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• GCC destructor behaviour

  - by joveha

  I've noticed a difference in behaviour for gcc's destructor when compiled under linux and crosscompiled with mingw. On linux the destructor will not get called unless the program terminates normally by itself (returns from main). I guess that kind of makes sense if you take signal handlers into account. On Win32 however, the destructor is called if the program is terminated by say a CTRL-C, but not when killed from the Task Manager. Why is this? And what would you suggest to make the destructor get called no matter how the process terminates - on Win32 in particular? Example code: #include <stdio.h> int main(int argc, char **argv) { printf("main\n"); while(1) {} return 0; } __attribute__((destructor)) static void mydestructor(void) { printf("destructor\n"); }

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• Paypal IPN Confirmation Screen immediately after redirect without reload

  - by Email

  Hi I made a script for IPN which works great but how can i immediately notify the user? I mean paypal redirects the customer to a custom-page i can define, simultanously my ipn.php checked the status, BUT how can i immediately tell the customer on this custom-page that it was successful or not. this custom-page does somehow has to know that this is the customer-xyz which made the ipn-verified!!! payment xyz, but how? i think also this custom-page redirect should wait the 5 seconds because php does only process files/request on-loads... so after 5 seconds the ipnscript surely did complete. Sorry if this question is too newby but i dont know how to notify the customer about the (ipn-verified!!!) payment-status immediately. How do you do this? Thanks so much

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• Passing Text for command line

  - by Kasun

  Hi, I need to pass some text which is in richtext box to command line. This is my Button click even which start the cmd. private void button1_Click(object sender, EventArgs e) { ProcessStartInfo psi = new ProcessStartInfo { FileName = "cmd", Arguments = @"/k ""C:\Program Files\Microsoft Visual Studio 9.0\VC\bin\vcvars32.bat""", }; Process.Start(psi); } In my rich text box contain following text. include iostream using namespace std; int main() { cout << "Welcome to the wonderful world of C++!!!\n"; return 0; } Can anyone provide me necessary codes.

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• CodePlex Daily Summary for Saturday, March 24, 2012

  CodePlex Daily Summary for Saturday, March 24, 2012Popular Releasesmenu4web: menu4web 0.0.3: menu4web 0.0.3Craig's Utility Library: Craig's Utility Library 3.1: This update adds about 60 new extension methods, a couple of new classes, and a number of fixes including: Additions Added DateSpan class Added GenericDelimited class Random additions Added static thread friendly version of Random.Next called ThreadSafeNext. AOP Manager additions Added Destroy function to AOPManager (clears out all data so system can be recreated. Really only useful for testing...) ORM additions Added PagedCommand and PageCount functions to ObjectBaseClass (same as M...SQL Monitor - managing sql server performance: SQLMon 4.2 alpha 14: 1. improved accuracy of logic fault checking in analysisMapWindow 6 Desktop GIS: MapWindow 6.1.1: MapWindow 6 Desktop GIS is an open source desktop GIS for Microsoft Windows that is built upon the DotSpatial Library. This release requires .Net 4 (Client Profile). Are you a software developer?Instead of downloading MapWindow for development purposes, get started with with the DotSpatial templateDotSpatial: DotSpatial 1.1: This is a Minor Release. See the changes in the issue tracker. Minimal -- includes DotSpatial core and essential extensions Extended -- includes debugging symbols and additional extensions Just want to run the software? End user (non-programmer) version available branded as MapWindow Want to add your own feature? Develop a plugin, using the template and contribute to the extension feed (you can also write extensions that you distribute in other ways). Components are available as NuGet pa...Indiefreaks Game Framework: 0.9.2.0: Feature: Added SunBurn engine v2.0.18.7 support (doesn't support versions below). Feature: Added GammaCorrection Post processor to allow developers or even players to tweak the Gamma of the game depending on their screen (courtesy of bamyazi) Feature: Added Windows, Xbox 360 & WP7 enabled StorageManager (based on Nick Gravelyn's EasyStorage) to read/write files for player or game data. Feature: Added VirtualGamePad feature for WP7 allowing developers to define Touch areas on screen and mapped...Code for Rapid C# Windows Development eBook + LINQPad and Data Tools: LLBLGen LINQPad Data Context Driver Version 2.1: Sixth release of a LLBLGen Pro Typed Data Context Driver for LINQPad. For LLBLGen Pro versions 3.1 and 3.5(coming). New features:When you switch the query language to SQL, LINQPad updates the Schema Explorer to show SQL column names rather than CLR property names Connection dialog unloads assemblies when it has closed down so they are no longer locked - this allows them to be rebuilt while LINQPad is still open Connection dialog includes a button to quickly add assemblies needed for the...People's Note: People's Note 0.40: Version 0.40 adds an option to compact the database from the profile screen. Compacting a database can make it smaller and faster by removing empty spaces left over by editing, moving, and deleting notes. To install: copy the appropriate CAB file onto your WM device and run it.Microsoft All-In-One Code Framework - a centralized code sample library: C++, .NET Coding Guideline: Microsoft All-In-One Code Framework Coding Guideline This document describes the coding style guideline for native C++ and .NET (C# and VB.NET) programming used by the Microsoft All-In-One Code Framework project team.WebDAV for WHS: Version 1.0.67: - Added: Check whether the Remote Web Access is turned on or not; - Added: Check for Add-In updates;Image 3D Viewer: Image 3D Viewer: WPF .Net 3.5 .Net 4 .Net 4.5Phalanger - The PHP Language Compiler for the .NET Framework: 3.0 (March 2012) for .NET 4.0: March release of Phalanger 3.0 significantly enhances performance, adds new features and fixes many issues. See following for the list of main improvements: New features: Phalanger Tools installable for Visual Studio 2011 Beta "filter" extension with several most used filters implemented DomDocument HTML parser, loadHTML() method mail() PHP compatible function PHP 5.4 T_CALLABLE token PHP 5.4 "callable" type hint PCRE: UTF32 characters in range support configuration supports <c...Nearforums - ASP.NET MVC forum engine: Nearforums v8.0: Version 8.0 of Nearforums, the ASP.NET MVC Forum Engine, containing new features: Internationalization Custom authentication provider Access control list for forums and threads Webdeploy package checksum: abc62990189cf0d488ef915d4a55e4b14169bc01 Visit Roadmap for more details.BIDS Helper: BIDS Helper 1.6: This beta release is the first to support SQL Server 2012 (in addition to SQL Server 2005, 2008, and 2008 R2). Since it is marked as a beta release, we are looking for bug reports in the next few months as you use BIDS Helper on real projects. In addition to getting all existing BIDS Helper functionality working appropriately in SQL Server 2012 (SSDT), the following features are new... Analysis Services Tabular Smart Diff Tabular Actions Editor Tabular HideMemberIf Tabular Pre-Build ...Json.NET: Json.NET 4.5 Release 1: New feature - Windows 8 Metro build New feature - JsonTextReader automatically reads ISO strings as dates New feature - Added DateFormatHandling to control whether dates are written in the MS format or ISO format, with ISO as the default New feature - Added DateTimeZoneHandling to control reading and writing DateTime time zone details New feature - Added async serialize/deserialize methods to JsonConvert New feature - Added Path to JsonReader/JsonWriter/ErrorContext and exceptions w...SCCM Client Actions Tool: SCCM Client Actions Tool v1.11: SCCM Client Actions Tool v1.11 is the latest version. It comes with following changes since last version: Fixed a bug when ping and cmd.exe kept running in endless loop after action progress was finished. Fixed update checking from Codeplex RSS feed. The tool is downloadable as a ZIP file that contains four files: ClientActionsTool.hta – The tool itself. Cmdkey.exe – command line tool for managing cached credentials. This is needed for alternate credentials feature when running the HTA...WebSocket4Net: WebSocket4Net 0.5: Changes in this release fixed the wss's default port bug improved JsonWebSocket supported set client access policy protocol for silverlight fixed a handshake issue in Silverlight fixed a bug that "Host" field in handshake hadn't contained port if the port is not default supported passing in Origin parameter for handshaking supported reacting pings from server side fixed a bug in data sending fixed the bug sending a closing handshake with no message which would cause an excepti...SuperWebSocket, a .NET WebSocket Server: SuperWebSocket 0.5: Changes included in this release: supported closing handshake queue checking improved JSON subprotocol supported sending ping from server to client fixed a bug about sending a closing handshake with no message refactored the code to improve protocol compatibility fixed a bug about sub protocol configuration loading in Mono improved BasicSubProtocol added JsonWebSocketSessionSurvey™ - web survey & form engine: Survey™ 2.0: The new stable Survey™ Project 2.0.0.1 version contains many new features like: Technical changes: - Use of Jquery, ASTreeview, Tabs, Tooltips and new menuprovider Features & Bugfixes: Survey list and search function Folder structure for surveys New Menustructure Library list New Library fields User list and search functions Layout options for a survey with CSS, page header and footer New IP filter security feature Enhanced Token Management New Question fields as ID, Alias...Speed up Printer migration using PrintBrm and it's configuration files: BRMC.EXE: Run the tool from the extracted directory of the printbrm backup. You can use the following command to extract a backup file to a directory - PRINTBRM.EXE -R -D C:\TEMP\EXPAND -F C:\TEMP\PRINTERBACKUP.PRINTEREXPORTNew ProjectsAsp.NET Url Router: 1.Url rewritting. 2.Provider regex matcher 3.Support custom url validate handler.BC-Web: ch projectCape: Dynamically generates Capistrano recipes for Rake tasks.cstgamebgs: Project for wp7GCalculator: GCalculator for performing basic arithmetic operations. Windows Sidebar Gadget invacc: Invacc- for inventory and Account Onlineirgsh-node: Worker nodes of BlankOn Package Factory - http://irgsh.blankonlinux.or.id/irgsh-repo: Repository manager node of BlankOn Package Factory - http://irgsh.blankonlinux.or.id/irgsh-web: Web interface and task manager of BlankOn Package Factory - http://irgsh.blankonlinux.or.id/Kinect Explorer For SharePoint 2010: Kinect Explorer for SharePoint is a tool which provide Natural User Interface to browse through SharePoint sites. Use body gestures to browse, read, move, copy documents. Use Speech services to read-out the files.MCU: mcu devMVC3ShellCode: MVC3ShellCode MVC3ShellCode MVC3ShellCode MVC3ShellCode MVC3ShellCode MVC3ShellCode NetWatch: NetWatch - network watchdog Small application primary designed for network connectivity monitoring. You can configure set of network tests (ping, http, ...) and time plan for this tests. Application is running in windows notification area and notife you each problem. NMortgage: The goal of this project will be to give a prospective home buyer or an existing home owner the insight they need to explore effects of different repayment strategies or different mortgage structures. Nucleo.NET MVP: The Nucleo MVP framework provides a Model-View-Presenter approach that isn't obtrusive, can be utilized in multiple environments, and is versatile. Providing a lot of features you see in other frameworks, the Nucleo MVP framework provides many extensibility points, pretty much allowing you to rewrite most of the framework. It features dynamic injection support, presenter and view initializers (like what you see in ASP.NET MVC), model property injection, attribute- and convention-based vie...P2PShare: This project is to build a new and moden System for p2p file shearing supporting downloads from HTTP, HTTPS, FTP support for P2Pshare client list servers so files can point to a server or a host only file so no servers are used and only p2p is usedPipeLayer: proyecto de sistemas inteligentespython-irgsh: Python library for BlankOn Package Factory - http://irgsh.blankonlinux.or.id/RamGec XNA Controls - Window Elements Library for XNA Solutions: Lightweight, ultra-high performance and flexible library for displaying and managing Window Controls for XNA system. Features its own Window Designer for creating custom windows and controls.RPG Character Generators and Tools: Various tools for pen and paper style role playing games.Screen scraper: A program that can be used to download public domain MP3 and other media such as pdf documents.SharePoint Bdc request library: The given set of classes simplifies an access to the external data, which can be reached through BDC. The library allows to make simple requests for values from external data source, using a BDC Entity Instance Identifier(s) or a value of a certain BDC Entity field. Developed to interact with Business Data Connectivity of SharePoint 2010.testtom03232012git01: testtom03232012git01testtom03232012git02: testtom03232012git02the north star uc: University projectTyphon: Typhon is a role playing simulation management application, much like Nova, but written in MVC/C#.VRE LabTrove-SharePoint connector: The VRE LabTrove-SharePoint Connector provides a means of integrating the ability to view, post to, and edit posts stored in a LabTrove electronic laboratory notebook from within the familiar environment of Microsoft SharePoint. Once installed and configured, these Web Parts give SharePoint users a straightforward way to interact with any LabTrove installation that they wish to use. They also facilitate users to attach data that is stored in a SharePoint Document Library to the LabTrove posts...

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• HttpClient multithread performance

  - by pepper

  I have an application which downloads more than 4500 html pages from 62 target hosts using HttpClient (4.1.3 or 4.2-beta). It runs on Windows 7 64-bit. Processor - Core i7 2600K. Network bandwidth - 54 Mb/s. At this moment it uses such parameters: DefaultHttpClient and PoolingClientConnectionManager; Also it hasIdleConnectionMonitorThread from http://hc.apache.org/httpcomponents-client-ga/tutorial/html/connmgmt.html; Maximum total connections = 80; Default maximum connections per route = 5; For thread management it uses ForkJoinPool with the parallelism level = 5 (Do I understand correctly that it is a number of working threads?) In this case my network usage (in Windows task manager) does not rise above 2.5%. To download 4500 pages it takes 70 minutes. And in HttpClient logs I have such things: DEBUG ForkJoinPool-2-worker-1 [org.apache.http.impl.conn.PoolingClientConnectionManager]: Connection released: [id: 209][route: {}-http://stackoverflow.com][total kept alive: 6; route allocated: 1 of 5; total allocated: 10 of 80] Total allocated connections do not raise above 10-12, in spite of that I've set it up to 80 connections. If I'll try to rise parallelism level to 20 or 80, network usage remains the same but a lot connection time-outs will be generated. I've read tutorials on hc.apache.org (HttpClient Performance Optimization Guide and HttpClient Threading Guide) but they does not help. Task's code looks like this: public class ContentDownloader extends RecursiveAction { private final HttpClient httpClient; private final HttpContext context; private List<Entry> entries; public ContentDownloader(HttpClient httpClient, List<Entry> entries){ this.httpClient = httpClient; context = new BasicHttpContext(); this.entries = entries; } private void computeDirectly(Entry entry){ final HttpGet get = new HttpGet(entry.getLink()); try { HttpResponse response = httpClient.execute(get, context); int statusCode = response.getStatusLine().getStatusCode(); if ( (statusCode >= 400) && (statusCode <= 600) ) { logger.error("Couldn't get content from " + get.getURI().toString() + "\n" + response.toString()); } else { HttpEntity entity = response.getEntity(); if (entity != null) { String htmlContent = EntityUtils.toString(entity).trim(); entry.setHtml(htmlContent); EntityUtils.consumeQuietly(entity); } } } catch (Exception e) { } finally { get.releaseConnection(); } } @Override protected void compute() { if (entries.size() <= 1){ computeDirectly(entries.get(0)); return; } int split = entries.size() / 2; invokeAll(new ContentDownloader(httpClient, entries.subList(0, split)), new ContentDownloader(httpClient, entries.subList(split, entries.size()))); } } And the question is - what is the best practice to use multi threaded HttpClient, may be there is a some rules for setting up ConnectionManager and HttpClient? How can I use all of 80 connections and raise network usage? If necessary, I will provide more code.

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• Python Imaging: YCbCr problems

  - by daver

  Hi, I'm doing some image processing in Python using PIL, I need to extract the luminance layer from a series of images, and do some processing on that using numpy, then put the edited luminance layer back into the image and save it. The problem is, I can't seem to get any meaningful representation of my Image in a YCbCr format, or at least I don't understand what PIL is giving me in YCbCr. PIL documentation claims YCbCr format gives three channels, but when I grab the data out of the image using np.asarray, I get 4 channels. Ok, so I figure one must be alpha. Here is some code I'm using to test this process: import Image as im import numpy as np pengIm = im.open("Data\\Test\\Penguins.bmp") yIm = pengIm.convert("YCbCr") testIm = np.asarray(yIm) grey = testIm[:,:,0] grey = grey.astype('uint8') greyIm = im.fromarray(grey, "L") greyIm.save("Data\\Test\\grey.bmp") I'm expecting a greyscale version of my image, but what I get is this jumbled up mess: http://i.imgur.com/zlhIh.png Can anybody explain to me where I'm going wrong? The same code in matlab works exactly as I expect.

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• How to make .NET WebForm Routing work with Authorization

  - by jakmas

  I have routes that are being registered from the database into an asp.net website (non MVC). The routes register fine, they all work when I am logged in. What I am trying to do is create a landing page based on some route data: Page is [site]/landing/dell The route looks like: "landing/{client}" and it routes to my page Login.aspx, in there I get the client out of the route, then display some custom brand data based on the value. In my web.config, I have my authentication mode set to forms, with my loginUrl = "Login.aspx" When the user does not have the authorization cookie, it redirects the user to: [site]/Login.aspx?ReturnUrl=%2flanding%2fdell instead of keeping the route url, and displaying the correct data. The IIS server actually does not even process the route at all, just sends the user to the Login.aspx page. I have tried several additions to my web.config: etc, and many variations, but nothing seems to work. Ideas anyone? I assume this is a common issue, and it is just not well documented.

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• Get group key from bridge table

  - by Mads Jensen

  I'm developing an ETL process, and need a bridge table for a one-to-many relationship between a fact table and a dimension table (MySQL database). There is a limited number of combinations (some thousands), so I want to re-use group keys from the bridge table to to limit the size. Any group of dimensions belonging to a fact row will consist of a number of dimension keys (1 to around 15), assigned to a unique group key, as below: group_key | dimension_key ----------------------- 1 | 1 1 | 3 1 | 4 2 | 1 2 | 2 2 | 3 3 | 1 3 | 4 How do I go about retrieving the unique group key for the dimensions 1,3,4 (ie. 1).

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• malloc()/free() behavior differs between Debian and Redhat

  - by StasM

  I have a Linux app (written in C) that allocates large amount of memory (~60M) in small chunks through malloc() and then frees it (the app continues to run then). This memory is not returned to the OS but stays allocated to the process. Now, the interesting thing here is that this behavior happens only on RedHat Linux and clones (Fedora, Centos, etc.) while on Debian systems the memory is returned back to the OS after all freeing is done. Any ideas why there could be the difference between the two or which setting may control it, etc.?

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• How to call an external webservice in asp.net

  - by prince23

  hi, i have an webservice written by java application now. i need to use that webservice in my application and send a parameter to it. For example lets say this is the path of the webservice : http://localhost:1838/Ajax/WebService.as now once i click the button in my page[emp.aspx] i need to call the above webservice path 2: what is the use of creating an proxy for an webservice using wsdl tool can anyone tell me the syntax for it? so what is the process i need to follow to consume an webservice written in another applcation or domain looking forward for an solution thank you

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• Detecting/Repairing NSConnection failure

  - by anthony

  I would like to use NSConnection/NSDistributedObject for interprocess communication. I would like the client to be able to handle the case where the server is only occasionally reachable. How can I determine if sending a message to the NSConnection will fail or has failed? Currently if my server (the process that has vended the remote object) dies, the client will crash if it sends a selector to the remote object. Ideally I'd like to have a wrapper for the remote object that can lazily instantiate (or reinstantiate) the connection, and return a default value in the case where the connection could not be instantiated, or the connection has failed. I don't really know the correct way to do this using objective c. Here's some pseudocode representing this logic: if myConnection is null: instantiate myConnection if MyConnection is null: return defaultValue try return [myConnection someMethod] catch myConnection = null return defaultValue

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• Kill a Perl system call after a timeout

  - by Fergal

  I've got a Perl script I'm using for running a file processing tool which is started using backticks. The problem is that occasionally the tool hangs and It needs to be killed in order for the rest of the files to be processed. Whats the best way best way to apply a timeout after which the parent script will kill the hung process? At the moment I'm using: foreach $file (@FILES) { $runResult = `mytool $file >> $file.log`; } But when mytool hangs after n seconds I'd like to be able to kill it and continue to the next file.

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• MVC3 Razor DropDownListFor Enums

  - by jordan.baucke

  Trying to get my project updated to MVC3, something I just can't find: I have a simple datatype of ENUMS: public enum States() { AL,AK,AZ,...WY } Which I want to use as a DropDown/SelectList in my view of a model that contains this datatype: public class FormModel() { public States State {get; set;} } Pretty straight forward: when I go to use the auto-generate view for this partial class, it ignores this type. I need a simple select list that sets the value of the enum as the selected item when I hit submit and process via my AJAX - JSON POST Method. And than the view (???!): <div class="editor-field"> @Html.DropDownListFor(model => model.State, model => model.States) </div> thanks in advance for the advice!

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• .NET Code Evolution

  - by Alois Kraus

  Originally posted on: http://geekswithblogs.net/akraus1/archive/2013/07/24/153504.aspxAt my day job I do look at a lot of code written by other people. Most of the code is quite good and some is even a masterpiece. And there is also code which makes you think WTF… oh it was written by me. Hm not so bad after all. There are many excuses reasons for bad code. Most often it is time pressure followed by not enough ambition (who cares) or insufficient training. Normally I do care about code quality quite a lot which makes me a (perceived) slow worker who does write many tests and refines the code quite a lot because of the design deficiencies. Most of the deficiencies I do find by putting my design under stress while checking for invariants. It does also help a lot to step into the code with a debugger (sometimes also Windbg). I do this much more often when my tests are red. That way I do get a much better understanding what my code really does and not what I think it should be doing. This time I do want to show you how code can evolve over the years with different .NET Framework versions. Once there was  time where .NET 1.1 was new and many C++ programmers did switch over to get rid of not initialized pointers and memory leaks. There were also nice new data structures available such as the Hashtable which is fast lookup table with O(1) time complexity. All was good and much code was written since then. At 2005 a new version of the .NET Framework did arrive which did bring many new things like generics and new data structures. The “old” fashioned way of Hashtable were coming to an end and everyone used the new Dictionary<xx,xx> type instead which was type safe and faster because the object to type conversion (aka boxing) was no longer necessary. I think 95% of all Hashtables and dictionaries use string as key. Often it is convenient to ignore casing to make it easy to look up values which the user did enter. An often followed route is to convert the string to upper case before putting it into the Hashtable. Hashtable Table = new Hashtable(); void Add(string key, string value) { Table.Add(key.ToUpper(), value); } This is valid and working code but it has problems. First we can pass to the Hashtable a custom IEqualityComparer to do the string matching case insensitive. Second we can switch over to the now also old Dictionary type to become a little faster and we can keep the the original keys (not upper cased) in the dictionary. Dictionary<string, string> DictTable = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase); void AddDict(string key, string value) { DictTable.Add(key, value); } Many people do not user the other ctors of Dictionary because they do shy away from the overhead of writing their own comparer. They do not know that .NET has for strings already predefined comparers at hand which you can directly use. Today in the many core area we do use threads all over the place. Sometimes things break in subtle ways but most of the time it is sufficient to place a lock around the offender. Threading has become so mainstream that it may sound weird that in the year 2000 some guy got a huge incentive for the idea to reduce the time to process calibration data from 12 hours to 6 hours by using two threads on a dual core machine. Threading does make it easy to become faster at the expense of correctness. Correct and scalable multithreading can be arbitrarily hard to achieve depending on the problem you are trying to solve. Lets suppose we want to process millions of items with two threads and count the processed items processed by all threads. A typical beginners code might look like this: int Counter; void IJustLearnedToUseThreads() { var t1 = new Thread(ThreadWorkMethod); t1.Start(); var t2 = new Thread(ThreadWorkMethod); t2.Start(); t1.Join(); t2.Join(); if (Counter != 2 * Increments) throw new Exception("Hmm " + Counter + " != " + 2 * Increments); } const int Increments = 10 * 1000 * 1000; void ThreadWorkMethod() { for (int i = 0; i < Increments; i++) { Counter++; } } It does throw an exception with the message e.g. “Hmm 10.222.287 != 20.000.000” and does never finish. The code does fail because the assumption that Counter++ is an atomic operation is wrong. The ++ operator is just a shortcut for Counter = Counter + 1 This does involve reading the counter from a memory location into the CPU, incrementing value on the CPU and writing the new value back to the memory location. When we do look at the generated assembly code we will see only inc dword ptr [ecx+10h] which is only one instruction. Yes it is one instruction but it is not atomic. All modern CPUs have several layers of caches (L1,L2,L3) which try to hide the fact how slow actual main memory accesses are. Since cache is just another word for redundant copy it can happen that one CPU does read a value from main memory into the cache, modifies it and write it back to the main memory. The problem is that at least the L1 cache is not shared between CPUs so it can happen that one CPU does make changes to values which did change in meantime in the main memory. From the exception you can see we did increment the value 20 million times but half of the changes were lost because we did overwrite the already changed value from the other thread. This is a very common case and people do learn to protect their  data with proper locking.   void Intermediate() { var time = Stopwatch.StartNew(); Action acc = ThreadWorkMethod_Intermediate; var ar1 = acc.BeginInvoke(null, null); var ar2 = acc.BeginInvoke(null, null); ar1.AsyncWaitHandle.WaitOne(); ar2.AsyncWaitHandle.WaitOne(); if (Counter != 2 * Increments) throw new Exception(String.Format("Hmm {0:N0} != {1:N0}", Counter, 2 * Increments)); Console.WriteLine("Intermediate did take: {0:F1}s", time.Elapsed.TotalSeconds); } void ThreadWorkMethod_Intermediate() { for (int i = 0; i < Increments; i++) { lock (this) { Counter++; } } } This is better and does use the .NET Threadpool to get rid of manual thread management. It does give the expected result but it can result in deadlocks because you do lock on this. This is in general a bad idea since it can lead to deadlocks when other threads use your class instance as lock object. It is therefore recommended to create a private object as lock object to ensure that nobody else can lock your lock object. When you read more about threading you will read about lock free algorithms. They are nice and can improve performance quite a lot but you need to pay close attention to the CLR memory model. It does make quite weak guarantees in general but it can still work because your CPU architecture does give you more invariants than the CLR memory model. For a simple counter there is an easy lock free alternative present with the Interlocked class in .NET. As a general rule you should not try to write lock free algos since most likely you will fail to get it right on all CPU architectures. void Experienced() { var time = Stopwatch.StartNew(); Task t1 = Task.Factory.StartNew(ThreadWorkMethod_Experienced); Task t2 = Task.Factory.StartNew(ThreadWorkMethod_Experienced); t1.Wait(); t2.Wait(); if (Counter != 2 * Increments) throw new Exception(String.Format("Hmm {0:N0} != {1:N0}", Counter, 2 * Increments)); Console.WriteLine("Experienced did take: {0:F1}s", time.Elapsed.TotalSeconds); } void ThreadWorkMethod_Experienced() { for (int i = 0; i < Increments; i++) { Interlocked.Increment(ref Counter); } } Since time does move forward we do not use threads explicitly anymore but the much nicer Task abstraction which was introduced with .NET 4 at 2010. It is educational to look at the generated assembly code. The Interlocked.Increment method must be called which does wondrous things right? Lets see: lock inc dword ptr [eax] The first thing to note that there is no method call at all. Why? Because the JIT compiler does know very well about CPU intrinsic functions. Atomic operations which do lock the memory bus to prevent other processors to read stale values are such things. Second: This is the same increment call prefixed with a lock instruction. The only reason for the existence of the Interlocked class is that the JIT compiler can compile it to the matching CPU intrinsic functions which can not only increment by one but can also do an add, exchange and a combined compare and exchange operation. But be warned that the correct usage of its methods can be tricky. If you try to be clever and look a the generated IL code and try to reason about its efficiency you will fail. Only the generated machine code counts. Is this the best code we can write? Perhaps. It is nice and clean. But can we make it any faster? Lets see how good we are doing currently. Level Time in s IJustLearnedToUseThreads Flawed Code Intermediate 1,5 (lock) Experienced 0,3 (Interlocked.Increment) Master 0,1 (1,0 for int[2]) That lock free thing is really a nice thing. But if you read more about CPU cache, cache coherency, false sharing you can do even better. int[] Counters = new int[12]; // Cache line size is 64 bytes on my machine with an 8 way associative cache try for yourself e.g. 64 on more modern CPUs void Master() { var time = Stopwatch.StartNew(); Task t1 = Task.Factory.StartNew(ThreadWorkMethod_Master, 0); Task t2 = Task.Factory.StartNew(ThreadWorkMethod_Master, Counters.Length - 1); t1.Wait(); t2.Wait(); Counter = Counters[0] + Counters[Counters.Length - 1]; if (Counter != 2 * Increments) throw new Exception(String.Format("Hmm {0:N0} != {1:N0}", Counter, 2 * Increments)); Console.WriteLine("Master did take: {0:F1}s", time.Elapsed.TotalSeconds); } void ThreadWorkMethod_Master(object number) { int index = (int) number; for (int i = 0; i < Increments; i++) { Counters[index]++; } } The key insight here is to use for each core its own value. But if you simply use simply an integer array of two items, one for each core and add the items at the end you will be much slower than the lock free version (factor 3). Each CPU core has its own cache line size which is something in the range of 16-256 bytes. When you do access a value from one location the CPU does not only fetch one value from main memory but a complete cache line (e.g. 16 bytes). This means that you do not pay for the next 15 bytes when you access them. This can lead to dramatic performance improvements and non obvious code which is faster although it does have many more memory reads than another algorithm. So what have we done here? We have started with correct code but it was lacking knowledge how to use the .NET Base Class Libraries optimally. Then we did try to get fancy and used threads for the first time and failed. Our next try was better but it still had non obvious issues (lock object exposed to the outside). Knowledge has increased further and we have found a lock free version of our counter which is a nice and clean way which is a perfectly valid solution. The last example is only here to show you how you can get most out of threading by paying close attention to your used data structures and CPU cache coherency. Although we are working in a virtual execution environment in a high level language with automatic memory management it does pay off to know the details down to the assembly level. Only if you continue to learn and to dig deeper you can come up with solutions no one else was even considering. I have studied particle physics which does help at the digging deeper part. Have you ever tried to solve Quantum Chromodynamics equations? Compared to that the rest must be easy ;-). Although I am no longer working in the Science field I take pride in discovering non obvious things. This can be a very hard to find bug or a new way to restructure data to make something 10 times faster. Now I need to get some sleep ….

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• What is your favourite Windbg tip/trick?

  - by user15071

  I have come to realize that Windbg is a very powerful debugger for the Windows platform & I learn something new about it once in a while. Can fellow Windbg users share some of their mad skills? ps: I am not looking for a nifty command, those can be found in the documentation. How about sharing tips on doing something that one couldn't otherwise imagine could be done with windbg? e.g. Some way to generate statistics about memory allocations when a process is run under windbg.

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• Ad/Banner Management/Rotation for Ruby on Rails?

  - by David N. Welton

  Hi, I have a niche site that I'd like to sell banners for directly, rather than going through adsense. I need a system to manage the whole process: displaying ads and an administrative interface to manage them. It doesn't have to be anything terribly fancy, although open source is greatly preferred so that I can grow the system as needs be. Since the site itself is in Rails, I would prefer something for that environment. Googling turns up bunches of them in PHP, but the results are a bit polluted and I didn't have any luck finding one that was done in/for Rails. If I don't find one, I suppose I'll see what I can do to hack together something and release it myself under an open license. Another possibility is this: http://www.google.com/admanager - anyone have anything to say about it? Is it right for someone just selling a few ads for a not-so-big site? Thanks, Dave

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• Debugging ASP.NET on a built-in web server suddenly stops

  - by Anton Gogolev

  I have Windows Server 2008 (64-bit), VS 2008 with its built-in webserver and an ASP.NET MVC 1.0 webapp. All I'm trying to do is to debug said app. I have a bunch of breakpoints, but they behave in a very strange way. When I fist start a debugging session with F5 and hit a breakpoint, the debugger stops just fine. However, after serveral F10s/F11s debugging suddenly "stops" (no exceptions at that time), but neither VS detaches from browsers' process, nor webapp execution stops: Visual Studio stays attached, and web request continues executing as usual. I tried various browsers (Chrome, Firefox, IE), but to no avail. What do I do to solve this? It really drives me insane.

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• Error in MySQL Workbench Forward Engineered Stored Procedures

  - by colithium

  I am using MySQL Workbench (5.1.18 OSS rev 4456) to forward engineer a SQL CREATE script. For every stored procedure, the automatic process outputs something like: DELIMITER // USE DB_Name// DB_Name// DROP procedure IF EXISTS `DB_Name`.`SP_Name` // USE DB_Name// DB_Name// CREATE PROCEDURE `DB_Name`.`SP_Name` (id INT) BEGIN SELECT * FROM Table_Name WHERE Id = id; END// The two lines that are simply the database name followed by the delimiter are errors and are reported as such when running the script. As long as they are ignored, it looks like everything gets created just fine. But why would it add those lines? I am creating the database in the WAMP environment which uses MySQL 5.1.36

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• Access Database Connection

  - by Gerory

  I am using C#.net application with oledbConnection to open database in exclusive mode what exactly process in backend when we open database in exclusive mode , it not increse size of database compare to shared mode connectivity. Is it doing Compat or Repair when it close connection of Exclusive Mode?? As we are facing unExpected Errors at time of open connection using Exclusive mode & its come abnormally even we have dispossed all connection properly. Please share ur view ...if it doing compact/reapai at time of closing connection is there a way to wait before opening new Connection?

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• Initiate a PHP class where class name is a variable

  - by ed209

  I need some help with an error I have not encountered before and can't seem to find anywhere. In a PHP mvc framework (just from a tutorial) I have the following: // Initiate the class $className = 'Controller_' . ucfirst($controller); if (class_exists($className)) { $controller = new $className($this->registry); } $className is showing the correct class name (case is also correct). But when I run it I get this in the apache error log (no php error) [Wed Mar 31 10:34:12 2010] [notice] child pid 987 exit signal Segmentation fault (11) Process id is different on every call. I am running PHP 5.3.0 on os x 10.6. This site seems to work on 5.2.11 on another Mac. Not really sure where to go next to debug it. I guess it could be an apache setting as much as a php bug or a problem with the code... any suggestions on where to look next?

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• Does Amazon S3's HTTP Uploads feature support web-hook style callbacks?

  - by Gabe Hollombe

  When uploading files to Amazon S3 using the browser http upload feature, I know I can specify a success_action_redirect field/value that will tell my browser where to go when the upload is done. I'm wondering: is it possible to ask Amazon to make a web hook style POST request to my web server whenever a file gets uploaded? Basically, I want a way of being notified whenever a client uploads a new file, so that my server can process the upload. I'd like to do this without relying on the client to make the request to my server to tell me the file has been uploaded (never trust the client, right?).

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• ShellExecute not working from IDE but works otherwise.

  - by Altar

  I want to create and then open a txt file using the ShellExecute command. I have used this code for years with Delphi 7 and it worked: function Executa(CONST ExeName, Parameters: string): Boolean; begin if Parameters= '' then Result:= ShellExecute(0, 'open', PChar(ExeName), NIL , nil, SW_SHOWNORMAL)> 32 else Result:= ShellExecute(0, 'open', PChar(ExeName), PChar(Parameters), nil, SW_SHOWNORMAL)> 32; end; Now, I switch to Windows 7 (don't like it; they stuck it on my throat with my new laptop) 64 bit and the code is not working anymore when it runs from IDE. Delhi shows the CPU window with the caption "CPU-Process unknown (2352)". I close the CU windows and everything works fine until I close the application, when Delphi shows the CPU window one more time. If I run the app from outside IDE, it works fine. Looks like the debugger has something to say to me, but I don't know what.

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• Watching setTimeout loops so that only one is running at a time.

  - by DA

  I'm creating a content rotator in jQuery. 5 items total. Item 1 fades in, pauses 10 seconds, fades out, then item 2 fades in. Repeat. Simple enough. Using setTimeout I can call a set of functions that create a loop and will repeat the process indefinitely. I now want to add the ability to interrupt this rotator at any time by clicking on a navigation element to jump directly to one of the content items. I originally started going down the path of pinging a variable constantly (say every half second) that would check to see if a navigation element was clicked and, if so, abandon the loop, then restart the loop based on the item that was clicked. The challenge I ran into was how to actually ping a variable via a timer. The solution is to dive into JavaScript closures...which are a little over my head but definitely something I need to delve into more. However, in the process of that, I came up with an alternative option that actually seems to be better performance-wise (theoretically, at least). I have a sample running here: http://jsbin.com/uxupi/14 (It's using console.log so have fireBug running) Sample script: $(document).ready(function(){ var loopCount = 0; $('p#hello').click(function(){ loopCount++; doThatThing(loopCount); }) function doThatOtherThing(currentLoopCount) { console.log('doThatOtherThing-'+currentLoopCount); if(currentLoopCount==loopCount){ setTimeout(function(){doThatThing(currentLoopCount)},5000) } } function doThatThing(currentLoopCount) { console.log('doThatThing-'+currentLoopCount); if(currentLoopCount==loopCount){ setTimeout(function(){doThatOtherThing(currentLoopCount)},5000); } } }) The logic being that every click of the trigger element will kick off the loop passing into itself a variable equal to the current value of the global variable. That variable gets passed back and forth between the functions in the loop. Each click of the trigger also increments the global variable so that subsequent calls of the loop have a unique local variable. Then, within the loop, before the next step of each loop is called, it checks to see if the variable it has still matches the global variable. If not, it knows that a new loop has already been activated so it just ends the existing loop. Thoughts on this? Valid solution? Better options? Caveats? Dangers? UPDATE: I'm using John's suggestion below via the clearTimeout option. However, I can't quite get it to work. The logic is as such: var slideNumber = 0; var timeout = null; function startLoop(slideNumber) { ...do stuff here to set up the slide based on slideNumber... slideFadeIn() } function continueCheck(){ if (timeout != null) { // cancel the scheduled task. clearTimeout(timeout); timeout = null; return false; }else{ return true; } }; function slideFadeIn() { if (continueCheck){ // a new loop hasn't been called yet so proceed... // fade in the LI $currentListItem.fadeIn(fade, function() { if(multipleFeatures){ timeout = setTimeout(slideFadeOut,display); } }); }; function slideFadeOut() { if (continueLoop){ // a new loop hasn't been called yet so proceed... slideNumber=slideNumber+1; if(slideNumber==features.length) { slideNumber = 0; }; timeout = setTimeout(function(){startLoop(slideNumber)},100); }; startLoop(slideNumber); The above kicks of the looping. I then have navigation items that, when clicked, I want the above loop to stop, then restart with a new beginning slide: $(myNav).click(function(){ clearTimeout(timeout); timeout = null; startLoop(thisItem); }) If I comment out 'startLoop...' from the click event, it, indeed, stops the initial loop. However, if I leave that last line in, it doesn't actually stop the initial loop. Why? What happens is that both loops seem to run in parallel for a period. So, when I click my navigation, clearTimeout is called, which clears it.

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• Django multiple generic_inline_formset in a view

  - by Can Burak Cilingir

  We have a bunch of formsets: EmailAddressInlineFormSet = generic_inlineformset_factory( EmailAddress, extra=1, exclude=["created_by","last_modified_by"]) emailaddressformset = EmailAddressInlineFormSet( instance=person, prefix="emailaddress") # [ more definitions ] and, in the view, we process them as: emailaddressformset = EmailAddressInlineFormSet( request.POST, instance=person, prefix="emailaddress") # [ more definitions ] So, nothing fancy or unordinary. The unfortunate or unordinary fact is, we have 15 of these formsets, one for email addresses, other for phone numbers etc. so the view code is ugly and not-so-manageable. What would be the most unhackish way to handle this number of formsets in a single view? At the end -i guess- I'm looking for a class or a functionality like multiple_generic_inline_formset and open to all kind of suggestions or discussions.

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• What is the best possible technology for pulling huge data from 4 remote servers

  - by Habib Ullah Bahar

  Hello, For one of our project, we need to pull huge real time stock data from 4 remote servers across two countries. The trivial process here, check the sources for a regular interval and save the update to database. But as these are real time stock data of more than 1000 companies, I have to pull every second, which isn't good in case of memory, bandwidth I think. Please give me suggestion on which technology/platform [We are flexible here. PHP, Python, Java, PERL - anyone of them will be OK for us] we should choose, it can be achieved easily and with better performance.

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