bool] log_local_address off [bool] lru_interval 2 [seconds] max_esi_depth 5 [levels] max_restarts 4 [restarts] nuke_limit 50 [allocations] pcre_match_limit 10000 [] pcre_match_limit_recursion 10000 [] ping_interval 3 [seconds] pipe_timeout 60 [seconds] prefer_ipv6 off [bool] queue_max 100 [%] rush_exponent 3 [requests per request] saintmode_threshold 10 [objects] send_timeout 600 [seconds] sess_timeout 5 [seconds] sess_workspace 16384 [bytes] session_linger 50 [ms] session_max 100000 [sessions] shm_reclen 255 [bytes] shm_workspace 8192 [bytes] shortlived 10.000000 [s] syslog_cli_traffic on [bool] thread_pool_add_delay 2 [milliseconds] thread_pool_add_threshold 2 [requests] thread_pool_fail_delay 200 [milliseconds] thread_pool_max 2000 [threads] thread_pool_min 5 [threads] thread_pool_purge_delay 1000 [milliseconds] thread_pool_stack unlimited [bytes] thread_pool_timeout 300 [seconds] thread_pool_workspace 65536 [bytes] thread_pools 2 [pools] thread_stats_rate 10 [requests] user varnish (106) vcc_err_unref on [bool] vcl_dir /etc/varnish vcl_trace off [bool] vmod_dir /usr/lib/varnish/vmods waiter default (epoll, poll) This is our default.vcl file: LINK sub vcl_recv { # BASIC recv COMMANDS: # # lookup -> search the item in the cache # pass -> always serve a fresh item (no-caching) # pipe -> like pass but ensures a direct-connection with the backend (no-cache AND no-proxy) # Allow the backend to serve up stale content if it is responding slow. # This defines when Varnish should use a stale object if it has one in the cache. set req.grace = 30s; if (client.ip == "127.0.0.1") { # request from NGINX - do not alter X-Forwarded-For set req.http.HTTPS = "on"; } else { # Add an X-Forwarded-For to keep track of original request unset req.http.HTTPS; unset req.http.X-Forwarded-For; set req.http.X-Forwarded-For = client.ip; } set req.backend = www_director; # Strip all cookies to force an anonymous request when the back-end servers are down. if (!req.backend.healthy) { unset req.http.Cookie; } ## HHTP Accept-Encoding if (req.http.Accept-Encoding) { if (req.http.Accept-Encoding ~ "gzip") { set req.http.Accept-Encoding = "gzip"; } else if (req.http.Accept-Encoding ~ "deflate") { set req.http.Accept-Encoding = "deflate"; } else { unset req.http.Accept-Encoding; } } if (req.request != "GET" && req.request != "HEAD" && req.request != "PUT" && req.request != "POST" && req.request != "TRACE" && req.request != "OPTIONS" && req.request != "DELETE") { /* non-RFC2616 or CONNECT */ return (pipe); } if (req.request != "GET" && req.request != "HEAD") { /* only deal with GET and HEAD by default */ return (pass); } if (req.http.Authorization) { return (pass); } if (req.http.HTTPS ~ "on") { return (pass); } ###################################################### # COOKIE HANDLING ###################################################### # METHOD 1: do not remove cookies, but pass the page if they contain TB_NC if (!(req.url ~ "(?i)\.(png|gif|ipeg|jpg|ico|swf|css|js)(\?[a-z0-9]+)?$")) { if (req.http.Cookie && req.http.Cookie ~ "TB_NC") { return (pass); } } return (lookup); } # Code determining what to do when serving items from the IIS Server sub vcl_fetch { unset beresp.http.Server; set beresp.http.Server = "Server-1"; # Allow items to be stale if needed. This is the maximum time Varnish should keep an object. set beresp.grace = 1h; if (req.url ~ "(?i)\.(png|gif|ipeg|jpg|ico|swf|css|js)(\?[a-z0-9]+)?$") { unset beresp.http.set-cookie; } # Default Varnish VCL logic if (!beresp.cacheable || beresp.ttl <= 0s || beresp.http.Set-Cookie || beresp.http.Vary == "*") { set beresp.ttl = 120 s; return(hit_for_pass); } # Not Cacheable if it has specific TB_NC no-caching cookie if (req.http.Cookie && req.http.Cookie ~ "TB_NC") { set beresp.http.X-Cacheable = "NO:Got Cookie"; set beresp.ttl = 120 s; return(hit_for_pass); } # Not Cacheable if it has Cache-Control private else if (beresp.http.Cache-Control ~ "private") { set beresp.http.X-Cacheable = "NO:Cache-Control=private"; set beresp.ttl = 120 s; return(hit_for_pass); } # Not Cacheable if it has Cache-Control no-cache or Pragma no-cache else if (beresp.http.Cache-Control ~ "no-cache" || beresp.http.Pragma ~ "no-cache") { set beresp.http.X-Cacheable = "NO:Cache-Control=no-cache (or pragma no-cache)"; set beresp.ttl = 120 s; return(hit_for_pass); } # If we reach to this point, the object is cacheable. # Cacheable but with not enough ttl: we need to extend the lifetime of the object artificially # NOTE: Varnish default TTL is set in /etc/sysconfig/varnish # and can be checked using the following command: # varnishadm param.show default_ttl else if (beresp.ttl < 1s) { set beresp.ttl = 5s; set beresp.grace = 5s; set beresp.http.X-Cacheable = "YES:FORCED"; } # Cacheable and with valid TTL. else { set beresp.http.X-Cacheable = "YES"; } # DEBUG INFO (Cookies) # set beresp.http.X-Cookie-Debug = "Request cookie: " + req.http.Cookie; return(deliver); } sub vcl_error { set obj.http.Content-Type = "text/html; charset=utf-8"; if (obj.status == 404) { synthetic {" <!-- Markup for the 404 page goes here --> "}; } else if (obj.status == 500) { synthetic {" <!-- Markup for the 500 page goes here --> "}; } else if (obj.status == 503) { if (req.restarts < 4) { return(restart); } else { synthetic {" <!-- Markup for the 503 page goes here --> "}; } } else { synthetic {" <!-- Markup for a generic error page goes here --> "}; } } sub vcl_deliver { if (obj.hits > 0) { set resp.http.X-Cache = "HIT"; } else { set resp.http.X-Cache = "MISS"; } } Thanks in advance,

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• DNS works only with ip but does not work with NS CentOS + Bind9

  - by Borislav Yordanov

  I am having a headache with DNS. Lets say my public IP is 1.2.3.4, my local IP is 192.168.0.10 and my domain is example.com I am running CentOS on a virtual machine (Parallels Desktop for Mac) with a LAN card reserved for it, so it gets Ip directly from the router. I have ports 80,443,53 forwarded to 192.168.0.10. Both Mac OS and CentOs firewalls are Off. The strange is when I type dig @1.2.3.4 example.com from my other PC I get: ; <<>> DiG 9.8.3-P1 <<>> @1.2.3.4 example.com ; (1 server found) ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 16941 ;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2 ;; WARNING: recursion requested but not available ;; QUESTION SECTION: ;example.com. IN A ;; ANSWER SECTION: example.com. 86400 IN A 1.2.3.4 ;; AUTHORITY SECTION: example.com. 86400 IN NS ns2.example.com. example.com. 86400 IN NS ns1.example.com. ;; ADDITIONAL SECTION: ns1.example.com. 86400 IN A 1.2.3.4 ns2.example.com. 86400 IN A 1.2.3.4 ;; Query time: 8 msec ;; SERVER: 1.2.3.4#53(1.2.3.4) ;; WHEN: Sat Nov 2 09:37:36 2013 ;; MSG SIZE rcvd: 109 but when i type: dig @ns1.example.com example.com it waits a few seconds and returns dig: couldn't get address for 'ns1.dsht.in': not found This is my config file: /etc/named.conf options { listen-on-v6 { none; }; directory"/var/named"; dump-file"/var/named/data/cache_dump.db"; statistics-file"/var/named/data/named_stats.txt"; memstatistics-file"/var/named/data/named_mem_stats.txt"; allow-query{ localhost; 192.168.0.0/24; }; allow-transfer { localhost; 192.168.0.0/24; }; recursion yes; dnssec-enable yes; dnssec-validation yes; dnssec-lookaside auto; bindkeys-file "/etc/named.iscdlv.key"; managed-keys-directory "/var/named/dynamic"; }; logging { channel default_debug { file "data/named.run"; severity dynamic; }; }; # change all from here view "internal" { match-clients { localhost; 192.168.0.0/24; }; zone "." IN { type hint; file "named.ca"; }; zone "example.com" IN { type master; file "example.com.zone"; allow-update { none; }; }; zone "0.168.192.in-addr.arpa" IN { type master; file "0.168.192.in-addr.arpa"; allow-update { none; }; }; include "/etc/named.rfc1912.zones"; include "/etc/named.root.key"; }; view "external" { match-clients { any; }; allow-query { any; }; recursion no; zone "example.com" IN { type master; file "example.com.zone"; allow-update { none; }; }; zone "4.3.2.1.in-addr.arpa" IN { type master; file "4.3.2.1.in-addr.arpa"; allow-update { none; }; }; }; /var/named/exmaple.com.zone $TTL 86400 @ IN SOA ns1.example.com. host.example.com. ( 2013042201 ;Serial 3600 ;Refresh 1800 ;Retry 604800 ;Expire 86400 ;Minimum TTL ) ; Specify our two nameservers IN NS ns1.example.com. IN NS ns2.example.com. ; Resolve nameserver hostnames to IP, replace with your two droplet IP addresses. ns1 IN A 1.2.3.4 ns2 IN A 1.2.3.4 ; Define hostname -> IP pairs which you wish to resolve @ IN A 1.2.3.4 IN A 1.2.3.4 www IN A 1.2.3.4 server2 IN A 192.168.0.2 * IN A 1.2.3.4 /var/named/4.3.2.1.in-addr.arpa $TTL 2d ; 172800 seconds $ORIGIN 4.3.2.1.IN-ADDR.ARPA. @ IN SOA ns1.example.com. host.example.com. ( 2013010304 ; serial number 3h ; refresh 15m ; update retry 3w ; expiry 3h ; nx = nxdomain ttl ) IN NS ns1.example.com. IN NS ns2.example.com. IN PTR example.com. ; etc /var/named/0.168.192.in-addr.arpa $TTL 2d ; 172800 seconds $ORIGIN 0.168.192.IN-ADDR.ARPA. @ IN SOA ns1.example.com. host.example.com. ( 2013010304 ; serial number 3h ; refresh 15m ; update retry 3w ; expiry 3h ; nx = nxdomain ttl ) IN NS ns1.example.com. IN NS ns2.example.com. 10 IN PTR example.com. 2 IN PTR server2.example.com ; etc I will be very glad if someone can help me. Thank you in advance

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• Camera for 2.5D Game

  - by me--

  I'm hoping someone can explain this to me like I'm 5, because I've been struggling with this for hours and simply cannot understand what I'm doing wrong. I've written a Camera class for my 2.5D game. The intention is to support world and screen spaces like this: The camera is the black thing on the right. The +Z axis is upwards in that image, with -Z heading downwards. As you can see, both world space and screen space have (0, 0) at their top-left. I started writing some unit tests to prove that my camera was working as expected, and that's where things started getting...strange. My tests plot coordinates in world, view, and screen spaces. Eventually I will use image comparison to assert that they are correct, but for now my test just displays the result. The render logic uses Camera.ViewMatrix to transform world space to view space, and Camera.WorldPointToScreen to transform world space to screen space. Here is an example test: [Fact] public void foo() { var camera = new Camera(new Viewport(0, 0, 250, 100)); DrawingVisual worldRender; DrawingVisual viewRender; DrawingVisual screenRender; this.Render(camera, out worldRender, out viewRender, out screenRender, new Vector3(30, 0, 0), new Vector3(30, 40, 0)); this.ShowRenders(camera, worldRender, viewRender, screenRender); } And here's what pops up when I run this test: World space looks OK, although I suspect the z axis is going into the screen instead of towards the viewer. View space has me completely baffled. I was expecting the camera to be sitting above (0, 0) and looking towards the center of the scene. Instead, the z axis seems to be the wrong way around, and the camera is positioned in the opposite corner to what I expect! I suspect screen space will be another thing altogether, but can anyone explain what I'm doing wrong in my Camera class? UPDATE I made some progress in terms of getting things to look visually as I expect, but only through intuition: not an actual understanding of what I'm doing. Any enlightenment would be greatly appreciated. I realized that my view space was flipped both vertically and horizontally compared to what I expected, so I changed my view matrix to scale accordingly: this.viewMatrix = Matrix.CreateLookAt(this.location, this.target, this.up) * Matrix.CreateScale(this.zoom, this.zoom, 1) * Matrix.CreateScale(-1, -1, 1); I could combine the two CreateScale calls, but have left them separate for clarity. Again, I have no idea why this is necessary, but it fixed my view space: But now my screen space needs to be flipped vertically, so I modified my projection matrix accordingly: this.projectionMatrix = Matrix.CreatePerspectiveFieldOfView(0.7853982f, viewport.AspectRatio, 1, 2) * Matrix.CreateScale(1, -1, 1); And this results in what I was expecting from my first attempt: I have also just tried using Camera to render sprites via a SpriteBatch to make sure everything works there too, and it does. But the question remains: why do I need to do all this flipping of axes to get the space coordinates the way I expect? UPDATE 2 I've since improved my rendering logic in my test suite so that it supports geometries and so that lines get lighter the further away they are from the camera. I wanted to do this to avoid optical illusions and to further prove to myself that I'm looking at what I think I am. Here is an example: In this case, I have 3 geometries: a cube, a sphere, and a polyline on the top face of the cube. Notice how the darkening and lightening of the lines correctly identifies those portions of the geometries closer to the camera. If I remove the negative scaling I had to put in, I see: So you can see I'm still in the same boat - I still need those vertical and horizontal flips in my matrices to get things to appear correctly. In the interests of giving people a repro to play with, here is the complete code needed to generate the above. If you want to run via the test harness, just install the xunit package: Camera.cs: using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Graphics; using System.Diagnostics; public sealed class Camera { private readonly Viewport viewport; private readonly Matrix projectionMatrix; private Matrix? viewMatrix; private Vector3 location; private Vector3 target; private Vector3 up; private float zoom; public Camera(Viewport viewport) { this.viewport = viewport; // for an explanation of the negative scaling, see: http://gamedev.stackexchange.com/questions/63409/ this.projectionMatrix = Matrix.CreatePerspectiveFieldOfView(0.7853982f, viewport.AspectRatio, 1, 2) * Matrix.CreateScale(1, -1, 1); // defaults this.location = new Vector3(this.viewport.Width / 2, this.viewport.Height, 100); this.target = new Vector3(this.viewport.Width / 2, this.viewport.Height / 2, 0); this.up = new Vector3(0, 0, 1); this.zoom = 1; } public Viewport Viewport { get { return this.viewport; } } public Vector3 Location { get { return this.location; } set { this.location = value; this.viewMatrix = null; } } public Vector3 Target { get { return this.target; } set { this.target = value; this.viewMatrix = null; } } public Vector3 Up { get { return this.up; } set { this.up = value; this.viewMatrix = null; } } public float Zoom { get { return this.zoom; } set { this.zoom = value; this.viewMatrix = null; } } public Matrix ProjectionMatrix { get { return this.projectionMatrix; } } public Matrix ViewMatrix { get { if (this.viewMatrix == null) { // for an explanation of the negative scaling, see: http://gamedev.stackexchange.com/questions/63409/ this.viewMatrix = Matrix.CreateLookAt(this.location, this.target, this.up) * Matrix.CreateScale(this.zoom) * Matrix.CreateScale(-1, -1, 1); } return this.viewMatrix.Value; } } public Vector2 WorldPointToScreen(Vector3 point) { var result = viewport.Project(point, this.ProjectionMatrix, this.ViewMatrix, Matrix.Identity); return new Vector2(result.X, result.Y); } public void WorldPointsToScreen(Vector3[] points, Vector2[] destination) { Debug.Assert(points != null); Debug.Assert(destination != null); Debug.Assert(points.Length == destination.Length); for (var i = 0; i < points.Length; ++i) { destination[i] = this.WorldPointToScreen(points[i]); } } } CameraFixture.cs: using Microsoft.Xna.Framework.Graphics; using System; using System.Collections.Generic; using System.Linq; using System.Windows; using System.Windows.Controls; using System.Windows.Media; using Xunit; using XNA = Microsoft.Xna.Framework; public sealed class CameraFixture { [Fact] public void foo() { var camera = new Camera(new Viewport(0, 0, 250, 100)); DrawingVisual worldRender; DrawingVisual viewRender; DrawingVisual screenRender; this.Render( camera, out worldRender, out viewRender, out screenRender, new Sphere(30, 15) { WorldMatrix = XNA.Matrix.CreateTranslation(155, 50, 0) }, new Cube(30) { WorldMatrix = XNA.Matrix.CreateTranslation(75, 60, 15) }, new PolyLine(new XNA.Vector3(0, 0, 0), new XNA.Vector3(10, 10, 0), new XNA.Vector3(20, 0, 0), new XNA.Vector3(0, 0, 0)) { WorldMatrix = XNA.Matrix.CreateTranslation(65, 55, 30) }); this.ShowRenders(worldRender, viewRender, screenRender); } #region Supporting Fields private static readonly Pen xAxisPen = new Pen(Brushes.Red, 2); private static readonly Pen yAxisPen = new Pen(Brushes.Green, 2); private static readonly Pen zAxisPen = new Pen(Brushes.Blue, 2); private static readonly Pen viewportPen = new Pen(Brushes.Gray, 1); private static readonly Pen nonScreenSpacePen = new Pen(Brushes.Black, 0.5); private static readonly Color geometryBaseColor = Colors.Black; #endregion #region Supporting Methods private void Render(Camera camera, out DrawingVisual worldRender, out DrawingVisual viewRender, out DrawingVisual screenRender, params Geometry[] geometries) { var worldDrawingVisual = new DrawingVisual(); var viewDrawingVisual = new DrawingVisual(); var screenDrawingVisual = new DrawingVisual(); const int axisLength = 15; using (var worldDrawingContext = worldDrawingVisual.RenderOpen()) using (var viewDrawingContext = viewDrawingVisual.RenderOpen()) using (var screenDrawingContext = screenDrawingVisual.RenderOpen()) { // draw lines around the camera's viewport var viewportBounds = camera.Viewport.Bounds; var viewportLines = new Tuple<int, int, int, int>[] { Tuple.Create(viewportBounds.Left, viewportBounds.Bottom, viewportBounds.Left, viewportBounds.Top), Tuple.Create(viewportBounds.Left, viewportBounds.Top, viewportBounds.Right, viewportBounds.Top), Tuple.Create(viewportBounds.Right, viewportBounds.Top, viewportBounds.Right, viewportBounds.Bottom), Tuple.Create(viewportBounds.Right, viewportBounds.Bottom, viewportBounds.Left, viewportBounds.Bottom) }; foreach (var viewportLine in viewportLines) { var viewStart = XNA.Vector3.Transform(new XNA.Vector3(viewportLine.Item1, viewportLine.Item2, 0), camera.ViewMatrix); var viewEnd = XNA.Vector3.Transform(new XNA.Vector3(viewportLine.Item3, viewportLine.Item4, 0), camera.ViewMatrix); var screenStart = camera.WorldPointToScreen(new XNA.Vector3(viewportLine.Item1, viewportLine.Item2, 0)); var screenEnd = camera.WorldPointToScreen(new XNA.Vector3(viewportLine.Item3, viewportLine.Item4, 0)); worldDrawingContext.DrawLine(viewportPen, new Point(viewportLine.Item1, viewportLine.Item2), new Point(viewportLine.Item3, viewportLine.Item4)); viewDrawingContext.DrawLine(viewportPen, new Point(viewStart.X, viewStart.Y), new Point(viewEnd.X, viewEnd.Y)); screenDrawingContext.DrawLine(viewportPen, new Point(screenStart.X, screenStart.Y), new Point(screenEnd.X, screenEnd.Y)); } // draw axes var axisLines = new Tuple<int, int, int, int, int, int, Pen>[] { Tuple.Create(0, 0, 0, axisLength, 0, 0, xAxisPen), Tuple.Create(0, 0, 0, 0, axisLength, 0, yAxisPen), Tuple.Create(0, 0, 0, 0, 0, axisLength, zAxisPen) }; foreach (var axisLine in axisLines) { var viewStart = XNA.Vector3.Transform(new XNA.Vector3(axisLine.Item1, axisLine.Item2, axisLine.Item3), camera.ViewMatrix); var viewEnd = XNA.Vector3.Transform(new XNA.Vector3(axisLine.Item4, axisLine.Item5, axisLine.Item6), camera.ViewMatrix); var screenStart = camera.WorldPointToScreen(new XNA.Vector3(axisLine.Item1, axisLine.Item2, axisLine.Item3)); var screenEnd = camera.WorldPointToScreen(new XNA.Vector3(axisLine.Item4, axisLine.Item5, axisLine.Item6)); worldDrawingContext.DrawLine(axisLine.Item7, new Point(axisLine.Item1, axisLine.Item2), new Point(axisLine.Item4, axisLine.Item5)); viewDrawingContext.DrawLine(axisLine.Item7, new Point(viewStart.X, viewStart.Y), new Point(viewEnd.X, viewEnd.Y)); screenDrawingContext.DrawLine(axisLine.Item7, new Point(screenStart.X, screenStart.Y), new Point(screenEnd.X, screenEnd.Y)); } // for all points in all geometries to be rendered, find the closest and furthest away from the camera so we can lighten lines that are further away var distancesToAllGeometrySections = from geometry in geometries let geometryViewMatrix = geometry.WorldMatrix * camera.ViewMatrix from section in geometry.Sections from point in new XNA.Vector3[] { section.Item1, section.Item2 } let viewPoint = XNA.Vector3.Transform(point, geometryViewMatrix) select viewPoint.Length(); var furthestDistance = distancesToAllGeometrySections.Max(); var closestDistance = distancesToAllGeometrySections.Min(); var deltaDistance = Math.Max(0.000001f, furthestDistance - closestDistance); // draw each geometry for (var i = 0; i < geometries.Length; ++i) { var geometry = geometries[i]; // there's probably a more correct name for this, but basically this gets the geometry relative to the camera so we can check how far away each point is from the camera var geometryViewMatrix = geometry.WorldMatrix * camera.ViewMatrix; // we order roughly by those sections furthest from the camera to those closest, so that the closer ones "overwrite" the ones further away var orderedSections = from section in geometry.Sections let startPointRelativeToCamera = XNA.Vector3.Transform(section.Item1, geometryViewMatrix) let endPointRelativeToCamera = XNA.Vector3.Transform(section.Item2, geometryViewMatrix) let startPointDistance = startPointRelativeToCamera.Length() let endPointDistance = endPointRelativeToCamera.Length() orderby (startPointDistance + endPointDistance) descending select new { Section = section, DistanceToStart = startPointDistance, DistanceToEnd = endPointDistance }; foreach (var orderedSection in orderedSections) { var start = XNA.Vector3.Transform(orderedSection.Section.Item1, geometry.WorldMatrix); var end = XNA.Vector3.Transform(orderedSection.Section.Item2, geometry.WorldMatrix); var viewStart = XNA.Vector3.Transform(start, camera.ViewMatrix); var viewEnd = XNA.Vector3.Transform(end, camera.ViewMatrix); worldDrawingContext.DrawLine(nonScreenSpacePen, new Point(start.X, start.Y), new Point(end.X, end.Y)); viewDrawingContext.DrawLine(nonScreenSpacePen, new Point(viewStart.X, viewStart.Y), new Point(viewEnd.X, viewEnd.Y)); // screen rendering is more complicated purely because I wanted geometry to fade the further away it is from the camera // otherwise, it's very hard to tell whether the rendering is actually correct or not var startDistanceRatio = (orderedSection.DistanceToStart - closestDistance) / deltaDistance; var endDistanceRatio = (orderedSection.DistanceToEnd - closestDistance) / deltaDistance; // lerp towards white based on distance from camera, but only to a maximum of 90% var startColor = Lerp(geometryBaseColor, Colors.White, startDistanceRatio * 0.9f); var endColor = Lerp(geometryBaseColor, Colors.White, endDistanceRatio * 0.9f); var screenStart = camera.WorldPointToScreen(start); var screenEnd = camera.WorldPointToScreen(end); var brush = new LinearGradientBrush { StartPoint = new Point(screenStart.X, screenStart.Y), EndPoint = new Point(screenEnd.X, screenEnd.Y), MappingMode = BrushMappingMode.Absolute }; brush.GradientStops.Add(new GradientStop(startColor, 0)); brush.GradientStops.Add(new GradientStop(endColor, 1)); var pen = new Pen(brush, 1); brush.Freeze(); pen.Freeze(); screenDrawingContext.DrawLine(pen, new Point(screenStart.X, screenStart.Y), new Point(screenEnd.X, screenEnd.Y)); } } } worldRender = worldDrawingVisual; viewRender = viewDrawingVisual; screenRender = screenDrawingVisual; } private static float Lerp(float start, float end, float amount) { var difference = end - start; var adjusted = difference * amount; return start + adjusted; } private static Color Lerp(Color color, Color to, float amount) { var sr = color.R; var sg = color.G; var sb = color.B; var er = to.R; var eg = to.G; var eb = to.B; var r = (byte)Lerp(sr, er, amount); var g = (byte)Lerp(sg, eg, amount); var b = (byte)Lerp(sb, eb, amount); return Color.FromArgb(255, r, g, b); } private void ShowRenders(DrawingVisual worldRender, DrawingVisual viewRender, DrawingVisual screenRender) { var itemsControl = new ItemsControl(); itemsControl.Items.Add(new HeaderedContentControl { Header = "World", Content = new DrawingVisualHost(worldRender)}); itemsControl.Items.Add(new HeaderedContentControl { Header = "View", Content = new DrawingVisualHost(viewRender) }); itemsControl.Items.Add(new HeaderedContentControl { Header = "Screen", Content = new DrawingVisualHost(screenRender) }); var window = new Window { Title = "Renders", Content = itemsControl, ShowInTaskbar = true, SizeToContent = SizeToContent.WidthAndHeight }; window.ShowDialog(); } #endregion #region Supporting Types // stupidly simple 3D geometry class, consisting of a series of sections that will be connected by lines private abstract class Geometry { public abstract IEnumerable<Tuple<XNA.Vector3, XNA.Vector3>> Sections { get; } public XNA.Matrix WorldMatrix { get; set; } } private sealed class Line : Geometry { private readonly XNA.Vector3 magnitude; public Line(XNA.Vector3 magnitude) { this.magnitude = magnitude; } public override IEnumerable<Tuple<XNA.Vector3, XNA.Vector3>> Sections { get { yield return Tuple.Create(XNA.Vector3.Zero, this.magnitude); } } } private sealed class PolyLine : Geometry { private readonly XNA.Vector3[] points; public PolyLine(params XNA.Vector3[] points) { this.points = points; } public override IEnumerable<Tuple<XNA.Vector3, XNA.Vector3>> Sections { get { if (this.points.Length < 2) { yield break; } var end = this.points[0]; for (var i = 1; i < this.points.Length; ++i) { var start = end; end = this.points[i]; yield return Tuple.Create(start, end); } } } } private sealed class Cube : Geometry { private readonly float size; public Cube(float size) { this.size = size; } public override IEnumerable<Tuple<XNA.Vector3, XNA.Vector3>> Sections { get { var halfSize = this.size / 2; var frontBottomLeft = new XNA.Vector3(-halfSize, halfSize, -halfSize); var frontBottomRight = new XNA.Vector3(halfSize, halfSize, -halfSize); var frontTopLeft = new XNA.Vector3(-halfSize, halfSize, halfSize); var frontTopRight = new XNA.Vector3(halfSize, halfSize, halfSize); var backBottomLeft = new XNA.Vector3(-halfSize, -halfSize, -halfSize); var backBottomRight = new XNA.Vector3(halfSize, -halfSize, -halfSize); var backTopLeft = new XNA.Vector3(-halfSize, -halfSize, halfSize); var backTopRight = new XNA.Vector3(halfSize, -halfSize, halfSize); // front face yield return Tuple.Create(frontBottomLeft, frontBottomRight); yield return Tuple.Create(frontBottomLeft, frontTopLeft); yield return Tuple.Create(frontTopLeft, frontTopRight); yield return Tuple.Create(frontTopRight, frontBottomRight); // left face yield return Tuple.Create(frontTopLeft, backTopLeft); yield return Tuple.Create(backTopLeft, backBottomLeft); yield return Tuple.Create(backBottomLeft, frontBottomLeft); // right face yield return Tuple.Create(frontTopRight, backTopRight); yield return Tuple.Create(backTopRight, backBottomRight); yield return Tuple.Create(backBottomRight, frontBottomRight); // back face yield return Tuple.Create(backBottomLeft, backBottomRight); yield return Tuple.Create(backTopLeft, backTopRight); } } } private sealed class Sphere : Geometry { private readonly float radius; private readonly int subsections; public Sphere(float radius, int subsections) { this.radius = radius; this.subsections = subsections; } public override IEnumerable<Tuple<XNA.Vector3, XNA.Vector3>> Sections { get { var latitudeLines = this.subsections; var longitudeLines = this.subsections; // see http://stackoverflow.com/a/4082020/5380 var results = from latitudeLine in Enumerable.Range(0, latitudeLines) from longitudeLine in Enumerable.Range(0, longitudeLines) let latitudeRatio = latitudeLine / (float)latitudeLines let longitudeRatio = longitudeLine / (float)longitudeLines let nextLatitudeRatio = (latitudeLine + 1) / (float)latitudeLines let nextLongitudeRatio = (longitudeLine + 1) / (float)longitudeLines let z1 = Math.Cos(Math.PI * latitudeRatio) let z2 = Math.Cos(Math.PI * nextLatitudeRatio) let x1 = Math.Sin(Math.PI * latitudeRatio) * Math.Cos(Math.PI * 2 * longitudeRatio) let y1 = Math.Sin(Math.PI * latitudeRatio) * Math.Sin(Math.PI * 2 * longitudeRatio) let x2 = Math.Sin(Math.PI * nextLatitudeRatio) * Math.Cos(Math.PI * 2 * longitudeRatio) let y2 = Math.Sin(Math.PI * nextLatitudeRatio) * Math.Sin(Math.PI * 2 * longitudeRatio) let x3 = Math.Sin(Math.PI * latitudeRatio) * Math.Cos(Math.PI * 2 * nextLongitudeRatio) let y3 = Math.Sin(Math.PI * latitudeRatio) * Math.Sin(Math.PI * 2 * nextLongitudeRatio) let start = new XNA.Vector3((float)x1 * radius, (float)y1 * radius, (float)z1 * radius) let firstEnd = new XNA.Vector3((float)x2 * radius, (float)y2 * radius, (float)z2 * radius) let secondEnd = new XNA.Vector3((float)x3 * radius, (float)y3 * radius, (float)z1 * radius) select new { First = Tuple.Create(start, firstEnd), Second = Tuple.Create(start, secondEnd) }; foreach (var result in results) { yield return result.First; yield return result.Second; } } } } #endregion }

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• Red Gate Coder interviews: Alex Davies

  - by Michael Williamson

  Alex Davies has been a software engineer at Red Gate since graduating from university, and is currently busy working on .NET Demon. We talked about tackling parallel programming with his actors framework, a scientific approach to debugging, and how JavaScript is going to affect the programming languages we use in years to come. So, if we start at the start, how did you get started in programming? When I was seven or eight, I was given a BBC Micro for Christmas. I had asked for a Game Boy, but my dad thought it would be better to give me a proper computer. For a year or so, I only played games on it, but then I found the user guide for writing programs in it. I gradually started doing more stuff on it and found it fun. I liked creating. As I went into senior school I continued to write stuff on there, trying to write games that weren’t very good. I got a real computer when I was fourteen and found ways to write BASIC on it. Visual Basic to start with, and then something more interesting than that. How did you learn to program? Was there someone helping you out? Absolutely not! I learnt out of a book, or by experimenting. I remember the first time I found a loop, I was like “Oh my God! I don’t have to write out the same line over and over and over again any more. It’s amazing!” When did you think this might be something that you actually wanted to do as a career? For a long time, I thought it wasn’t something that you would do as a career, because it was too much fun to be a career. I thought I’d do chemistry at university and some kind of career based on chemical engineering. And then I went to a careers fair at school when I was seventeen or eighteen, and it just didn’t interest me whatsoever. I thought “I could be a programmer, and there’s loads of money there, and I’m good at it, and it’s fun”, but also that I shouldn’t spoil my hobby. Now I don’t really program in my spare time any more, which is a bit of a shame, but I program all the rest of the time, so I can live with it. Do you think you learnt much about programming at university? Yes, definitely! I went into university knowing how to make computers do anything I wanted them to do. However, I didn’t have the language to talk about algorithms, so the algorithms course in my first year was massively important. Learning other language paradigms like functional programming was really good for breadth of understanding. Functional programming influences normal programming through design rather than actually using it all the time. I draw inspiration from it to write imperative programs which I think is actually becoming really fashionable now, but I’ve been doing it for ages. I did it first! There were also some courses on really odd programming languages, a bit of Prolog, a little bit of C. Having a little bit of each of those is something that I would have never done on my own, so it was important. And then there are knowledge-based courses which are about not programming itself but things that have been programmed like TCP. Those are really important for examples for how to approach things. Did you do any internships while you were at university? Yeah, I spent both of my summers at the same company. I thought I could code well before I went there. Looking back at the crap that I produced, it was only surpassed in its crappiness by all of the other code already in that company. I’m so much better at writing nice code now than I used to be back then. Was there just not a culture of looking after your code? There was, they just didn’t hire people for their abilities in that area. They hired people for raw IQ. The first indicator of it going wrong was that they didn’t have any computer scientists, which is a bit odd in a programming company. But even beyond that they didn’t have people who learnt architecture from anyone else. Most of them had started straight out of university, so never really had experience or mentors to learn from. There wasn’t the experience to draw from to teach each other. In the second half of my second internship, I was being given tasks like looking at new technologies and teaching people stuff. Interns shouldn’t be teaching people how to do their jobs! All interns are going to have little nuggets of things that you don’t know about, but they shouldn’t consistently be the ones who know the most. It’s not a good environment to learn. I was going to ask how you found working with people who were more experienced than you… When I reached Red Gate, I found some people who were more experienced programmers than me, and that was difficult. I’ve been coding since I was tiny. At university there were people who were cleverer than me, but there weren’t very many who were more experienced programmers than me. During my internship, I didn’t find anyone who I classed as being a noticeably more experienced programmer than me. So, it was a shock to the system to have valid criticisms rather than just formatting criticisms. However, Red Gate’s not so big on the actual code review, at least it wasn’t when I started. We did an entire product release and then somebody looked over all of the UI of that product which I’d written and say what they didn’t like. By that point, it was way too late and I’d disagree with them. Do you think the lack of code reviews was a bad thing? I think if there’s going to be any oversight of new people, then it should be continuous rather than chunky. For me I don’t mind too much, I could go out and get oversight if I wanted it, and in those situations I felt comfortable without it. If I was managing the new person, then maybe I’d be keener on oversight and then the right way to do it is continuously and in very, very small chunks. Have you had any significant projects you’ve worked on outside of a job? When I was a teenager I wrote all sorts of stuff. I used to write games, I derived how to do isomorphic projections myself once. I didn’t know what the word was so I couldn’t Google for it, so I worked it out myself. It was horrifically complicated. But it sort of tailed off when I started at university, and is now basically zero. If I do side-projects now, they tend to be work-related side projects like my actors framework, NAct, which I started in a down tools week. Could you explain a little more about NAct? It is a little C# framework for writing parallel code more easily. Parallel programming is difficult when you need to write to shared data. Sometimes parallel programming is easy because you don’t need to write to shared data. When you do need to access shared data, you could just have your threads pile in and do their work, but then you would screw up the data because the threads would trample on each other’s toes. You could lock, but locks are really dangerous if you’re using more than one of them. You get interactions like deadlocks, and that’s just nasty. Actors instead allows you to say this piece of data belongs to this thread of execution, and nobody else can read it. If you want to read it, then ask that thread of execution for a piece of it by sending a message, and it will send the data back by a message. And that avoids deadlocks as long as you follow some obvious rules about not making your actors sit around waiting for other actors to do something. There are lots of ways to write actors, NAct allows you to do it as if it was method calls on other objects, which means you get all the strong type-safety that C# programmers like. Do you think that this is suitable for the majority of parallel programming, or do you think it’s only suitable for specific cases? It’s suitable for most difficult parallel programming. If you’ve just got a hundred web requests which are all independent of each other, then I wouldn’t bother because it’s easier to just spin them up in separate threads and they can proceed independently of each other. But where you’ve got difficult parallel programming, where you’ve got multiple threads accessing multiple bits of data in multiple ways at different times, then actors is at least as good as all other ways, and is, I reckon, easier to think about. When you’re using actors, you presumably still have to write your code in a different way from you would otherwise using single-threaded code. You can’t use actors with any methods that have return types, because you’re not allowed to call into another actor and wait for it. If you want to get a piece of data out of another actor, then you’ve got to use tasks so that you can use “async” and “await” to await asynchronously for it. But other than that, you can still stick things in classes so it’s not too different really. Rather than having thousands of objects with mutable state, you can use component-orientated design, where there are only a few mutable classes which each have a small number of instances. Then there can be thousands of immutable objects. If you tend to do that anyway, then actors isn’t much of a jump. If I’ve already built my system without any parallelism, how hard is it to add actors to exploit all eight cores on my desktop? Usually pretty easy. If you can identify even one boundary where things look like messages and you have components where some objects live on one side and these other objects live on the other side, then you can have a granddaddy object on one side be an actor and it will parallelise as it goes across that boundary. Not too difficult. If we do get 1000-core desktop PCs, do you think actors will scale up? It’s hard. There are always in the order of twenty to fifty actors in my whole program because I tend to write each component as actors, and I tend to have one instance of each component. So this won’t scale to a thousand cores. What you can do is write data structures out of actors. I use dictionaries all over the place, and if you need a dictionary that is going to be accessed concurrently, then you could build one of those out of actors in no time. You can use queuing to marshal requests between different slices of the dictionary which are living on different threads. So it’s like a distributed hash table but all of the chunks of it are on the same machine. That means that each of these thousand processors has cached one small piece of the dictionary. I reckon it wouldn’t be too big a leap to start doing proper parallelism. Do you think it helps if actors get baked into the language, similarly to Erlang? Erlang is excellent in that it has thread-local garbage collection. C# doesn’t, so there’s a limit to how well C# actors can possibly scale because there’s a single garbage collected heap shared between all of them. When you do a global garbage collection, you’ve got to stop all of the actors, which is seriously expensive, whereas in Erlang garbage collections happen per-actor, so they’re insanely cheap. However, Erlang deviated from all the sensible language design that people have used recently and has just come up with crazy stuff. You can definitely retrofit thread-local garbage collection to .NET, and then it’s quite well-suited to support actors, even if it’s not baked into the language. Speaking of language design, do you have a favourite programming language? I’ll choose a language which I’ve never written before. I like the idea of Scala. It sounds like C#, only with some of the niggles gone. I enjoy writing static types. It means you don’t have to writing tests so much. When you say it doesn’t have some of the niggles? C# doesn’t allow the use of a property as a method group. It doesn’t have Scala case classes, or sum types, where you can do a switch statement and the compiler checks that you’ve checked all the cases, which is really useful in functional-style programming. Pattern-matching, in other words. That’s actually the major niggle. C# is pretty good, and I’m quite happy with C#. And what about going even further with the type system to remove the need for tests to something like Haskell? Or is that a step too far? I’m quite a pragmatist, I don’t think I could deal with trying to write big systems in languages with too few other users, especially when learning how to structure things. I just don’t know anyone who can teach me, and the Internet won’t teach me. That’s the main reason I wouldn’t use it. If I turned up at a company that writes big systems in Haskell, I would have no objection to that, but I wouldn’t instigate it. What about things in C#? For instance, there’s contracts in C#, so you can try to statically verify a bit more about your code. Do you think that’s useful, or just not worthwhile? I’ve not really tried it. My hunch is that it needs to be built into the language and be quite mathematical for it to work in real life, and that doesn’t seem to have ended up true for C# contracts. I don’t think anyone who’s tried them thinks they’re any good. I might be wrong. On a slightly different note, how do you like to debug code? I think I’m quite an odd debugger. I use guesswork extremely rarely, especially if something seems quite difficult to debug. I’ve been bitten spending hours and hours on guesswork and not being scientific about debugging in the past, so now I’m scientific to a fault. What I want is to see the bug happening in the debugger, to step through the bug happening. To watch the program going from a valid state to an invalid state. When there’s a bug and I can’t work out why it’s happening, I try to find some piece of evidence which places the bug in one section of the code. From that experiment, I binary chop on the possible causes of the bug. I suppose that means binary chopping on places in the code, or binary chopping on a stage through a processing cycle. Basically, I’m very stupid about how I debug. I won’t make any guesses, I won’t use any intuition, I will only identify the experiment that’s going to binary chop most effectively and repeat rather than trying to guess anything. I suppose it’s quite top-down. Is most of the time then spent in the debugger? Absolutely, if at all possible I will never debug using print statements or logs. I don’t really hold much stock in outputting logs. If there’s any bug which can be reproduced locally, I’d rather do it in the debugger than outputting logs. And with SmartAssembly error reporting, there’s not a lot that can’t be either observed in an error report and just fixed, or reproduced locally. And in those other situations, maybe I’ll use logs. But I hate using logs. You stare at the log, trying to guess what’s going on, and that’s exactly what I don’t like doing. You have to just look at it and see does this look right or wrong. We’ve covered how you get to grip with bugs. How do you get to grips with an entire codebase? I watch it in the debugger. I find little bugs and then try to fix them, and mostly do it by watching them in the debugger and gradually getting an understanding of how the code works using my process of binary chopping. I have to do a lot of reading and watching code to choose where my slicing-in-half experiment is going to be. The last time I did it was SmartAssembly. The old code was a complete mess, but at least it did things top to bottom. There wasn’t too much of some of the big abstractions where flow of control goes all over the place, into a base class and back again. Code’s really hard to understand when that happens. So I like to choose a little bug and try to fix it, and choose a bigger bug and try to fix it. Definitely learn by doing. I want to always have an aim so that I get a little achievement after every few hours of debugging. Once I’ve learnt the codebase I might be able to fix all the bugs in an hour, but I’d rather be using them as an aim while I’m learning the codebase. If I was a maintainer of a codebase, what should I do to make it as easy as possible for you to understand? Keep distinct concepts in different places. And name your stuff so that it’s obvious which concepts live there. You shouldn’t have some variable that gets set miles up the top of somewhere, and then is read miles down to choose some later behaviour. I’m talking from a very much SmartAssembly point of view because the old SmartAssembly codebase had tons and tons of these things, where it would read some property of the code and then deal with it later. Just thousands of variables in scope. Loads of things to think about. If you can keep concepts separate, then it aids me in my process of fixing bugs one at a time, because each bug is going to more or less be understandable in the one place where it is. And what about tests? Do you think they help at all? I’ve never had the opportunity to learn a codebase which has had tests, I don’t know what it’s like! What about when you’re actually developing? How useful do you find tests in finding bugs or regressions? Finding regressions, absolutely. Running bits of code that would be quite hard to run otherwise, definitely. It doesn’t happen very often that a test finds a bug in the first place. I don’t really buy nebulous promises like tests being a good way to think about the spec of the code. My thinking goes something like “This code works at the moment, great, ship it! Ah, there’s a way that this code doesn’t work. Okay, write a test, demonstrate that it doesn’t work, fix it, use the test to demonstrate that it’s now fixed, and keep the test for future regressions.” The most valuable tests are for bugs that have actually happened at some point, because bugs that have actually happened at some point, despite the fact that you think you’ve fixed them, are way more likely to appear again than new bugs are. Does that mean that when you write your code the first time, there are no tests? Often. The chance of there being a bug in a new feature is relatively unaffected by whether I’ve written a test for that new feature because I’m not good enough at writing tests to think of bugs that I would have written into the code. So not writing regression tests for all of your code hasn’t affected you too badly? There are different kinds of features. Some of them just always work, and are just not flaky, they just continue working whatever you throw at them. Maybe because the type-checker is particularly effective around them. Writing tests for those features which just tend to always work is a waste of time. And because it’s a waste of time I’ll tend to wait until a feature has demonstrated its flakiness by having bugs in it before I start trying to test it. You can get a feel for whether it’s going to be flaky code as you’re writing it. I try to write it to make it not flaky, but there are some things that are just inherently flaky. And very occasionally, I’ll think “this is going to be flaky” as I’m writing, and then maybe do a test, but not most of the time. How do you think your programming style has changed over time? I’ve got clearer about what the right way of doing things is. I used to flip-flop a lot between different ideas. Five years ago I came up with some really good ideas and some really terrible ideas. All of them seemed great when I thought of them, but they were quite diverse ideas, whereas now I have a smaller set of reliable ideas that are actually good for structuring code. So my code is probably more similar to itself than it used to be back in the day, when I was trying stuff out. I’ve got more disciplined about encapsulation, I think. There are operational things like I use actors more now than I used to, and that forces me to use immutability more than I used to. The first code that I wrote in Red Gate was the memory profiler UI, and that was an actor, I just didn’t know the name of it at the time. I don’t really use object-orientation. By object-orientation, I mean having n objects of the same type which are mutable. I want a constant number of objects that are mutable, and they should be different types. I stick stuff in dictionaries and then have one thing that owns the dictionary and puts stuff in and out of it. That’s definitely a pattern that I’ve seen recently. I think maybe I’m doing functional programming. Possibly. It’s plausible. If you had to summarise the essence of programming in a pithy sentence, how would you do it? Programming is the form of art that, without losing any of the beauty of architecture or fine art, allows you to produce things that people love and you make money from. So you think it’s an art rather than a science? It’s a little bit of engineering, a smidgeon of maths, but it’s not science. Like architecture, programming is on that boundary between art and engineering. If you want to do it really nicely, it’s mostly art. You can get away with doing architecture and programming entirely by having a good engineering mind, but you’re not going to produce anything nice. You’re not going to have joy doing it if you’re an engineering mind. Architects who are just engineering minds are not going to enjoy their job. I suppose engineering is the foundation on which you build the art. Exactly. How do you think programming is going to change over the next ten years? There will be an unfortunate shift towards dynamically-typed languages, because of JavaScript. JavaScript has an unfair advantage. JavaScript’s unfair advantage will cause more people to be exposed to dynamically-typed languages, which means other dynamically-typed languages crop up and the best features go into dynamically-typed languages. Then people conflate the good features with the fact that it’s dynamically-typed, and more investment goes into dynamically-typed languages. They end up better, so people use them. What about the idea of compiling other languages, possibly statically-typed, to JavaScript? It’s a reasonable idea. I would like to do it, but I don’t think enough people in the world are going to do it to make it pick up. The hordes of beginners are the lifeblood of a language community. They are what makes there be good tools and what makes there be vibrant community websites. And any particular thing which is the same as JavaScript only with extra stuff added to it, although it might be technically great, is not going to have the hordes of beginners. JavaScript is always to be quickest and easiest way for a beginner to start programming in the browser. And dynamically-typed languages are great for beginners. Compilers are pretty scary and beginners don’t write big code. And having your errors come up in the same place, whether they’re statically checkable errors or not, is quite nice for a beginner. If someone asked me to teach them some programming, I’d teach them JavaScript. If dynamically-typed languages are great for beginners, when do you think the benefits of static typing start to kick in? The value of having a statically typed program is in the tools that rely on the static types to produce a smooth IDE experience rather than actually telling me my compile errors. And only once you’re experienced enough a programmer that having a really smooth IDE experience makes a blind bit of difference, does static typing make a blind bit of difference. So it’s not really about size of codebase. If I go and write up a tiny program, I’m still going to get value out of writing it in C# using ReSharper because I’m experienced with C# and ReSharper enough to be able to write code five times faster if I have that help. Any other visions of the future? Nobody’s going to use actors. Because everyone’s going to be running on single-core VMs connected over network-ready protocols like JSON over HTTP. So, parallelism within one operating system is going to die. But until then, you should use actors. More Red Gater Coder interviews

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• TCP packets larger than 4 KB don't get a reply from Linux

  - by pts

  I'm running Linux 3.2.51 in a virtual machine (192.168.33.15). I'm sending Ethernet frames to it. I'm writing custom software trying to emulate a TCP peer, the other peer is Linux running in the virtual machine guest. I've noticed that TCP packets larger than about 4 KB are ignored (i.e. dropped without an ACK) by the Linux guest. If I decrease the packet size by 50 bytes, I get an ACK. I'm not sending new payload data until the Linux guest fully ACKs the previous one. I've increased ifconfig eth0 mtu 51000, and ping -c 1 -s 50000 goes through (from guest to my emulator) and the Linux guest gets a reply of the same size. I've also increased sysctl -w net.ipv4.tcp_rmem='70000 87380 87380 and tried with sysctl -w net.ipv4.tcp_mtu_probing=1 (and also =0). There is no IPv3 packet fragmentation, all packets have the DF flag set. It works the other way round: the Linux guest can send TCP packets of 6900 bytes of payload and my emulator understands them. This is very strange to me, because only TCP packets seem to be affected (large ICMP packets go through). Any idea what can be imposing this limit? Any idea how to do debug it in the Linux kernel? See the tcpdump -n -vv output below. tcpdump was run on the Linux guest. The last line is interesting: 4060 bytes of TCP payload is sent to the guest, and it doesn't get any reply packet from the Linux guest for half a minute. 14:59:32.000057 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.1.36522 > 192.168.33.15.22: Flags [S], cksum 0x8da0 (correct), seq 10000000, win 14600, length 0 14:59:32.000086 IP (tos 0x10, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 44) 192.168.33.15.22 > 192.168.33.1.36522: Flags [S.], cksum 0xc37f (incorrect -> 0x5999), seq 1415680476, ack 10000001, win 19920, options [mss 9960], length 0 14:59:32.000218 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.1.36522 > 192.168.33.15.22: Flags [.], cksum 0xa752 (correct), ack 1, win 14600, length 0 14:59:32.000948 IP (tos 0x10, ttl 64, id 53777, offset 0, flags [DF], proto TCP (6), length 66) 192.168.33.15.22 > 192.168.33.1.36522: Flags [P.], cksum 0xc395 (incorrect -> 0xfa01), seq 1:27, ack 1, win 19920, length 26 14:59:32.001575 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.1.36522 > 192.168.33.15.22: Flags [.], cksum 0xa738 (correct), ack 27, win 14600, length 0 14:59:32.001585 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 65) 192.168.33.1.36522 > 192.168.33.15.22: Flags [P.], cksum 0x48d6 (correct), seq 1:26, ack 27, win 14600, length 25 14:59:32.001589 IP (tos 0x10, ttl 64, id 53778, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.15.22 > 192.168.33.1.36522: Flags [.], cksum 0xc37b (incorrect -> 0x9257), ack 26, win 19920, length 0 14:59:32.001680 IP (tos 0x10, ttl 64, id 53779, offset 0, flags [DF], proto TCP (6), length 496) 192.168.33.15.22 > 192.168.33.1.36522: Flags [P.], seq 27:483, ack 26, win 19920, length 456 14:59:32.001784 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.1.36522 > 192.168.33.15.22: Flags [.], cksum 0xa557 (correct), ack 483, win 14600, length 0 14:59:32.006367 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 1136) 192.168.33.1.36522 > 192.168.33.15.22: Flags [P.], seq 26:1122, ack 483, win 14600, length 1096 14:59:32.044150 IP (tos 0x10, ttl 64, id 53780, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.15.22 > 192.168.33.1.36522: Flags [.], cksum 0xc37b (incorrect -> 0x8c47), ack 1122, win 19920, length 0 14:59:32.045310 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 312) 192.168.33.1.36522 > 192.168.33.15.22: Flags [P.], seq 1122:1394, ack 483, win 14600, length 272 14:59:32.045322 IP (tos 0x10, ttl 64, id 53781, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.15.22 > 192.168.33.1.36522: Flags [.], cksum 0xc37b (incorrect -> 0x8b37), ack 1394, win 19920, length 0 14:59:32.925726 IP (tos 0x10, ttl 64, id 53782, offset 0, flags [DF], proto TCP (6), length 1112) 192.168.33.15.22 > 192.168.33.1.36522: Flags [.], seq 483:1555, ack 1394, win 19920, length 1072 14:59:32.925750 IP (tos 0x10, ttl 64, id 53784, offset 0, flags [DF], proto TCP (6), length 312) 192.168.33.15.22 > 192.168.33.1.36522: Flags [P.], seq 1555:1827, ack 1394, win 19920, length 272 14:59:32.927131 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.1.36522 > 192.168.33.15.22: Flags [.], cksum 0x9bcf (correct), ack 1555, win 14600, length 0 14:59:32.927148 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.1.36522 > 192.168.33.15.22: Flags [.], cksum 0x9abf (correct), ack 1827, win 14600, length 0 14:59:32.932248 IP (tos 0x10, ttl 64, id 53785, offset 0, flags [DF], proto TCP (6), length 56) 192.168.33.15.22 > 192.168.33.1.36522: Flags [P.], cksum 0xc38b (incorrect -> 0xd247), seq 1827:1843, ack 1394, win 19920, length 16 14:59:32.932366 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.1.36522 > 192.168.33.15.22: Flags [.], cksum 0x9aaf (correct), ack 1843, win 14600, length 0 14:59:32.964295 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 104) 192.168.33.1.36522 > 192.168.33.15.22: Flags [P.], seq 1394:1458, ack 1843, win 14600, length 64 14:59:32.964310 IP (tos 0x10, ttl 64, id 53786, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.15.22 > 192.168.33.1.36522: Flags [.], cksum 0xc37b (incorrect -> 0x85a7), ack 1458, win 19920, length 0 14:59:32.964561 IP (tos 0x10, ttl 64, id 53787, offset 0, flags [DF], proto TCP (6), length 88) 192.168.33.15.22 > 192.168.33.1.36522: Flags [P.], seq 1843:1891, ack 1458, win 19920, length 48 14:59:32.965185 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.1.36522 > 192.168.33.15.22: Flags [.], cksum 0x9a3f (correct), ack 1891, win 14600, length 0 14:59:32.965196 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 104) 192.168.33.1.36522 > 192.168.33.15.22: Flags [P.], seq 1458:1522, ack 1891, win 14600, length 64 14:59:32.965233 IP (tos 0x10, ttl 64, id 53788, offset 0, flags [DF], proto TCP (6), length 88) 192.168.33.15.22 > 192.168.33.1.36522: Flags [P.], seq 1891:1939, ack 1522, win 19920, length 48 14:59:32.965970 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.1.36522 > 192.168.33.15.22: Flags [.], cksum 0x99cf (correct), ack 1939, win 14600, length 0 14:59:32.965979 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 568) 192.168.33.1.36522 > 192.168.33.15.22: Flags [P.], seq 1522:2050, ack 1939, win 14600, length 528 14:59:32.966112 IP (tos 0x10, ttl 64, id 53789, offset 0, flags [DF], proto TCP (6), length 520) 192.168.33.15.22 > 192.168.33.1.36522: Flags [P.], seq 1939:2419, ack 2050, win 19920, length 480 14:59:32.970059 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.1.36522 > 192.168.33.15.22: Flags [.], cksum 0x95df (correct), ack 2419, win 14600, length 0 14:59:32.970089 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 616) 192.168.33.1.36522 > 192.168.33.15.22: Flags [P.], seq 2050:2626, ack 2419, win 14600, length 576 14:59:32.981159 IP (tos 0x10, ttl 64, id 53790, offset 0, flags [DF], proto TCP (6), length 72) 192.168.33.15.22 > 192.168.33.1.36522: Flags [P.], cksum 0xc39b (incorrect -> 0xa84f), seq 2419:2451, ack 2626, win 19920, length 32 14:59:32.982347 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.1.36522 > 192.168.33.15.22: Flags [.], cksum 0x937f (correct), ack 2451, win 14600, length 0 14:59:32.982357 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 104) 192.168.33.1.36522 > 192.168.33.15.22: Flags [P.], seq 2626:2690, ack 2451, win 14600, length 64 14:59:32.982401 IP (tos 0x10, ttl 64, id 53791, offset 0, flags [DF], proto TCP (6), length 88) 192.168.33.15.22 > 192.168.33.1.36522: Flags [P.], seq 2451:2499, ack 2690, win 19920, length 48 14:59:32.982570 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.1.36522 > 192.168.33.15.22: Flags [.], cksum 0x930f (correct), ack 2499, win 14600, length 0 14:59:32.982702 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 104) 192.168.33.1.36522 > 192.168.33.15.22: Flags [P.], seq 2690:2754, ack 2499, win 14600, length 64 14:59:33.020066 IP (tos 0x10, ttl 64, id 53792, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.15.22 > 192.168.33.1.36522: Flags [.], cksum 0xc37b (incorrect -> 0x7e07), ack 2754, win 19920, length 0 14:59:33.983503 IP (tos 0x10, ttl 64, id 53793, offset 0, flags [DF], proto TCP (6), length 72) 192.168.33.15.22 > 192.168.33.1.36522: Flags [P.], cksum 0xc39b (incorrect -> 0x2aa7), seq 2499:2531, ack 2754, win 19920, length 32 14:59:33.983810 IP (tos 0x10, ttl 64, id 53794, offset 0, flags [DF], proto TCP (6), length 88) 192.168.33.15.22 > 192.168.33.1.36522: Flags [P.], seq 2531:2579, ack 2754, win 19920, length 48 14:59:33.984100 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.1.36522 > 192.168.33.15.22: Flags [.], cksum 0x92af (correct), ack 2531, win 14600, length 0 14:59:33.984139 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.1.36522 > 192.168.33.15.22: Flags [.], cksum 0x927f (correct), ack 2579, win 14600, length 0 14:59:34.022914 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 104) 192.168.33.1.36522 > 192.168.33.15.22: Flags [P.], seq 2754:2818, ack 2579, win 14600, length 64 14:59:34.022939 IP (tos 0x10, ttl 64, id 53795, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.15.22 > 192.168.33.1.36522: Flags [.], cksum 0xc37b (incorrect -> 0x7d77), ack 2818, win 19920, length 0 14:59:34.023554 IP (tos 0x10, ttl 64, id 53796, offset 0, flags [DF], proto TCP (6), length 88) 192.168.33.15.22 > 192.168.33.1.36522: Flags [P.], seq 2579:2627, ack 2818, win 19920, length 48 14:59:34.027571 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 40) 192.168.33.1.36522 > 192.168.33.15.22: Flags [.], cksum 0x920f (correct), ack 2627, win 14600, length 0 14:59:34.027603 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 4100) 192.168.33.1.36522 > 192.168.33.15.22: Flags [P.], seq 2818:6878, ack 2627, win 14600, length 4060

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