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  • Sleep Function Error In C

    - by Arman
    I have a file of data Dump, in with different timestamped data available, I get the time from timestamp and sleep my c thread for that time. But the problem is that The actual time difference is 10 second and the data which I receive at the receiving end is almost 14, 15 second delay. I am using window OS. Kindly guide me. Sorry for my week English.

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  • Erlang rb module

    - by Justin
    When looking up messages in a sasl log using rb:list() or rb:show(), rb seems to dump the output in the console and return 'ok'; is there any way to configure rb to get it to return the actual log message ? Thanks

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  • recursion resulting in extra unwanted data

    - by spacerace
    I'm writing a module to handle dice rolling. Given x die of y sides, I'm trying to come up with a list of all potential roll combinations. This code assumes 3 die, each with 3 sides labeled 1, 2, and 3. (I realize I'm using "magic numbers" but this is just an attempt to simplify and get the base code working.) int[] set = { 1, 1, 1 }; list = diceroll.recurse(0,0, list, set); ... public ArrayList<Integer> recurse(int index, int i, ArrayList<Integer> list, int[] set){ if(index < 3){ // System.out.print("\n(looping on "+index+")\n"); for(int k=1;k<=3;k++){ // System.out.print("setting i"+index+" to "+k+" "); set[index] = k; dump(set); recurse(index+1, i, list, set); } } return list; } (dump() is a simple method to just display the contents of list[]. The variable i is not used at the moment.) What I'm attempting to do is increment a list[index] by one, stepping through the entire length of the list and incrementing as I go. This is my "best attempt" code. Here is the output: Bold output is what I'm looking for. I can't figure out how to get rid of the rest. (This is assuming three dice, each with 3 sides. Using recursion so I can scale it up to any x dice with y sides.) [1][1][1] [1][1][1] [1][1][1] [1][1][2] [1][1][3] [1][2][3] [1][2][1] [1][2][2] [1][2][3] [1][3][3] [1][3][1] [1][3][2] [1][3][3] [2][3][3] [2][1][3] [2][1][1] [2][1][2] [2][1][3] [2][2][3] [2][2][1] [2][2][2] [2][2][3] [2][3][3] [2][3][1] [2][3][2] [2][3][3] [3][3][3] [3][1][3] [3][1][1] [3][1][2] [3][1][3] [3][2][3] [3][2][1] [3][2][2] [3][2][3] [3][3][3] [3][3][1] [3][3][2] [3][3][3] I apologize for the formatting, best I could come up with. Any help would be greatly appreciated. (This method was actually stemmed to use the data for something quite trivial, but has turned into a personal challenge. :) edit: If there is another approach to solving this problem I'd be all ears, but I'd also like to solve my current problem and successfully use recursion for something useful.

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  • How to tell Ruby not to serialize an attribute or how to overload marshal_dump properly?

    - by GregMoreno
    I have an attribute in my AR:B that is not serializeable. o = Discussion.find(6) Marshal.dump(o) TypeError: no marshal_dump is defined for class Proc from (irb):10:in `dump' I know the culprit and what I want is to set this variable to nil before any serialization takes place. I can do this but I'm stuck with the proper way to override marshal_dump def marshal_dump @problem = nil # what is the right return here? end Or is there is way to tell Ruby or AR not to serialize an object?

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  • "Blank SQL" error with phppgadmin

    - by Hoàng Long
    Here is my problem: I export a database A_DB using "export" function of Phppgadmin. The dump file A_dump.sql includes both the database structure and data. Then I try to create another blank database B_DB, and import A_dump.sql into it. Every time I do that, the transaction failed with no error reported: SQL error: In statement: Is there some logs that I can find in phppgadmin that would allow me to investigate this problem? I have tried searching for an hour, but still not find anything.

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  • Printing values of all fields in C++ structure

    - by Zhinkaas
    Say a simple structure struct abc { int a; char b; } I got some value in a variable defined as its structure and now I want to print below a = [some value] b = [some character] What is the best way to achieve this for an arbitrary structure without having to write a dump...(...) function for each of the structure I encounter?

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  • Using Oracle Zero Date

    - by Noam
    I have an application with existing data, that has Zero in the date column. When I look at it from sqlplus I see: 00-DECEMB when I use the dump function on this column, I Get: Typ=12 Len=7: 100,100,0,0,1,1,1 I need to work with the existing data from .Net (no changes to the data,or the data structure or even existing sql statements) How the hack do I read this value, or write it. The db version varies, from 8 to 11. Help would be appreciated

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  • Access Voilation in std::pair

    - by sameer karjatkar
    I have an application which is trying to populate a pair . Out of no where the application crashes . The Windbg analysis on the crash dump suggest PRIMARY_PROBLEM_CLASS: INVALID_POINTER_READ DEFAULT_BUCKET_ID: INVALID_POINTER_READ STACK_TEXT: 0389f1dc EPFilter32!std::vector,std::allocator ::size+0xc INVALID_POINTER_READ_c0000005_Test.DLL!std::vector_std::pair_unsigned_int, unsigned_int_,std::allocator_std::pair_unsigned_int,unsigned_int___::size Following is the statement in the code where it fails const branch_info& b1 = en1.m_branches[i1]; where branch_info is std::pair and the en1.m_branches[i1] fetches me a pair value

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  • Python to extract data from a file

    - by user297003
    Hi, I am new to python. I am trying to extract the text between that has specific text file: ---- data1 data1 data1 extractme ---- data2 data2 data2 ---- data3 data3 extractme ---- and then dump it to text file so that ---- data1 data1 data1 extractme --- data3 data3 extractme --- Thanks for the help.

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  • Working with Content Shell on windows 7

    - by JAre
    I can't run Content Shell on my system (Windows 7 x64): When i run --dump-render-tree with the stable release content_shell.exe crashes with message: [XXXX:XXXX:0522/XXXXXX:XXXXXXXXX:FATAL:content_main_runner.cc(735)] Check failed: base::i18n::InitializeICU() were X - some number. And i can't run dev build because it misses mojo_system.dll. Is there any way to fix it? Does it work on Linux or MacOS? If so i probably can run it in VM For the time being.

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  • I got the address of a large managed object in WinDbg, what next?

    - by Mahen
    I created a high memory utilization dump and using !dumpheap -stat and !dumpheap -mt I got the address of two large string generic list of 30 MB each. I want to know more about these lists. What they contain or which piece of code is using them. Is there a way to find them out? 0:000 !do 2b370038 Name: System.Object[] MethodTable: 71e240bc EEClass: 71c0da54 Size: 33554448(0x2000010) bytes Array: Rank 1, Number of elements 8388608, Type CLASS Element Type: System.Collections.Generic.List`1[[System.String, mscorlib]] Fields: None

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  • MySQL charset issue.

    - by Shagymoe
    I'm not sure exactly why this happened, but I'm assuming it was an dump and import. The db is full of characters like — for commas and such. I've tried various solutions on the web, but nothing seems to work. I've verified that the html header specifies utf8. Any ideas on how I can get the entire db back to normal characters?

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  • How can I extract a range of lines from a text file on unix?

    - by Adam J. Forster
    I have a ~23000 line sql dump containing several databases worth of data. I need to extract a certain section of this file (i.e. the data for a single database) and place it in a new file. I know both the start and end line numbers of the data that I want. Does anyone know a unix command (or series of commands) to extract all lines from a file between say line 16224 and 16482 and then redirect them into a new file?

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  • C++ question on file formats and od

    - by user231536
    I have the following simple code: ofstream output("test"); output << 'a'; When I do an octal dump of the file, I get this: 0000000 000141 0000001 I can see that 000141 (in base 8) is 8 bits wide and 0000001 is probably EOF. What is the first byte of all 0's and why is it there? I know it is null is ascii but what is its purpose?

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  • Loading SQLite Database into Android App

    - by Chris
    I am able to create, write and read an SQLite Database in my Android App. I have a copy of the Database that is fully populated with data, and I want to get that data into the App's Database. Is it possible to access my pouplaed database from inside my App? Or can I at least create a copy of the populated database and then use that copy? Or do I need to do a .dump and put all the inserts into the Android code?

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  • Registration form validation not validating

    - by jgray
    I am a noob when it comes to web development. I am trying to validate a registration form and to me it looks right but it will not validate.. This is what i have so far and i am validating through a repository or database. Any help would be greatly appreciated. thanks <?php session_start(); $title = "User Registration"; $keywords = "Name, contact, phone, e-mail, registration"; $description = "user registration becoming a member."; require "partials/_html_header.php"; //require "partials/_header.php"; require "partials/_menu.php"; require "DataRepository.php"; // if all validation passed save user $db = new DataRepository(); // form validation goes here $first_nameErr = $emailErr = $passwordErr = $passwordConfirmErr = ""; $first_name = $last_name = $email = $password = $passwordConfirm = ""; if(isset($_POST['submit'])) { $valid = TRUE; // check if all fields are valid { if ($_SERVER["REQUEST_METHOD"] == "POST") { if (empty($_POST["first_name"])) {$first_nameErr = "Name is required";} else { // $first_name = test_input($_POST["first_name"]); // check if name only contains letters and whitespace if (!preg_match("/^[a-zA-Z ]*$/",$first_name)) { $first_nameErr = "Only letters and white space allowed"; } } if (empty($_POST["email"])) {$emailErr = "Email is required";} else { // $email = test_input($_POST["email"]); // check if e-mail address syntax is valid if (!preg_match("/([\w\-]+\@[\w\-]+\.[\w\-]+)/",$email)) { $emailErr = "Invalid email format"; } } if (!preg_match("/(......)/",$password)) { $passwordErr = "Subject must contain THREE or more characters!"; } if ($_POST['password']!= $_POST['passwordConfirm']) { echo("Oops! Password did not match! Try again. "); } function test_input($data) { $data = trim($data); $data = stripslashes($data); $data = htmlspecialchars($data); return $data; } } } if(!$db->isEmailUnique($_POST['email'])) { $valid = FALSE; //display errors in the correct places } // if still valid save the user if($valid) { $new_user = array( 'first_name' => $_POST['first_name'], 'last_name' => $_POST['last_name'], 'email' => $_POST['email'], 'password' => $_POST['password'] ); $results = $db->saveUser($new_user); if($results == TRUE) { header("Location: login.php"); } else { echo "WTF!"; exit; } } } ?> <head> <style> .error {color: #FF0000;} </style> </head> <h1 class="center"> World Wide Web Creations' User Registration </h1> <p><span class="error"></span><p> <form method="POST" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>" onsubmit="return validate_form()" > First Name: <input type="text" name="first_name" id="first_name" value="<?php echo $first_name;?>" /> <span class="error"> <?php echo $first_nameErr;?></span> <br /> <br /> Last Name(Optional): <input type="text" name="last_name" id="last_name" value="<?php echo $last_name;?>" /> <br /> <br /> E-mail: <input type="email" name="email" id="email" value="<?php echo $email;?>" /> <span class="error"> <?php echo $emailErr;?></span> <br /> <br /> Password: <input type="password" name="password" id="password" value="" /> <span class="error"> <?php echo $passwordErr;?></span> <br /> <br /> Confirmation Password: <input type="password" name="passwordConfirm" id="passwordConfirm" value="" /> <span class="error"> <?php echo $passwordConfirmErr;?></span> <br /> <br /> <br /> <br /> <input type="submit" name="submit" id="submit" value="Submit Data" /> <input type="reset" name="reset" id="reset" value="Reset Form" /> </form> </body> </html> <?php require "partials/_footer.php"; require "partials/_html_footer.php"; ?> class DataRepository { // version number private $version = "1.0.3"; // turn on and off debugging private static $debug = FALSE; // flag to (re)initialize db on each call private static $initialize_db = FALSE; // insert test data on initialization private static $load_default_data = TRUE; const DATAFILE = "203data.txt"; private $data = NULL; private $errors = array(); private $user_fields = array( 'id' => array('required' => 0), 'created_at' => array('required' => 0), 'updated_at' => array('required' => 0), 'first_name' => array('required' => 1), 'last_name' => array('required' => 0), 'email' => array('required' => 1), 'password' => array('required' => 1), 'level' => array('required' => 0, 'default' => 2), ); private $post_fields = array( 'id' => array('required' => 0), 'created_at' => array('required' => 0), 'updated_at' => array('required' => 0), 'user_id' => array('required' => 1), 'title' => array('required' => 1), 'message' => array('required' => 1), 'private' => array('required' => 0, 'default' => 0), ); private $default_user = array( 'id' => 1, 'created_at' => '2013-01-01 00:00:00', 'updated_at' => '2013-01-01 00:00:00', 'first_name' => 'Admin Joe', 'last_name' => 'Tester', 'email' => '[email protected]', 'password' => 'a94a8fe5ccb19ba61c4c0873d391e987982fbbd3', 'level' => 1, ); private $default_post = array( 'id' => 1, 'created_at' => '2013-01-01 00:00:00', 'updated_at' => '2013-01-01 00:00:00', 'user_id' => 1, 'title' => 'My First Post', 'message' => 'This is the message of the first post.', 'private' => 0, ); // constructor will load existing data into memory // if it does not exist it will create it and initialize if desired public function __construct() { // check if need to reset if(DataRepository::$initialize_db AND file_exists(DataRepository::DATAFILE)) { unlink(DataRepository::DATAFILE); } // if file doesn't exist, create the initial datafile if(!file_exists(DataRepository::DATAFILE)) { $this->log("Data file does not exist. Attempting to create it... (".__FUNCTION__.":".__LINE__.")"); // create initial file $this->data = array( 'users' => array( ), 'posts' => array() ); // load default data if needed if(DataRepository::$load_default_data) { $this->data['users'][1] = $this->default_user; $this->data['posts'][1] = $this->default_post; } $this->writeTheData(); } // load the data into memory for use $this->loadTheData(); } private function showErrors($break = TRUE, $type = NULL) { if(count($this->errors) > 0) { echo "<div style=\"color:red;font-weight: bold;font-size: 1.3em\":<h3>$type Errors</h3><ol>"; foreach($this->errors AS $error) { echo "<li>$error</li>"; } echo "</ol></div>"; if($break) { "</br></br></br>Exiting because of errors!"; exit; } } } private function writeTheData() { $this->log("Attempting to write the datafile: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); file_put_contents(DataRepository::DATAFILE, json_encode($this->data)); $this->log("Datafile written: ".DataRepository::DATAFILE." (line: ".__LINE__.")"); } private function loadTheData() { $this->log("Attempting to load the datafile: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); $this->data = json_decode(file_get_contents(DataRepository::DATAFILE), true); $this->log("Datafile loaded: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")", $this->data); } private function validateFields(&$info, $fields, $pre_errors = NULL) { // merge in any pre_errors if($pre_errors != NULL) { $this->errors = array_merge($this->errors, $pre_errors); } // check all required fields foreach($fields AS $field => $reqs) { if(isset($reqs['required']) AND $reqs['required'] == 1) { if(!isset($info[$field]) OR strlen($info[$field]) == 0) { $this->errors[] = "$field is a REQUIRED field"; } } // set any default values if not present if(isset($reqs['default']) AND (!isset($info[$field]) OR $info[$field] == "")) { $info[$field] = $reqs['default']; } } $this->showErrors(); if(count($this->errors) == 0) { return TRUE; } else { return FALSE; } } private function validateUser(&$user_info) { // check if the email is already in use $this->log("About to check pre_errors: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")", $user_info); $pre_errors = NULL; if(isset($user_info['email'])) { if(!$this->isEmailUnique($user_info['email'])) { $pre_errors = array('The email: '.$user_info['email'].' is already used in our system'); } } $this->log("After pre_error check: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")", $pre_errors); return $this->validateFields($user_info, $this->user_fields, $pre_errors); } private function validatePost(&$post_info) { // check if the user_id in the post actually exists $this->log("About to check pre_errors: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")", $post_info); $pre_errors = NULL; if(isset($post_info['user_id'])) { if(!isset($this->data['users'][$post_info['user_id']])) { $pre_errors = array('The posts must belong to a valid user. (User '.$post_info['user_id'].' does not exist in the data'); } } $this->log("After pre_error check: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")", $pre_errors); return $this->validateFields($post_info, $this->post_fields, $pre_errors); } private function log($message, $data = NULL) { $style = "background-color: #F8F8F8; border: 1px solid #DDDDDD; border-radius: 3px; font-size: 13px; line-height: 19px; overflow: auto; padding: 6px 10px;"; if(DataRepository::$debug) { if($data != NULL) { $dump = "<div style=\"$style\"><pre>".json_encode($data, JSON_PRETTY_PRINT)."</pre></div>"; } else { $dump = NULL; } echo "<code><b>Debug:</b> $message</code>$dump<br />"; } } public function saveUser($user_info) { $this->log("Entering saveUser: (".__FUNCTION__.":".__LINE__.")", $user_info); $mydata = array(); $update = FALSE; // check for existing data if(isset($user_info['id']) AND $this->data['users'][$user_info['id']]) { $mydata = $this->data['users'][$user_info['id']]; $this->log("Loaded prior user: ".print_r($mydata, TRUE)." (".__FUNCTION__.":".__LINE__.")"); } // copy over existing values $this->log("Before copying over existing values: (".__FUNCTION__.":".__LINE__.")", $mydata); foreach($user_info AS $k => $v) { $mydata[$k] = $user_info[$k]; } $this->log("After copying over existing values: (".__FUNCTION__.":".__LINE__.")", $mydata); // check required fields if($this->validateUser($mydata)) { // hash password if new if(isset($mydata['password'])) { $mydata['password'] = sha1($mydata['password']); } // if no id, add the next available one if(!isset($mydata['id']) OR (int)$mydata['id'] < 1) { $this->log("No id set: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); if(count($this->data['users']) == 0) { $mydata['id'] = 1; $this->log("Setting id to 1: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); } else { $mydata['id'] = max(array_keys($this->data['users']))+1; $this->log("Found max id and added 1 [".$mydata['id']."]: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); } } // set created date if null if(!isset($mydata['created_at'])) { $mydata['created_at'] = date ("Y-m-d H:i:s", time()); } // update modified time $mydata['modified_at'] = date ("Y-m-d H:i:s", time()); // copy into data and save $this->log("Before data save: (".__FUNCTION__.":".__LINE__.")", $this->data); $this->data['users'][$mydata['id']] = $mydata; $this->writeTheData(); } return TRUE; } public function getUserById($id) { if(isset($this->data['users'][$id])) { return $this->data['users'][$id]; } else { return array(); } } public function isEmailUnique($email) { // find the user that has the right username/password foreach($this->data['users'] AS $k => $v) { $this->log("Checking unique email: {$v['email']} == $email (".__FUNCTION__.":".__LINE__.")", NULL); if($v['email'] == $email) { $this->log("FOUND NOT unique email: {$v['email']} == $email (".__FUNCTION__.":".__LINE__.")", NULL); return FALSE; break; } } $this->log("Email IS unique: $email (".__FUNCTION__.":".__LINE__.")", NULL); return TRUE; } public function login($username, $password) { // hash password for validation $password = sha1($password); $this->log("Attempting to login with $username / $password: (".__FUNCTION__.":".__LINE__.")", NULL); $user = NULL; // find the user that has the right username/password foreach($this->data['users'] AS $k => $v) { if($v['email'] == $username AND $v['password'] == $password) { $user = $v; break; } } $this->log("Exiting login: (".__FUNCTION__.":".__LINE__.")", $user); return $user; } public function savePost($post_info) { $this->log("Entering savePost: (".__FUNCTION__.":".__LINE__.")", $post_info); $mydata = array(); // check for existing data if(isset($post_info['id']) AND $this->data['posts'][$post_info['id']]) { $mydata = $this->data['posts'][$post_info['id']]; $this->log("Loaded prior posts: ".print_r($mydata, TRUE)." (".__FUNCTION__.":".__LINE__.")"); } $this->log("Before copying over existing values: (".__FUNCTION__.":".__LINE__.")", $mydata); foreach($post_info AS $k => $v) { $mydata[$k] = $post_info[$k]; } $this->log("After copying over existing values: (".__FUNCTION__.":".__LINE__.")", $mydata); // check required fields if($this->validatePost($mydata)) { // if no id, add the next available one if(!isset($mydata['id']) OR (int)$mydata['id'] < 1) { $this->log("No id set: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); if(count($this->data['posts']) == 0) { $mydata['id'] = 1; $this->log("Setting id to 1: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); } else { $mydata['id'] = max(array_keys($this->data['posts']))+1; $this->log("Found max id and added 1 [".$mydata['id']."]: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); } } // set created date if null if(!isset($mydata['created_at'])) { $mydata['created_at'] = date ("Y-m-d H:i:s", time()); } // update modified time $mydata['modified_at'] = date ("Y-m-d H:i:s", time()); // copy into data and save $this->data['posts'][$mydata['id']] = $mydata; $this->log("Before data save: (".__FUNCTION__.":".__LINE__.")", $this->data); $this->writeTheData(); } return TRUE; } public function getAllPosts() { return $this->loadPostsUsers($this->data['posts']); } public function loadPostsUsers($posts) { foreach($posts AS $id => $post) { $posts[$id]['user'] = $this->getUserById($post['user_id']); } return $posts; } public function dump($line_number, $temp = 'NO') { // if(DataRepository::$debug) { if($temp == 'NO') { $temp = $this->data; } echo "<pre>Dumping from line: $line_number\n"; echo json_encode($temp, JSON_PRETTY_PRINT); echo "</pre>"; } } } /* * Change Log * * 1.0.0 * - first version * 1.0.1 * - Added isEmailUnique() function for form validation and precheck on user save * 1.0.2 * - Fixed getAllPosts() to include the post's user info * - Added loadPostsUsers() to load one or more posts with their user info * 1.0.3 * - Added autoload to always add admin Joe. */

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  • Most efficient way to move a few SQL Server tables to SQLite?

    - by wom
    I have a fairly large SQL Server database; I'd like to pull 4 tables out and dump them directly into an sqlite.db for remote querying (via nightly batch). I was about to write a script to step through(most likely on a unix host kicked off via cron); but there should be a simpler method to export the tables directly (SQLite not an option in the included DTS Import/Export wizard) What would the most efficient method of dumping the SQL Server tables to SQLite via batch be?

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  • Reading from a very large table using multiple threads (Java ) and writing them to a single file

    - by user2534926
    I am currently facing a situation where i have a table with almost 80 millions data and i have to take a dump of that table and store it into a csv file. Currently i am using a not so professional approach( with a perl script+DBI interface , printing the values to stdout and redirecting to a csv file). Now i am planning to use java threading approach. Can you suggest a way forward. Thanks in advance

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  • A Taxonomy of Numerical Methods v1

    - by JoshReuben
    Numerical Analysis – When, What, (but not how) Once you understand the Math & know C++, Numerical Methods are basically blocks of iterative & conditional math code. I found the real trick was seeing the forest for the trees – knowing which method to use for which situation. Its pretty easy to get lost in the details – so I’ve tried to organize these methods in a way that I can quickly look this up. I’ve included links to detailed explanations and to C++ code examples. I’ve tried to classify Numerical methods in the following broad categories: Solving Systems of Linear Equations Solving Non-Linear Equations Iteratively Interpolation Curve Fitting Optimization Numerical Differentiation & Integration Solving ODEs Boundary Problems Solving EigenValue problems Enjoy – I did ! Solving Systems of Linear Equations Overview Solve sets of algebraic equations with x unknowns The set is commonly in matrix form Gauss-Jordan Elimination http://en.wikipedia.org/wiki/Gauss%E2%80%93Jordan_elimination C++: http://www.codekeep.net/snippets/623f1923-e03c-4636-8c92-c9dc7aa0d3c0.aspx Produces solution of the equations & the coefficient matrix Efficient, stable 2 steps: · Forward Elimination – matrix decomposition: reduce set to triangular form (0s below the diagonal) or row echelon form. If degenerate, then there is no solution · Backward Elimination –write the original matrix as the product of ints inverse matrix & its reduced row-echelon matrix à reduce set to row canonical form & use back-substitution to find the solution to the set Elementary ops for matrix decomposition: · Row multiplication · Row switching · Add multiples of rows to other rows Use pivoting to ensure rows are ordered for achieving triangular form LU Decomposition http://en.wikipedia.org/wiki/LU_decomposition C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-lu-decomposition-for-solving.html Represent the matrix as a product of lower & upper triangular matrices A modified version of GJ Elimination Advantage – can easily apply forward & backward elimination to solve triangular matrices Techniques: · Doolittle Method – sets the L matrix diagonal to unity · Crout Method - sets the U matrix diagonal to unity Note: both the L & U matrices share the same unity diagonal & can be stored compactly in the same matrix Gauss-Seidel Iteration http://en.wikipedia.org/wiki/Gauss%E2%80%93Seidel_method C++: http://www.nr.com/forum/showthread.php?t=722 Transform the linear set of equations into a single equation & then use numerical integration (as integration formulas have Sums, it is implemented iteratively). an optimization of Gauss-Jacobi: 1.5 times faster, requires 0.25 iterations to achieve the same tolerance Solving Non-Linear Equations Iteratively find roots of polynomials – there may be 0, 1 or n solutions for an n order polynomial use iterative techniques Iterative methods · used when there are no known analytical techniques · Requires set functions to be continuous & differentiable · Requires an initial seed value – choice is critical to convergence à conduct multiple runs with different starting points & then select best result · Systematic - iterate until diminishing returns, tolerance or max iteration conditions are met · bracketing techniques will always yield convergent solutions, non-bracketing methods may fail to converge Incremental method if a nonlinear function has opposite signs at 2 ends of a small interval x1 & x2, then there is likely to be a solution in their interval – solutions are detected by evaluating a function over interval steps, for a change in sign, adjusting the step size dynamically. Limitations – can miss closely spaced solutions in large intervals, cannot detect degenerate (coinciding) solutions, limited to functions that cross the x-axis, gives false positives for singularities Fixed point method http://en.wikipedia.org/wiki/Fixed-point_iteration C++: http://books.google.co.il/books?id=weYj75E_t6MC&pg=PA79&lpg=PA79&dq=fixed+point+method++c%2B%2B&source=bl&ots=LQ-5P_taoC&sig=lENUUIYBK53tZtTwNfHLy5PEWDk&hl=en&sa=X&ei=wezDUPW1J5DptQaMsIHQCw&redir_esc=y#v=onepage&q=fixed%20point%20method%20%20c%2B%2B&f=false Algebraically rearrange a solution to isolate a variable then apply incremental method Bisection method http://en.wikipedia.org/wiki/Bisection_method C++: http://numericalcomputing.wordpress.com/category/algorithms/ Bracketed - Select an initial interval, keep bisecting it ad midpoint into sub-intervals and then apply incremental method on smaller & smaller intervals – zoom in Adv: unaffected by function gradient à reliable Disadv: slow convergence False Position Method http://en.wikipedia.org/wiki/False_position_method C++: http://www.dreamincode.net/forums/topic/126100-bisection-and-false-position-methods/ Bracketed - Select an initial interval , & use the relative value of function at interval end points to select next sub-intervals (estimate how far between the end points the solution might be & subdivide based on this) Newton-Raphson method http://en.wikipedia.org/wiki/Newton's_method C++: http://www-users.cselabs.umn.edu/classes/Summer-2012/csci1113/index.php?page=./newt3 Also known as Newton's method Convenient, efficient Not bracketed – only a single initial guess is required to start iteration – requires an analytical expression for the first derivative of the function as input. Evaluates the function & its derivative at each step. Can be extended to the Newton MutiRoot method for solving multiple roots Can be easily applied to an of n-coupled set of non-linear equations – conduct a Taylor Series expansion of a function, dropping terms of order n, rewrite as a Jacobian matrix of PDs & convert to simultaneous linear equations !!! Secant Method http://en.wikipedia.org/wiki/Secant_method C++: http://forum.vcoderz.com/showthread.php?p=205230 Unlike N-R, can estimate first derivative from an initial interval (does not require root to be bracketed) instead of inputting it Since derivative is approximated, may converge slower. Is fast in practice as it does not have to evaluate the derivative at each step. Similar implementation to False Positive method Birge-Vieta Method http://mat.iitm.ac.in/home/sryedida/public_html/caimna/transcendental/polynomial%20methods/bv%20method.html C++: http://books.google.co.il/books?id=cL1boM2uyQwC&pg=SA3-PA51&lpg=SA3-PA51&dq=Birge-Vieta+Method+c%2B%2B&source=bl&ots=QZmnDTK3rC&sig=BPNcHHbpR_DKVoZXrLi4nVXD-gg&hl=en&sa=X&ei=R-_DUK2iNIjzsgbE5ID4Dg&redir_esc=y#v=onepage&q=Birge-Vieta%20Method%20c%2B%2B&f=false combines Horner's method of polynomial evaluation (transforming into lesser degree polynomials that are more computationally efficient to process) with Newton-Raphson to provide a computational speed-up Interpolation Overview Construct new data points for as close as possible fit within range of a discrete set of known points (that were obtained via sampling, experimentation) Use Taylor Series Expansion of a function f(x) around a specific value for x Linear Interpolation http://en.wikipedia.org/wiki/Linear_interpolation C++: http://www.hamaluik.com/?p=289 Straight line between 2 points à concatenate interpolants between each pair of data points Bilinear Interpolation http://en.wikipedia.org/wiki/Bilinear_interpolation C++: http://supercomputingblog.com/graphics/coding-bilinear-interpolation/2/ Extension of the linear function for interpolating functions of 2 variables – perform linear interpolation first in 1 direction, then in another. Used in image processing – e.g. texture mapping filter. Uses 4 vertices to interpolate a value within a unit cell. Lagrange Interpolation http://en.wikipedia.org/wiki/Lagrange_polynomial C++: http://www.codecogs.com/code/maths/approximation/interpolation/lagrange.php For polynomials Requires recomputation for all terms for each distinct x value – can only be applied for small number of nodes Numerically unstable Barycentric Interpolation http://epubs.siam.org/doi/pdf/10.1137/S0036144502417715 C++: http://www.gamedev.net/topic/621445-barycentric-coordinates-c-code-check/ Rearrange the terms in the equation of the Legrange interpolation by defining weight functions that are independent of the interpolated value of x Newton Divided Difference Interpolation http://en.wikipedia.org/wiki/Newton_polynomial C++: http://jee-appy.blogspot.co.il/2011/12/newton-divided-difference-interpolation.html Hermite Divided Differences: Interpolation polynomial approximation for a given set of data points in the NR form - divided differences are used to approximately calculate the various differences. For a given set of 3 data points , fit a quadratic interpolant through the data Bracketed functions allow Newton divided differences to be calculated recursively Difference table Cubic Spline Interpolation http://en.wikipedia.org/wiki/Spline_interpolation C++: https://www.marcusbannerman.co.uk/index.php/home/latestarticles/42-articles/96-cubic-spline-class.html Spline is a piecewise polynomial Provides smoothness – for interpolations with significantly varying data Use weighted coefficients to bend the function to be smooth & its 1st & 2nd derivatives are continuous through the edge points in the interval Curve Fitting A generalization of interpolating whereby given data points may contain noise à the curve does not necessarily pass through all the points Least Squares Fit http://en.wikipedia.org/wiki/Least_squares C++: http://www.ccas.ru/mmes/educat/lab04k/02/least-squares.c Residual – difference between observed value & expected value Model function is often chosen as a linear combination of the specified functions Determines: A) The model instance in which the sum of squared residuals has the least value B) param values for which model best fits data Straight Line Fit Linear correlation between independent variable and dependent variable Linear Regression http://en.wikipedia.org/wiki/Linear_regression C++: http://www.oocities.org/david_swaim/cpp/linregc.htm Special case of statistically exact extrapolation Leverage least squares Given a basis function, the sum of the residuals is determined and the corresponding gradient equation is expressed as a set of normal linear equations in matrix form that can be solved (e.g. using LU Decomposition) Can be weighted - Drop the assumption that all errors have the same significance –-> confidence of accuracy is different for each data point. Fit the function closer to points with higher weights Polynomial Fit - use a polynomial basis function Moving Average http://en.wikipedia.org/wiki/Moving_average C++: http://www.codeproject.com/Articles/17860/A-Simple-Moving-Average-Algorithm Used for smoothing (cancel fluctuations to highlight longer-term trends & cycles), time series data analysis, signal processing filters Replace each data point with average of neighbors. Can be simple (SMA), weighted (WMA), exponential (EMA). Lags behind latest data points – extra weight can be given to more recent data points. Weights can decrease arithmetically or exponentially according to distance from point. Parameters: smoothing factor, period, weight basis Optimization Overview Given function with multiple variables, find Min (or max by minimizing –f(x)) Iterative approach Efficient, but not necessarily reliable Conditions: noisy data, constraints, non-linear models Detection via sign of first derivative - Derivative of saddle points will be 0 Local minima Bisection method Similar method for finding a root for a non-linear equation Start with an interval that contains a minimum Golden Search method http://en.wikipedia.org/wiki/Golden_section_search C++: http://www.codecogs.com/code/maths/optimization/golden.php Bisect intervals according to golden ratio 0.618.. Achieves reduction by evaluating a single function instead of 2 Newton-Raphson Method Brent method http://en.wikipedia.org/wiki/Brent's_method C++: http://people.sc.fsu.edu/~jburkardt/cpp_src/brent/brent.cpp Based on quadratic or parabolic interpolation – if the function is smooth & parabolic near to the minimum, then a parabola fitted through any 3 points should approximate the minima – fails when the 3 points are collinear , in which case the denominator is 0 Simplex Method http://en.wikipedia.org/wiki/Simplex_algorithm C++: http://www.codeguru.com/cpp/article.php/c17505/Simplex-Optimization-Algorithm-and-Implemetation-in-C-Programming.htm Find the global minima of any multi-variable function Direct search – no derivatives required At each step it maintains a non-degenerative simplex – a convex hull of n+1 vertices. Obtains the minimum for a function with n variables by evaluating the function at n-1 points, iteratively replacing the point of worst result with the point of best result, shrinking the multidimensional simplex around the best point. Point replacement involves expanding & contracting the simplex near the worst value point to determine a better replacement point Oscillation can be avoided by choosing the 2nd worst result Restart if it gets stuck Parameters: contraction & expansion factors Simulated Annealing http://en.wikipedia.org/wiki/Simulated_annealing C++: http://code.google.com/p/cppsimulatedannealing/ Analogy to heating & cooling metal to strengthen its structure Stochastic method – apply random permutation search for global minima - Avoid entrapment in local minima via hill climbing Heating schedule - Annealing schedule params: temperature, iterations at each temp, temperature delta Cooling schedule – can be linear, step-wise or exponential Differential Evolution http://en.wikipedia.org/wiki/Differential_evolution C++: http://www.amichel.com/de/doc/html/ More advanced stochastic methods analogous to biological processes: Genetic algorithms, evolution strategies Parallel direct search method against multiple discrete or continuous variables Initial population of variable vectors chosen randomly – if weighted difference vector of 2 vectors yields a lower objective function value then it replaces the comparison vector Many params: #parents, #variables, step size, crossover constant etc Convergence is slow – many more function evaluations than simulated annealing Numerical Differentiation Overview 2 approaches to finite difference methods: · A) approximate function via polynomial interpolation then differentiate · B) Taylor series approximation – additionally provides error estimate Finite Difference methods http://en.wikipedia.org/wiki/Finite_difference_method C++: http://www.wpi.edu/Pubs/ETD/Available/etd-051807-164436/unrestricted/EAMPADU.pdf Find differences between high order derivative values - Approximate differential equations by finite differences at evenly spaced data points Based on forward & backward Taylor series expansion of f(x) about x plus or minus multiples of delta h. Forward / backward difference - the sums of the series contains even derivatives and the difference of the series contains odd derivatives – coupled equations that can be solved. Provide an approximation of the derivative within a O(h^2) accuracy There is also central difference & extended central difference which has a O(h^4) accuracy Richardson Extrapolation http://en.wikipedia.org/wiki/Richardson_extrapolation C++: http://mathscoding.blogspot.co.il/2012/02/introduction-richardson-extrapolation.html A sequence acceleration method applied to finite differences Fast convergence, high accuracy O(h^4) Derivatives via Interpolation Cannot apply Finite Difference method to discrete data points at uneven intervals – so need to approximate the derivative of f(x) using the derivative of the interpolant via 3 point Lagrange Interpolation Note: the higher the order of the derivative, the lower the approximation precision Numerical Integration Estimate finite & infinite integrals of functions More accurate procedure than numerical differentiation Use when it is not possible to obtain an integral of a function analytically or when the function is not given, only the data points are Newton Cotes Methods http://en.wikipedia.org/wiki/Newton%E2%80%93Cotes_formulas C++: http://www.siafoo.net/snippet/324 For equally spaced data points Computationally easy – based on local interpolation of n rectangular strip areas that is piecewise fitted to a polynomial to get the sum total area Evaluate the integrand at n+1 evenly spaced points – approximate definite integral by Sum Weights are derived from Lagrange Basis polynomials Leverage Trapezoidal Rule for default 2nd formulas, Simpson 1/3 Rule for substituting 3 point formulas, Simpson 3/8 Rule for 4 point formulas. For 4 point formulas use Bodes Rule. Higher orders obtain more accurate results Trapezoidal Rule uses simple area, Simpsons Rule replaces the integrand f(x) with a quadratic polynomial p(x) that uses the same values as f(x) for its end points, but adds a midpoint Romberg Integration http://en.wikipedia.org/wiki/Romberg's_method C++: http://code.google.com/p/romberg-integration/downloads/detail?name=romberg.cpp&can=2&q= Combines trapezoidal rule with Richardson Extrapolation Evaluates the integrand at equally spaced points The integrand must have continuous derivatives Each R(n,m) extrapolation uses a higher order integrand polynomial replacement rule (zeroth starts with trapezoidal) à a lower triangular matrix set of equation coefficients where the bottom right term has the most accurate approximation. The process continues until the difference between 2 successive diagonal terms becomes sufficiently small. Gaussian Quadrature http://en.wikipedia.org/wiki/Gaussian_quadrature C++: http://www.alglib.net/integration/gaussianquadratures.php Data points are chosen to yield best possible accuracy – requires fewer evaluations Ability to handle singularities, functions that are difficult to evaluate The integrand can include a weighting function determined by a set of orthogonal polynomials. Points & weights are selected so that the integrand yields the exact integral if f(x) is a polynomial of degree <= 2n+1 Techniques (basically different weighting functions): · Gauss-Legendre Integration w(x)=1 · Gauss-Laguerre Integration w(x)=e^-x · Gauss-Hermite Integration w(x)=e^-x^2 · Gauss-Chebyshev Integration w(x)= 1 / Sqrt(1-x^2) Solving ODEs Use when high order differential equations cannot be solved analytically Evaluated under boundary conditions RK for systems – a high order differential equation can always be transformed into a coupled first order system of equations Euler method http://en.wikipedia.org/wiki/Euler_method C++: http://rosettacode.org/wiki/Euler_method First order Runge–Kutta method. Simple recursive method – given an initial value, calculate derivative deltas. Unstable & not very accurate (O(h) error) – not used in practice A first-order method - the local error (truncation error per step) is proportional to the square of the step size, and the global error (error at a given time) is proportional to the step size In evolving solution between data points xn & xn+1, only evaluates derivatives at beginning of interval xn à asymmetric at boundaries Higher order Runge Kutta http://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods C++: http://www.dreamincode.net/code/snippet1441.htm 2nd & 4th order RK - Introduces parameterized midpoints for more symmetric solutions à accuracy at higher computational cost Adaptive RK – RK-Fehlberg – estimate the truncation at each integration step & automatically adjust the step size to keep error within prescribed limits. At each step 2 approximations are compared – if in disagreement to a specific accuracy, the step size is reduced Boundary Value Problems Where solution of differential equations are located at 2 different values of the independent variable x à more difficult, because cannot just start at point of initial value – there may not be enough starting conditions available at the end points to produce a unique solution An n-order equation will require n boundary conditions – need to determine the missing n-1 conditions which cause the given conditions at the other boundary to be satisfied Shooting Method http://en.wikipedia.org/wiki/Shooting_method C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-shooting-method-for-solving.html Iteratively guess the missing values for one end & integrate, then inspect the discrepancy with the boundary values of the other end to adjust the estimate Given the starting boundary values u1 & u2 which contain the root u, solve u given the false position method (solving the differential equation as an initial value problem via 4th order RK), then use u to solve the differential equations. Finite Difference Method For linear & non-linear systems Higher order derivatives require more computational steps – some combinations for boundary conditions may not work though Improve the accuracy by increasing the number of mesh points Solving EigenValue Problems An eigenvalue can substitute a matrix when doing matrix multiplication à convert matrix multiplication into a polynomial EigenValue For a given set of equations in matrix form, determine what are the solution eigenvalue & eigenvectors Similar Matrices - have same eigenvalues. Use orthogonal similarity transforms to reduce a matrix to diagonal form from which eigenvalue(s) & eigenvectors can be computed iteratively Jacobi method http://en.wikipedia.org/wiki/Jacobi_method C++: http://people.sc.fsu.edu/~jburkardt/classes/acs2_2008/openmp/jacobi/jacobi.html Robust but Computationally intense – use for small matrices < 10x10 Power Iteration http://en.wikipedia.org/wiki/Power_iteration For any given real symmetric matrix, generate the largest single eigenvalue & its eigenvectors Simplest method – does not compute matrix decomposition à suitable for large, sparse matrices Inverse Iteration Variation of power iteration method – generates the smallest eigenvalue from the inverse matrix Rayleigh Method http://en.wikipedia.org/wiki/Rayleigh's_method_of_dimensional_analysis Variation of power iteration method Rayleigh Quotient Method Variation of inverse iteration method Matrix Tri-diagonalization Method Use householder algorithm to reduce an NxN symmetric matrix to a tridiagonal real symmetric matrix vua N-2 orthogonal transforms     Whats Next Outside of Numerical Methods there are lots of different types of algorithms that I’ve learned over the decades: Data Mining – (I covered this briefly in a previous post: http://geekswithblogs.net/JoshReuben/archive/2007/12/31/ssas-dm-algorithms.aspx ) Search & Sort Routing Problem Solving Logical Theorem Proving Planning Probabilistic Reasoning Machine Learning Solvers (eg MIP) Bioinformatics (Sequence Alignment, Protein Folding) Quant Finance (I read Wilmott’s books – interesting) Sooner or later, I’ll cover the above topics as well.

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  • Diving into OpenStack Network Architecture - Part 2 - Basic Use Cases

    - by Ronen Kofman
      rkofman Normal rkofman 4 138 2014-06-05T03:38:00Z 2014-06-05T05:04:00Z 3 2735 15596 Oracle Corporation 129 36 18295 12.00 Clean Clean false false false false EN-US X-NONE HE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi; mso-bidi-language:AR-SA;} In the previous post we reviewed several network components including Open vSwitch, Network Namespaces, Linux Bridges and veth pairs. In this post we will take three simple use cases and see how those basic components come together to create a complete SDN solution in OpenStack. With those three use cases we will review almost the entire network setup and see how all the pieces work together. The use cases we will use are: 1.       Create network – what happens when we create network and how can we create multiple isolated networks 2.       Launch a VM – once we have networks we can launch VMs and connect them to networks. 3.       DHCP request from a VM – OpenStack can automatically assign IP addresses to VMs. This is done through local DHCP service controlled by OpenStack Neutron. We will see how this service runs and how does a DHCP request and response look like. In this post we will show connectivity, we will see how packets get from point A to point B. We first focus on how a configured deployment looks like and only later we will discuss how and when the configuration is created. Personally I found it very valuable to see the actual interfaces and how they connect to each other through examples and hands on experiments. After the end game is clear and we know how the connectivity works, in a later post, we will take a step back and explain how Neutron configures the components to be able to provide such connectivity.  We are going to get pretty technical shortly and I recommend trying these examples on your own deployment or using the Oracle OpenStack Tech Preview. Understanding these three use cases thoroughly and how to look at them will be very helpful when trying to debug a deployment in case something does not work. Use case #1: Create Network Create network is a simple operation it can be performed from the GUI or command line. When we create a network in OpenStack the network is only available to the tenant who created it or it could be defined as “shared” and then it can be used by all tenants. A network can have multiple subnets but for this demonstration purpose and for simplicity we will assume that each network has exactly one subnet. Creating a network from the command line will look like this: # neutron net-create net1 Created a new network: +---------------------------+--------------------------------------+ | Field                     | Value                                | +---------------------------+--------------------------------------+ | admin_state_up            | True                                 | | id                        | 5f833617-6179-4797-b7c0-7d420d84040c | | name                      | net1                                 | | provider:network_type     | vlan                                 | | provider:physical_network | default                              | | provider:segmentation_id  | 1000                                 | | shared                    | False                                | | status                    | ACTIVE                               | | subnets                   |                                      | | tenant_id                 | 9796e5145ee546508939cd49ad59d51f     | +---------------------------+--------------------------------------+ Creating a subnet for this network will look like this: # neutron subnet-create net1 10.10.10.0/24 Created a new subnet: +------------------+------------------------------------------------+ | Field            | Value                                          | +------------------+------------------------------------------------+ | allocation_pools | {"start": "10.10.10.2", "end": "10.10.10.254"} | | cidr             | 10.10.10.0/24                                  | | dns_nameservers  |                                                | | enable_dhcp      | True                                           | | gateway_ip       | 10.10.10.1                                     | | host_routes      |                                                | | id               | 2d7a0a58-0674-439a-ad23-d6471aaae9bc           | | ip_version       | 4                                              | | name             |                                                | | network_id       | 5f833617-6179-4797-b7c0-7d420d84040c           | | tenant_id        | 9796e5145ee546508939cd49ad59d51f               | +------------------+------------------------------------------------+ We now have a network and a subnet, on the network topology view this looks like this: Now let’s dive in and see what happened under the hood. Looking at the control node we will discover that a new namespace was created: # ip netns list qdhcp-5f833617-6179-4797-b7c0-7d420d84040c   The name of the namespace is qdhcp-<network id> (see above), let’s look into the namespace and see what’s in it: # ip netns exec qdhcp-5f833617-6179-4797-b7c0-7d420d84040c ip addr 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00     inet 127.0.0.1/8 scope host lo     inet6 ::1/128 scope host        valid_lft forever preferred_lft forever 12: tap26c9b807-7c: <BROADCAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN     link/ether fa:16:3e:1d:5c:81 brd ff:ff:ff:ff:ff:ff     inet 10.10.10.3/24 brd 10.10.10.255 scope global tap26c9b807-7c     inet6 fe80::f816:3eff:fe1d:5c81/64 scope link        valid_lft forever preferred_lft forever   We see two interfaces in the namespace, one is the loopback and the other one is an interface called “tap26c9b807-7c”. This interface has the IP address of 10.10.10.3 and it will also serve dhcp requests in a way we will see later. Let’s trace the connectivity of the “tap26c9b807-7c” interface from the namespace.  First stop is OVS, we see that the interface connects to bridge  “br-int” on OVS: # ovs-vsctl show 8a069c7c-ea05-4375-93e2-b9fc9e4b3ca1     Bridge "br-eth2"         Port "br-eth2"             Interface "br-eth2"                 type: internal         Port "eth2"             Interface "eth2"         Port "phy-br-eth2"             Interface "phy-br-eth2"     Bridge br-ex         Port br-ex             Interface br-ex                 type: internal     Bridge br-int         Port "int-br-eth2"             Interface "int-br-eth2"         Port "tap26c9b807-7c"             tag: 1             Interface "tap26c9b807-7c"                 type: internal         Port br-int             Interface br-int                 type: internal     ovs_version: "1.11.0"   In the picture above we have a veth pair which has two ends called “int-br-eth2” and "phy-br-eth2", this veth pair is used to connect two bridge in OVS "br-eth2" and "br-int". In the previous post we explained how to check the veth connectivity using the ethtool command. It shows that the two are indeed a pair: # ethtool -S int-br-eth2 NIC statistics:      peer_ifindex: 10 . .   #ip link . . 10: phy-br-eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 . . Note that “phy-br-eth2” is connected to a bridge called "br-eth2" and one of this bridge's interfaces is the physical link eth2. This means that the network which we have just created has created a namespace which is connected to the physical interface eth2. eth2 is the “VM network” the physical interface where all the virtual machines connect to where all the VMs are connected. About network isolation: OpenStack supports creation of multiple isolated networks and can use several mechanisms to isolate the networks from one another. The isolation mechanism can be VLANs, VxLANs or GRE tunnels, this is configured as part of the initial setup in our deployment we use VLANs. When using VLAN tagging as an isolation mechanism a VLAN tag is allocated by Neutron from a pre-defined VLAN tags pool and assigned to the newly created network. By provisioning VLAN tags to the networks Neutron allows creation of multiple isolated networks on the same physical link.  The big difference between this and other platforms is that the user does not have to deal with allocating and managing VLANs to networks. The VLAN allocation and provisioning is handled by Neutron which keeps track of the VLAN tags, and responsible for allocating and reclaiming VLAN tags. In the example above net1 has the VLAN tag 1000, this means that whenever a VM is created and connected to this network the packets from that VM will have to be tagged with VLAN tag 1000 to go on this particular network. This is true for namespace as well, if we would like to connect a namespace to a particular network we have to make sure that the packets to and from the namespace are correctly tagged when they reach the VM network. In the example above we see that the namespace interface “tap26c9b807-7c” has vlan tag 1 assigned to it, if we examine OVS we see that it has flows which modify VLAN tag 1 to VLAN tag 1000 when a packet goes to the VM network on eth2 and vice versa. We can see this using the dump-flows command on OVS for packets going to the VM network we see the modification done on br-eth2: #  ovs-ofctl dump-flows br-eth2 NXST_FLOW reply (xid=0x4):  cookie=0x0, duration=18669.401s, table=0, n_packets=857, n_bytes=163350, idle_age=25, priority=4,in_port=2,dl_vlan=1 actions=mod_vlan_vid:1000,NORMAL  cookie=0x0, duration=165108.226s, table=0, n_packets=14, n_bytes=1000, idle_age=5343, hard_age=65534, priority=2,in_port=2 actions=drop  cookie=0x0, duration=165109.813s, table=0, n_packets=1671, n_bytes=213304, idle_age=25, hard_age=65534, priority=1 actions=NORMAL   For packets coming from the interface to the namespace we see the following modification: #  ovs-ofctl dump-flows br-int NXST_FLOW reply (xid=0x4):  cookie=0x0, duration=18690.876s, table=0, n_packets=1610, n_bytes=210752, idle_age=1, priority=3,in_port=1,dl_vlan=1000 actions=mod_vlan_vid:1,NORMAL  cookie=0x0, duration=165130.01s, table=0, n_packets=75, n_bytes=3686, idle_age=4212, hard_age=65534, priority=2,in_port=1 actions=drop  cookie=0x0, duration=165131.96s, table=0, n_packets=863, n_bytes=160727, idle_age=1, hard_age=65534, priority=1 actions=NORMAL   To summarize we can see that when a user creates a network Neutron creates a namespace and this namespace is connected through OVS to the “VM network”. OVS also takes care of tagging the packets from the namespace to the VM network with the correct VLAN tag and knows to modify the VLAN for packets coming from VM network to the namespace. Now let’s see what happens when a VM is launched and how it is connected to the “VM network”. Use case #2: Launch a VM Launching a VM can be done from Horizon or from the command line this is how we do it from Horizon: Attach the network: And Launch Once the virtual machine is up and running we can see the associated IP using the nova list command : # nova list +--------------------------------------+--------------+--------+------------+-------------+-----------------+ | ID                                   | Name         | Status | Task State | Power State | Networks        | +--------------------------------------+--------------+--------+------------+-------------+-----------------+ | 3707ac87-4f5d-4349-b7ed-3a673f55e5e1 | Oracle Linux | ACTIVE | None       | Running     | net1=10.10.10.2 | +--------------------------------------+--------------+--------+------------+-------------+-----------------+ The nova list command shows us that the VM is running and that the IP 10.10.10.2 is assigned to this VM. Let’s trace the connectivity from the VM to VM network on eth2 starting with the VM definition file. The configuration files of the VM including the virtual disk(s), in case of ephemeral storage, are stored on the compute node at/var/lib/nova/instances/<instance-id>/. Looking into the VM definition file ,libvirt.xml,  we see that the VM is connected to an interface called “tap53903a95-82” which is connected to a Linux bridge called “qbr53903a95-82”: <interface type="bridge">       <mac address="fa:16:3e:fe:c7:87"/>       <source bridge="qbr53903a95-82"/>       <target dev="tap53903a95-82"/>     </interface>   Looking at the bridge using the brctl show command we see this: # brctl show bridge name     bridge id               STP enabled     interfaces qbr53903a95-82          8000.7e7f3282b836       no              qvb53903a95-82                                                         tap53903a95-82    The bridge has two interfaces, one connected to the VM (“tap53903a95-82 “) and another one ( “qvb53903a95-82”) connected to “br-int” bridge on OVS: # ovs-vsctl show 83c42f80-77e9-46c8-8560-7697d76de51c     Bridge "br-eth2"         Port "br-eth2"             Interface "br-eth2"                 type: internal         Port "eth2"             Interface "eth2"         Port "phy-br-eth2"             Interface "phy-br-eth2"     Bridge br-int         Port br-int             Interface br-int                 type: internal         Port "int-br-eth2"             Interface "int-br-eth2"         Port "qvo53903a95-82"             tag: 3             Interface "qvo53903a95-82"     ovs_version: "1.11.0"   As we showed earlier “br-int” is connected to “br-eth2” on OVS using the veth pair int-br-eth2,phy-br-eth2 and br-eth2 is connected to the physical interface eth2. The whole flow end to end looks like this: VM è tap53903a95-82 (virtual interface)è qbr53903a95-82 (Linux bridge) è qvb53903a95-82 (interface connected from Linux bridge to OVS bridge br-int) è int-br-eth2 (veth one end) è phy-br-eth2 (veth the other end) è eth2 physical interface. The purpose of the Linux Bridge connecting to the VM is to allow security group enforcement with iptables. Security groups are enforced at the edge point which are the interface of the VM, since iptables nnot be applied to OVS bridges we use Linux bridge to apply them. In the future we hope to see this Linux Bridge going away rules.  VLAN tags: As we discussed in the first use case net1 is using VLAN tag 1000, looking at OVS above we see that qvo41f1ebcf-7c is tagged with VLAN tag 3. The modification from VLAN tag 3 to 1000 as we go to the physical network is done by OVS  as part of the packet flow of br-eth2 in the same way we showed before. To summarize, when a VM is launched it is connected to the VM network through a chain of elements as described here. During the packet from VM to the network and back the VLAN tag is modified. Use case #3: Serving a DHCP request coming from the virtual machine In the previous use cases we have shown that both the namespace called dhcp-<some id> and the VM end up connecting to the physical interface eth2  on their respective nodes, both will tag their packets with VLAN tag 1000.We saw that the namespace has an interface with IP of 10.10.10.3. Since the VM and the namespace are connected to each other and have interfaces on the same subnet they can ping each other, in this picture we see a ping from the VM which was assigned 10.10.10.2 to the namespace: The fact that they are connected and can ping each other can become very handy when something doesn’t work right and we need to isolate the problem. In such case knowing that we should be able to ping from the VM to the namespace and back can be used to trace the disconnect using tcpdump or other monitoring tools. To serve DHCP requests coming from VMs on the network Neutron uses a Linux tool called “dnsmasq”,this is a lightweight DNS and DHCP service you can read more about it here. If we look at the dnsmasq on the control node with the ps command we see this: dnsmasq --no-hosts --no-resolv --strict-order --bind-interfaces --interface=tap26c9b807-7c --except-interface=lo --pid-file=/var/lib/neutron/dhcp/5f833617-6179-4797-b7c0-7d420d84040c/pid --dhcp-hostsfile=/var/lib/neutron/dhcp/5f833617-6179-4797-b7c0-7d420d84040c/host --dhcp-optsfile=/var/lib/neutron/dhcp/5f833617-6179-4797-b7c0-7d420d84040c/opts --leasefile-ro --dhcp-range=tag0,10.10.10.0,static,120s --dhcp-lease-max=256 --conf-file= --domain=openstacklocal The service connects to the tap interface in the namespace (“--interface=tap26c9b807-7c”), If we look at the hosts file we see this: # cat  /var/lib/neutron/dhcp/5f833617-6179-4797-b7c0-7d420d84040c/host fa:16:3e:fe:c7:87,host-10-10-10-2.openstacklocal,10.10.10.2   If you look at the console output above you can see the MAC address fa:16:3e:fe:c7:87 which is the VM MAC. This MAC address is mapped to IP 10.10.10.2 and so when a DHCP request comes with this MAC dnsmasq will return the 10.10.10.2.If we look into the namespace at the time we initiate a DHCP request from the VM (this can be done by simply restarting the network service in the VM) we see the following: # ip netns exec qdhcp-5f833617-6179-4797-b7c0-7d420d84040c tcpdump -n 19:27:12.191280 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from fa:16:3e:fe:c7:87, length 310 19:27:12.191666 IP 10.10.10.3.bootps > 10.10.10.2.bootpc: BOOTP/DHCP, Reply, length 325   To summarize, the DHCP service is handled by dnsmasq which is configured by Neutron to listen to the interface in the DHCP namespace. Neutron also configures dnsmasq with the combination of MAC and IP so when a DHCP request comes along it will receive the assigned IP. Summary In this post we relied on the components described in the previous post and saw how network connectivity is achieved using three simple use cases. These use cases gave a good view of the entire network stack and helped understand how an end to end connection is being made between a VM on a compute node and the DHCP namespace on the control node. One conclusion we can draw from what we saw here is that if we launch a VM and it is able to perform a DHCP request and receive a correct IP then there is reason to believe that the network is working as expected. We saw that a packet has to travel through a long list of components before reaching its destination and if it has done so successfully this means that many components are functioning properly. In the next post we will look at some more sophisticated services Neutron supports and see how they work. We will see that while there are some more components involved for the most part the concepts are the same. @RonenKofman

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  • Java ?????????????!

    - by OTN-J Master
    OTN Japan Newsletter 5??????????????Java????!???????????Java???????!??????????????????????????????????????????????????????20?????Beginning Java EE??????????????? ?????????????????2???????1?????Java Magazine ????????????????????????????????????????????2?????????Java?????????????????????????????? ?????????????????????Java?????????????????????????????????? (Java Magaine??) ?????????????????OTN???????????????·??????????????????????????????????????Java Magazine??????????????????????OTN Japan Newsletter???????????????????????????????????????(>> OTN Japan Newsletter???????) ????????????????·?????????????????????? Java Magazine????????????????????????????????????? ??????????????????????????? ?????????????????? ??????????????????????????????????? ??oracleDB?????????????????????? ????????????? ??????????????????????????????????????? ???????????????????????????????????????????? ????Web???????????????????? ???API??????????????????????????????? Java???????????????????????????????JavaMail?GlassFish??????????? ??????????????????????????????????? ???????????????????????????????? Java???????????????????????????? ?????JavaMail???????????????????????????????????????????????????? ???API????????????? JavaFX??????????????????????????????????? ??Swing?????????????????SWT?????????????????????????????????????? ???????????????????????????????????????????????????????????? Java?????????????????????????????????????????? ?????????Web?????????????????????????????????????????????????????????? OTN????Java?????????????????????????? ??????? ??????????????????????? ???????????????????????? ??????????????? ????????????????????????????????? ??Web??xx??????yy??????????????????????????FAQ??????????????????????????? ???????????????????????????????????(?????????????????…) ????????????????????????????????????? Java????????????????????????? ????????????RSS???????????????? ??????Java?????????????????????????????????????????? ???????????????? ???????????????????????????? ???????????????? ????????????????? JAVA??????????????????????????????????????????????????????????????? ?????????????????????????????????????????????? ???Java????????????????????·??·???????????????????????? Oracle???????????????? Oracle???????????????? ?????????????????????????????????? ???????????????????????? ???????????IDE??? ????PG?????????????????????QA??? Java?Version?????????????????????????????????????????????? ??????????????????????????? SUN????????????????????????????????? ??????????Oracle?????????????????????????? ?????Java???????????????????????? ???Java?????????????????????????????·???????·?????????????????????????? Java??????????????????????????????????????????????????????? ?????????Java???????????? ???????????????????????????? ?????????????????????????????????? google?????????Java???????(?open)?????????????????????? ????????????????????????????????????? ·?????????????????????????(??????????) ·RSS????????????????????????????????? ·??????????????????????????????????????????????????? Java??????????????????????????????????????????????????????????????????????????????? ??????????????????????????????? ?????????????????????????????????????????????????????????????????????

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  • Websphere federated repository for Active Directory

    - by Drakiula
    Hi, What I am trying to achieve is to have Websphere 6.1 use Active Directory users authentication. Websphere is running on Windows 2008 R2. What I've done already: Succesfully setup a federated repository for Windows Active Directory (LDAP); Create a realm definition for the federated repository previously defined; Set the realm definition as the current real definition. Stop the Websphere service. When I attempt to start the Websphere service again, it crashes with the following stacktrace: ------Start of DE processing------ = [9/3/10 2:36:14:133 PDT] , key = com.ibm.websphere.security.EntryNotFoundException com.ibm.ws.security.registry.UserRegistryImpl.createCredential 824 Exception = com.ibm.websphere.security.EntryNotFoundException Source = com.ibm.ws.security.registry.UserRegistryImpl.createCredential probeid = 824 Stack Dump = com.ibm.websphere.wim.exception.EntityNotFoundException: CWWIM4001E The 'null' entity was not found. at com.ibm.ws.wim.registry.util.UniqueIdBridge.getUniqueUserId(UniqueIdBridge.java:233) at com.ibm.ws.wim.registry.WIMUserRegistry$6.run(WIMUserRegistry.java:351) at com.ibm.ws.wim.security.authz.jacc.JACCSecurityManager.runAsSuperUser(JACCSecurityManager.java:500) at com.ibm.ws.wim.security.authz.ProfileSecurityManager.runAsSuperUser(ProfileSecurityManager.java:964) at com.ibm.ws.wim.registry.WIMUserRegistry.getUniqueUserId(WIMUserRegistry.java:340) at com.ibm.ws.security.registry.UserRegistryImpl.createCredential(UserRegistryImpl.java:750) at com.ibm.ws.security.ltpa.LTPAServerObject.authenticate(LTPAServerObject.java:776) at com.ibm.ws.security.server.lm.ltpaLoginModule.login(ltpaLoginModule.java:453) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:79) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:618) at javax.security.auth.login.LoginContext.invoke(LoginContext.java:795) at javax.security.auth.login.LoginContext.access$000(LoginContext.java:209) at javax.security.auth.login.LoginContext$4.run(LoginContext.java:709) at java.security.AccessController.doPrivileged(AccessController.java:246) at javax.security.auth.login.LoginContext.invokePriv(LoginContext.java:706) at javax.security.auth.login.LoginContext.login(LoginContext.java:603) at com.ibm.ws.security.auth.JaasLoginHelper.jaas_login(JaasLoginHelper.java:376) at com.ibm.ws.security.auth.ContextManagerImpl.login(ContextManagerImpl.java:3513) at com.ibm.ws.security.auth.ContextManagerImpl.login(ContextManagerImpl.java:3306) at com.ibm.ws.security.auth.ContextManagerImpl.login(ContextManagerImpl.java:3086) at com.ibm.ws.security.auth.ContextManagerImpl.getServerSubjectInternal(ContextManagerImpl.java:2180) at com.ibm.ws.security.auth.ContextManagerImpl.getServerSubjectInternal(ContextManagerImpl.java:1972) at com.ibm.ws.security.auth.ContextManagerImpl.initialize(ContextManagerImpl.java:2530) at com.ibm.ws.security.auth.ContextManagerImpl.initialize(ContextManagerImpl.java:2560) at com.ibm.ws.security.core.SecurityContext.enable(SecurityContext.java:83) at com.ibm.ws.security.core.distSecurityComponentImpl.initialize(distSecurityComponentImpl.java:379) at com.ibm.ws.security.core.distSecurityComponentImpl.startSecurity(distSecurityComponentImpl.java:336) at com.ibm.ws.security.core.SecurityComponentImpl.startSecurity(SecurityComponentImpl.java:105) at com.ibm.ws.security.core.ServerSecurityComponentImpl.start(ServerSecurityComponentImpl.java:283) at com.ibm.ws.runtime.component.ContainerImpl.startComponents(ContainerImpl.java:977) at com.ibm.ws.runtime.component.ContainerImpl.start(ContainerImpl.java:673) at com.ibm.ws.runtime.component.ApplicationServerImpl.start(ApplicationServerImpl.java:197) at com.ibm.ws.runtime.component.ContainerImpl.startComponents(ContainerImpl.java:977) at com.ibm.ws.runtime.component.ContainerImpl.start(ContainerImpl.java:673) at com.ibm.ws.runtime.component.ServerImpl.start(ServerImpl.java:526) at com.ibm.ws.runtime.WsServerImpl.bootServerContainer(WsServerImpl.java:192) at com.ibm.ws.runtime.WsServerImpl.start(WsServerImpl.java:140) at com.ibm.ws.runtime.WsServerImpl.main(WsServerImpl.java:461) at com.ibm.ws.runtime.WsServer.main(WsServer.java:59) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:79) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:618) at com.ibm.wsspi.bootstrap.WSLauncher.launchMain(WSLauncher.java:183) at com.ibm.wsspi.bootstrap.WSLauncher.main(WSLauncher.java:90) at com.ibm.wsspi.bootstrap.WSLauncher.run(WSLauncher.java:72) at org.eclipse.core.internal.runtime.PlatformActivator$1.run(PlatformActivator.java:78) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:92) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:68) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:400) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:177) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:79) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:618) at org.eclipse.core.launcher.Main.invokeFramework(Main.java:336) at org.eclipse.core.launcher.Main.basicRun(Main.java:280) at org.eclipse.core.launcher.Main.run(Main.java:977) at com.ibm.wsspi.bootstrap.WSPreLauncher.launchEclipse(WSPreLauncher.java:329) at com.ibm.wsspi.bootstrap.WSPreLauncher.main(WSPreLauncher.java:92) Dump of callerThis = Object type = com.ibm.ws.security.registry.UserRegistryImpl com.ibm.ws.security.registry.UserRegistryImpl@68a068a0 Anybody maybe has a hint on this? I followed the exact steps described in the IBM Infocenter for setting this up. Thanks in advance for the help.

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  • Riak "error":"insufficient_vnodes_available"

    - by Wolfiem
    We have 4 nodes Riak installation. They are running on Ubuntu 12.04 LTS Precise installed servers. We have installed 1.1.4 at August 1st 2012 and upgraded 1.2.0 when its available. Server names are: f1 - 10.10.0.12 - This is the first installed server. We have joined other ones to this server. This also serves Riak control. s2 - 10.10.0.22 - s3 - 10.10.0.23 - s4 - 10.10.0.24 - This server also serves Riak control. This morning we've seen "insufficient nodes available" error at our applications log and restarted all nodes. 3 of them became available except "f1" UPDATE : while I prepare this message live 3 nodes became unavailable and need restart Riak. wolfiem@f01:~$ sudo /etc/init.d/riak start Riak failed to start within 15 seconds, see the output of 'riak console' for more information. If you want to wait longer, set the environment variable WAIT_FOR_ERLANG to the number of seconds to wait. I've tried to set WAIT_FOR_ERLANG value to 60 seconds but I can't. adding this line in vm.args didn't work: -env WAIT_FOR_ERLANG 60 I also tried to set this from terminal but it didn't work either. wolfiem@f01:~$ export WAIT_FOR_ERLANG=60 It still says "Riak failed to start within 15 seconds" This is the console.log output: 2012-09-11 10:58:02.532 [info] <0.7.0> Application lager started on node '[email protected]' 2012-09-11 10:58:02.560 [warning] <0.148.0>@riak_core_ring_manager:reload_ring:231 No ring file available. 2012-09-11 10:58:02.585 [error] <0.164.0> CRASH REPORT Process <0.164.0> with 0 neighbours exited with reason: eaddrnotavail in gen_server:init_it/6 line 320 This is the error.log output 2012-09-11 10:58:02.585 [error] <0.164.0> CRASH REPORT Process <0.164.0> with 0 neighbours exited with reason: eaddrnotavail in gen_server:init_it/6 line 320 This is the crash.log output: 2012-09-11 10:58:02 =CRASH REPORT==== crasher: initial call: mochiweb_socket_server:init/1 pid: <0.164.0> registered_name: [] exception exit: {eaddrnotavail,[{gen_server,init_it,6,[{file,"gen_server.erl"},{line,320}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,227}]}]} ancestors: [riak_core_sup,<0.135.0>] messages: [] links: [<0.136.0>] dictionary: [] trap_exit: true status: running heap_size: 377 stack_size: 24 reductions: 403 neighbours: You can find the riak console output below: wolfiem@f01:~$ riak console Attempting to restart script through sudo -H -u riak Exec: /usr/lib/riak/erts-5.9.1/bin/erlexec -boot /usr/lib/riak/releases/1.2.0/riak -embedded -config /etc/riak/app.config -pa /usr/lib/riak/basho-patches -args_file /etc/riak/vm.args -- console Root: /usr/lib/riak Erlang R15B01 (erts-5.9.1) [source] [64-bit] [smp:8:8] [async-threads:64] [kernel-poll:true] =INFO REPORT==== 11-Sep-2012::10:44:18 === alarm_handler: {set,{system_memory_high_watermark,[]}} ** /usr/lib/riak/lib/observer-1.1/ebin/etop_txt.beam hides /usr/lib/riak/lib/basho-patches/etop_txt.beam ** Found 1 name clashes in code paths 10:44:19.099 [info] Application lager started on node '[email protected]' 10:44:19.130 [warning] No ring file available. 10:44:19.158 [error] CRASH REPORT Process <0.164.0> with 0 neighbours exited with reason: eaddrnotavail in gen_server:init_it/6 line 320 /usr/lib/riak/lib/os_mon-2.2.9/priv/bin/memsup: Erlang has closed. =INFO REPORT==== 11-Sep-2012::10:44:19 === alarm_handler: {clear,system_memory_high_watermark} Erlang has closed {"Kernel pid terminated",application_controller,"{application_start_failure,riak_core,{shutdown,{riak_core_app,start,[normal,[]]}}}"} Crash dump was written to: /var/log/riak/erl_crash.dump Kernel pid terminated (application_controller) ({application_start_failure,riak_core,{shutdown,{riak_core_app,start,[normal,[]]}}})

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