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• Fastest inline-assembly spinlock

  - by sigvardsen

  I'm writing a multithreaded application in c++, where performance is critical. I need to use a lot of locking while copying small structures between threads, for this I have chosen to use spinlocks. I have done some research and speed testing on this and I found that most implementations are roughly equally fast: Microsofts CRITICAL_SECTION, with SpinCount set to 1000, scores about 140 time units Implementing this algorithm with Microsofts InterlockedCompareExchange scores about 95 time units Ive also tried to use some inline assembly with __asm {} using something like this code and it scores about 70 time units, but I am not sure that a proper memory barrier has been created. Edit: The times given here are the time it takes for 2 threads to lock and unlock the spinlock 1,000,000 times. I know this isn't a lot of difference but as a spinlock is a heavily used object, one would think that programmers would have agreed on the fastest possible way to make a spinlock. Googling it leads to many different approaches however. I would think this aforementioned method would be the fastest if implemented using inline assembly and using the instruction CMPXCHG8B instead of comparing 32bit registers. Furthermore memory barriers must be taken into account, this could be done by LOCK CMPXHG8B (I think?), which guarantees "exclusive rights" to the shared memory between cores. At last [some suggests] that for busy waits should be accompanied by NOP:REP that would enable Hyper-threading processors to switch to another thread, but I am not sure whether this is true or not? From my performance-test of different spinlocks, it is seen that there is not much difference, but for purely academic purpose I would like to know which one is fastest. However as I have extremely limited experience in the assembly-language and with memory barriers, I would be happy if someone could write the assembly code for the last example I provided with LOCK CMPXCHG8B and proper memory barriers in the following template: __asm { spin_lock: ;locking code. spin_unlock: ;unlocking code. }

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• Polling servers at the same port - Threads and Java

  - by John

  Hi there. I'm currently busy working on an IP ban tool for the early versions of Call of Duty 1. (Apparently such a feature wasn't implemented in these versions). I've finished a single threaded application but it won't perform well enough for multiple servers, which is why I am trying to implement threading. Right now, each server has its own thread. I have a Networking class, which has a method; "GetStatus" -- this method is synchronized. This method uses a DatagramSocket to communicate with the server. Since this method is static and synchronized, I shouldn't get in trouble and receive a whole bunch of "Address already in use" exceptions. However, I have a second method named "SendMessage". This method is supposed to send a message to the server. How can I make sure "SendMessage" cannot be invoked when there's already a thread running in "GetStatus", and the other way around? If I make both synchronized, I will still get in trouble if Thread A is opening a socket on Port 99999 and invoking "SendMessage" while Thread B is opening a socket on the same port and invoking "GetStatus"? (Game servers are usually hosted on the same ports) I guess what I am really after is a way to make an entire class synchronized, so that only one method can be invoked and run at a time by a single thread. Hope that what I am trying to accomplish/avoid is made clear in this text. Any help is greatly appreciated.

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• What database is a good progression from MS Access for Coldfusion?

  - by Saul

  All my (home) CF learning has so far been done using Access as a database, and as far as the DB goes I "get it". There's no database server, and no need to log on to the database or anything, and setting up table relationships is easy and visual. Oh and its essentially free to deploy. However, I'm now working on an application that's likely to be used across several businesses and probably up to 50 concurrent users. I've heard that Access really isn't up to multi user use or production use on an app. What would you recommend as more suitable, preferably easy to grasp, with minimal tweeking needed for my SQL (I used a tool to convert to MySQL and it certainly handles concatenation differently, I dont want to have to do too much debugging), visual interface available, scalable, backupable, and whatever else I need that I don't yet know I need!

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• Smartest way to import massive datasets into a Rails application?

  - by williamjones

  I've got multiple massive (multi gigabyte) datasets I need to import into a Rails app. The datasets are currently each in their own database on my development machine, and I need to read from them and create rows in tables in my Rails database based on the information they contain. The tables in my Rails database will not be exactly the same as the tables in the source databases. What's the smartest way to go about this? I was thinking migrations, but I'm not exactly sure how to connect the migration to the databases, and even if that is possible, is that going to be ridiculously slow?

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• How to find Tomcat's PID and kill it in python?

  - by 4herpsand7derpsago

  Normally, one shuts down Apache Tomcat by running its shutdown.sh script (or batch file). In some cases, such as when Tomcat's web container is hosting a web app that does some crazy things with multi-threading, running shutdown.sh gracefully shuts down some parts of Tomcat (as I can see more available memory returning to the system), but the Tomcat process keeps running. I'm trying to write a simple Python script that: Calls shutdown.sh Runs ps -aef | grep tomcat to find any process with Tomcat referenced If applicable, kills the process with kill -9 <PID> Here's what I've got so far (as a prototype - I'm brand new to Python BTW): #!/usr/bin/python # Imports import sys import subprocess # Load from imported module. if __init__ == "__main__": main() # Main entry point. def main(): # Shutdown Tomcat shutdownCmd = "sh ${TOMCAT_HOME}/bin/shutdown.sh" subprocess.call([shutdownCmd], shell=true) # Check for PID grepCmd = "ps -aef | grep tomcat" grepResults = subprocess.call([grepCmd], shell=true) if(grepResult.length > 1): # Get PID and kill it. pid = ??? killPidCmd = "kill -9 $pid" subprocess.call([killPidCmd], shell=true) # Exit. sys.exit() I'm struggling with the middle part - with obtaining the grep results, checking to see if their size is greater than 1 (since grep always returns a reference to itself, at least 1 result will always be returned, methinks), and then parsing that returned PID and passing it into the killPidCmd. Thanks in advance!

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• tomcat multithreading problem

  - by jutky

  Hi all I'm writing a java application that runs in Tomcat, on a multi-core hardware. The application executes an algorithm and returns the answer to the user. The problem is that even when I run two requests simultaneously, the tomcat process uses at most one CPU core. As far as I understand each request in Tomcat is executed in separate thread, and JVM should run each thread on separate CPU core. What could be the problem that bounds the JVM or Tomcat to use no more than one core? Thanks in advance.

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• What would be a good "CMS" for me to use?

  - by Tim Geerts

  Hey, I'm looking for some sort of CMS system to implement here in terms of "documentation" system. Now, I'm not to sure about which system(s) would suit my needs best, so I thought I'd come here and type up my requirements so you could help me in narrowing down all the different options. One important note to make is that I'm not looking at a system where I can store certain documents (word, pdf, whatever). Rather at a system where I can type the "documentation"-text in some sort of post (like a blog). Requirements: - Multilanguage support - Tagging - Decent search support (tags, groupings, categories) - Version-control of posts/articles - Possibility of exporting post(s) to a pdf file - Support for multi-user (usergroup X can only see those posts, usergroup Y can see others, etc...) I know, these are some strange requirements if they're all combined, and I reckon most of you would perhaps say that I'd have to develop something like this inhouse rather then finding a descent working product out there (open source if possible). None the less, I thought I'd at least ask the opinion of y'all. Regards, Tim

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• Should I thread this?

  - by Psytronic

  I've got a "Loading Progress" WPF form which I instantiate when I start loading some results into my Main Window, and every time a result is loaded I want the progress bar to fill up by x amount (Based on the amount of results I'm loading). However what happens is that the Progress bar in the window stays blank the entire time, until the results have finished loading, then it will just display the full progress bar. Does this need threading to work properly? Or is it just to do with the way I'm trying to get it to work? //code snippet LoadingProgress lp = new LoadingProgress(feedCount); lp.Show(); foreach (FeedConfigGroup feed in _Feeds) { feed.insertFeeds(lp); } //part of insertFeeds(LoadingProgress lbBox) foreach (Feeds fd in _FeedSource) { lpBox.setText(fd.getName); XmlDocument feedResults = new XmlDocument(); feedResults.PreserveWhitespace = false; try { feedResults.Load(wc.OpenRead(fd.getURL)); } catch (WebException) { lpBox.addError(fd.getName); } foreach (XmlNode item in feedResults.SelectNodes("/rss/channel/item")) { //code for processing the nodes... } lpBox.progressIncrease(); } If more code is needed let me know.

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• How can we get unique elements from any ORDER BY DECREASING OR INCREASING

  - by Mohit

  Code given below is taken from the stackoverflow.com !!! Can anyone tell me how to get the array elements order by decreaseing or increasing !! plz help me !!! Thanks in advance $contents = file_get_contents($htmlurl); // Get rid of style, script etc $search = array('@<script[^>]*?>.*?</script>@si', // Strip out javascript '@<head>.*?</head>@siU', // Lose the head section '@<style[^>]*?>.*?</style>@siU', // Strip style tags properly '@<![\s\S]*?--[ \t\n\r]*>@' // Strip multi-line comments including CDATA ); $contents = preg_replace($search, '', $contents); $result = array_count_values( str_word_count( strip_tags($contents), 1 ) ); print_r($result);

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• How should my team decide between 3-tier and 2-tier architectures?

  - by j0rd4n

  My team is discussing the future direction we take our projects. Half the team believes in a pure 3-tier architecture while the other half favors a 2-tier architecture. Project Assumptions: Enterprise business applications Business logic needed between user and database Data validation necessary Service-oriented (prefer RESTful services) Multi-year maintenance plan Support hundreds of users 3-tier Team Favors: Persistant layer <== Domain layer <== UI layer Service boundary between at least persistant layer and domain layer. Domain layer might have service boundary between it. Translations between each layer (clean DTO separation) Hand roll persistance unless we can find creative yet elegant automation 2-tier Team Favors: Entity Framework + WCF Data Service layer <== UI layer Business logic kept in WCF Data Service interceptors Minimal translation between layers - favor faster coding So that's the high-level argument. What considerations should we take into account? What experiences have you had with either approach?

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• StructureMap: Calling repository constructor based on RouteData

  - by FreshCode

  I'm implementing a multi-tenant ASP.NET MVC application and using StructureMap for DI where my repositories depend on an ITenantContext interface, which depends on RouteData (or a base controller property). How do I tell StructureMap to construct TenantContext(tenantID); where tenantID is derived from my RouteData or some base controller property? Given the following route: {tenant}/{controller}/{action} My base controller retrieves and stores the correct Tenant based on the {tenant} URL parameter. Using Tenant, a repository with an ITenantContext can be constructed to retrieve only data that is relevant to that tenant. Based on the other DI questions, AbstractFactory could be a solution?solution?

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• What's the best way to return a random line in a text file using C?

  - by jeremy Ruten

  What's the best way to return a random line in a text file using C? It has to use the standard I/O library (<stdio.h>) because it's for Nintendo DS homebrew. Clarifications: Using a header in the file to store the number of lines won't work for what I want to do. I want it to be as random as possible (the best being if each line has an equal probability of being chosen as every other line.) The file will never change while the program is being run. (It's the DS, so no multi-tasking.)

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• Unresponsive UI when using BeginInvoke

  - by Kazoom

  Bckground I have a networked application written in C#. my server program has a UI and several communication threads, that read from tcp sockets and display messages on controller UI. Communication with each client is done through a seprate thread. When i recieve some stream of messages from one client , the thread for that client writes on UI, which is a richtextbox on a Form. I call SetTextHelper(string text) method of the form. which looks like this private delegate void MyTextUpdateHandler(string text); public void SetTextHelper(string text) { BeginInvoke(new MyTextUpdateHandler(SetText), new object[] { text }); } public setText(string text) { richtext.Text= text; } Question - If i use BeginInvoke my UI is entirely unresponsive when i m writing large stream of data to UI - Invoke solves that problem, but i read that for multi threaded environment where many thereads are sharing same resource Invoke can lead to deadlocks I share the common ichtextbox between around 16 threads - What would be a good desing for my situation?

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• New/strange Java "try()" syntax?

  - by Ali

  While messing around with the custom formatting options in Eclipse, in one of the sample pieces of code, I say code as follows: /** * 'try-with-resources' */ class Example { void foo() { try (FileReader reader1 = new FileReader("file1"); FileReader reader2 = new FileReader("file2")) { } } } I've never seen try used like this and I've been coding in Java for 9 years! Does any one know why you would do this? What is a possible use-case / benefit of doing this? An other pieces of code I saw, I thought was a very useful shorthand so I'm sharing it here as well, it's pretty obvious what it does: /** * 'multi-catch' */ class Example { void foo() { try { } catch (IllegalArgumentException | NullPointerException | ClassCastException e) { e.printStackTrace(); } } }

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• Apply dynamic list of templates to an argument

  - by Diego Martinez

  I need apply a variable sequence of templates to an argument. example 1: arg:tpl1():tpl2():...:tplN() Suppose that i have other multi valued argument, and each value is the name for a dynamic template invocation. ¿What is the better form of apply all the templates from the list to my argument? tplNames : {name | <(name)(arg)>} not works, just apply a template ever to the same innitial value of my argument, i need the same result of example 1 but in a dynamic way. Thank you!!

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• Filp route value in asp.net mvc routes

  - by Herman

  Hi all, I am new to asp.net mvc, so please bear with me. We have the following route dictionary setup. routes.MapRoute( "Default", // Route name "{language}/{controller}/{action}/{id}", // URL with parameters new { language = "en", controller = "Home", action = "Index", id = "" } // Parameter defaults ); for any given page in our app, we to render a link to the a french version of the same page. For example, the page: http://www.example.com/en/home should have link on that page that points to http://www.example.com/fr/home Now I have the following UrlHelper extension method public static string FilpLanguage(this UrlHelper urlHelper) { var data = urlHelper.RequestContext.RouteData; if (System.Threading.Thread.CurrentThread.CurrentCulture == CultureInfo.GetCultureInfoByIetfLanguageTag("en-CA")) data.Values["language"] = "fr"; else data.Values["language"] = "en"; return urlHelper.RouteUrl(data.Values.Where(item => item.Value != null)); } However, calling FilpLanguage on www.example.com/en/home will return the following URL: www.example.com/en/home?current=[,] Am I missing something here? where did the current parameter come from? Thanks in advance.

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• How do I wait for a C# event to be raised?

  - by Evan Barkley

  I have a Sender class that sends a Message on a IChannel: public class MessageEventArgs : EventArgs { public Message Message { get; private set; } public MessageEventArgs(Message m) { Message = m; } } public interface IChannel { public event EventHandler<MessageEventArgs> MessageReceived; void Send(Message m); } public class Sender { public const int MaxWaitInMs = 5000; private IChannel _c = ...; public Message Send(Message m) { _c.Send(m); // wait for MaxWaitInMs to get an event from _c.MessageReceived // return the message or null if no message was received in response } } When we send messages, the IChannel sometimes gives a response depending on what kind of Message was sent by raising the MessageReceived event. The event arguments contain the message of interest. I want Sender.Send() method to wait for a short time to see if this event is raised. If so, I'll return its MessageEventArgs.Message property. If not, I return a null Message. How can I wait in this way? I'd prefer not to have do the threading legwork with ManualResetEvents and such, so sticking to regular events would be optimal for me.

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• Why hasn't functional programming taken over yet?

  - by pankrax

  I've read some texts about declarative/functional programming (languages), tried out Haskell as well as written one myself. From what I've seen, functional programming has several advantages over the classical imperative style: Stateless programs; No side effects Concurrency; Plays extremely nice with the rising multi-core technology Programs are usually shorter and in some cases easier to read Productivity goes up (example: Erlang) Imperative programming is a very old paradigm (as far as I know) and possibly not suitable for the 21st century Why are companies using or programs written in functional languages still so "rare"? Why, when looking at the advantages of functional programming, are we still using imperative programming languages? Maybe it was too early for it in 1990, but today?

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• How to get site context/information during the PreapplicationStartMethod

  - by Mike

  When you run the same web based application as a multi-tenant application for different clients is there a way during the PreapplicationStartMethod to gain some kind of context to the site that is being started? More specifically I'd like to get the host header information (the "bindingInformation" attribute value from the applicationHost.config); I have found ways to get this information at the time of a specific request long after the application has started. Is there a way to get the information during the application startup process? This is an MVC 3 application and IIS 7.5.

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• how to add multiview in a radio button

  - by Naveen31

  protected void ddlto_SelectedIndexChanged(object sender, EventArgs e) { } protected void RadioButton1_CheckedChanged1(object sender, EventArgs e) { MultiView1.ActiveViewIndex = 0; } protected void RadioButton2_CheckedChanged(object sender, EventArgs e) { MultiView1.ActiveViewIndex = 2; } <asp:RadioButtonList ID="RadioButtonList2" runat="server" AutoPostBack="True" RepeatDirection="Horizontal" Font-Names="Arial" Font-Size="Small" onselectedindexchanged="MultiView1_ActiveViewChanged"> <asp:ListItem Selected="True">One Way</asp:ListItem> <asp:ListItem>Round Trip</asp:ListItem> <asp:ListItem>Multi City</asp:ListItem> </asp:RadioButtonList> i have a radiolist of thre buttons-one way,round trip and multicity, i have taken a multiview in which in view 2 i have added the codes codes,and i want to show that code when i click on the 2nd radio button i.e on round trip,how to do it. plzz help

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• What's the fastest way to scrape a lot of pages in php?

  - by Yegor

  I have a data aggregator that relies on scraping several sites, and indexing their information in a way that is searchable to the user. I need to be able to scrape a vast number of pages, daily, and I have ran into problems using simple curl requests, that are fairly slow when executed in rapid sequence for a long time (the scraper runs 24/7 basically). Running a multi curl request in a simple while loop is fairly slow. I speeded it up by doing individual curl requests in a background process, which works faster, but sooner or later the slower requests start piling up, which ends up crashing the server. Are there more efficient ways of scraping data? perhaps command line curl?

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• .NET Multipage Tiff with Lossy Compression

  - by Adam Berent

  I need a way to take several jpgs and convert them into a single multi page Tiff. I have that working using GDI+ however it only works with the compression LZW which is lossless. This means that my 3 50KB Jpgs turn into 3MB multipage Tiff file. This is not something I can accept for the software that I am working on. I know that Tiff Image format can use a JPG compression scheme but GDI+ does not seem to support this. If anyone knows how to do this in .NET (C#) or of any component that does this conversion.

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• With Maven2, how would I specify a custom directory to which a dependency should be copied?

  - by Benny

  Basically, I have a multi-module project consisting of 5 different modules. One of the modules is kind of the parent module to the other 4, meaning the other 4 need to be built before the 5th, so you could say that each of the 4 modules is a dependency of the 5th. Thus, I've made dependency entries for each of the modules in the 5th module's pom.xml. However, when I build the project, I don't want those 4 dependencies copied to the "lib" directory of the 5th module. I'd like to specify the directory into which each of them should be placed explicitly. Is there any way to do this with Maven2? Thanks for your help, B.J.

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• Passing variables from a thread to another form using C#

  - by kirstom14

  Hi, I am trying to pass 2 variables from a thread, in the MainForm, to another form, but when doing so an error occurs. private void TrackingThread( ) { float targetX = 0; float targetY = 0; while ( true ) { camera1Acquired.WaitOne( ); camera2Acquired.WaitOne( ); lock ( this ) { // stop the thread if it was signaled if ( ( x1 == -1 ) && ( y1 == -1 ) && ( x2 == -1 ) && ( y2 == -1 ) ) { break; } // get middle point targetX = ( x1 + x2 ) / 2; targetY = ( y1 + y2 ) / 2; } if (directionForm != null) { directionForm.RunMotors(targetX, targetY); } } } In the form, directionForm, I am simply displaying the variables targetX and targetY. The code for the directionForm.RunMotors() is the following: public void RunMotors(float x, float y) { label1.Text = "X-ordinate " + x.ToString(); label2.Text = "Y-ordinate " + y.ToString(); } The error happen when I am trying to display the two variables: "InvalidOperationException was unhandled Cross-threading operation not valid: Control label1 accessed from a thread other than . the thread it was created on" What shall I do??? Thanks in advance

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• How to send mail with large size attachment using System.Net.Mail to Google Apps ?

  - by Preeti

  Hi, I am trying to send mail with large size attachment upto (1MB,2MB). But sending mail fails.(Sending to Google Apps) as: MailItemEntry[] entries = new MailItemEntry[1]; String EmlPath = "C:\\testemail.eml"; String msg = File.ReadAllText(EmlPath); entries[0] = new MailItemEntry(); entries[0].Rfc822Msg = new Rfc822MsgElement(msg); How can i divide attachments into multi part? Exception I am getting while migrating this EML to Google apps is: {"The request was aborted: The request was canceled."}

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