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• Queuing methods to be run on an object by different threads in Python

  - by Ben

  Let's say I have an object who's class definition looks like: class Command: foo = 5 def run(self, bar): time.sleep(1) self.foo = bar return self.foo If this class is instantiated once, but different threads are hitting its run method (via an HTTP request, handled separately) passing in different args, what is the best method to queue them? Can this be done in the class definition itself?

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• Is there a limit on the number of mutex objects that can be created in a Windows process?

  - by young-phillip

  I'm writing a c# application that can create a series of request messages. Each message could have a response, that needs to be waited on by a consumer. Where the number of outstanding request messages is constrained, I have used the windows EVENT to solve this problem. However, I know there is a limit on how many EVENT objects can be created in a single process, and in this instance, its possible I might exceed that limit. Does anyone know if there is a similar limit on creation of mutex objects or semaphores? I know this can be solved by some sort of pool of shared resources, that are grabbed by consumers when they need to wait, but it would be more convenient if each request message could have its own sync object.

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• Python: Script works, but seems to deadlock after some time

  - by sberry2A

  I have the following script, which is working for the most part Link to PasteBin The script's job is to start a number of threads which in turn each start a subprocess with Popen. The output from each subprocess is as follows: 1 2 3 . . . n Done Bascially the subprocess is transferring 10M records from tables in one database to different tables in another db with a lot of data massaging/manipulation in between because of the different schemas. If the subprocess fails at any time in it's execution (bad records, duplicate primary keys, etc), or it completes successfully, it will output "Done\n". If there are no more records to select against for transfer then it will output "NO DATA\n" My intent was to create my script "tableTransfer.py" which would spawn a number of these processes, read their output, and in turn output information such as number of updates completed, time remaining, time elapsed, and number of transfers per second. I started running the process last night and checked in this morning to see it had deadlocked. There were not subprocceses running, there are still records to be updated, and the script had not exited. It was simply sitting there, no longer outputting the current information because no subprocces were running to update the total number complete which is what controls updates to the output. This is running on OS X. I am looking for three things: I would like to get rid of the possibility of this deadlock occurring so I don't need to check in on it as frequently. Is there some issue with locking? Am I doing this in a bad way (gThreading variable to control looping of spawning additional thread... etc.) I would appreciate some suggestions for improving my overall methodology. How should I handle ctrl-c exit? Right now I need to kill the process, but assume I should be able to use the signal module or other to catch the signal and kill the threads, is that right? I am not sure whether I should be pasting my entire script here, since I usually just paste snippets. Let me know if I should paste it here as well.

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• In app purchase on iphone.: How to receive your available products *before* someone may be able to b

  - by Thorsten S.

  Currently I am loading my supported products from a plist and after that I send a SKProductsRequest to guarantee that my SKProducts are still valid. So I set up the request, start it and get the response in: (void)productsRequest:(SKProductsRequest *)request didReceiveResponse:(SKProductsResponse *)response Now, so far all functions correctly. Problem: From calling the request until receiving the response it may last several seconds. Until that my app is already loaded and the user may be able to choose and buy a product. But because no products have been received, the available products are not in sync with the validated products - unlikely, but possible error. So my idea is to wait until the data is loaded and only continue when the list is validated. (Just a few seconds waiting...). I have a singleton instance managing all products. + (MyClass *) sharedInstance { if (!sharedInstance) sharedInstance = [MyClass new]; // Now wait until we have our data [condition lock]; while (noEntriesYet) // is yes at begin [condition wait]; [condition unlock]; return sharedInstance; } - productsRequest: didReceiveResponse: { [condition lock]; // I have my data noEntriesYet = false; [condition signal]; [condition unlock]; } Problem: The app freezes. Everything works fine if didReceiveResponse is completed before the sharedInstance is queried. There are different threads, the lock is working if wait is reached during didReceiveResponse, everything fine. But if not, didReceiveResponse is never called even if the request was sent. The lock is released, everything looks ok. I have tried to send the product request in a separate NSThread, with NSOperationQueue...without avail. Why ? What is happening ? How to solve the problem ?

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• ASP.NET Exception Handling in background threads

  - by Xodarap

  When I do ThreadPool.QueueUserWorkItem, I don't want unhandled exceptions to kill my entire process. So I do something like: ThreadPool.QueueUserWorkItem(delegate() { try { FunctionIActuallyWantToCall(); } catch { HandleException(); } }); Is this the recommended pattern? It seems like there should be a simpler way to do this. It's in an asp.net-mvc app, if that's relevant.

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• Out-Of-Memory while doing Core Data migration

  - by Kamchatka

  Hello, I'm migrating a CoreData model between two versions of an application. I was storing binary data as blobs in the previous version and I want to take them out of the blobs for performance. My issue is that during the migration it seems that Core Data loads everything into memory which leads to Low Memory Warnings and then to my app being killed. Apple documentation suggests the following : http://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/CoreDataVersioning/Articles/vmCustomizingTheProcess.html#//apple_ref/doc/uid/TP40005510-SW9 However, it seems to rely on the fact that the large objects are applied different mapping. In my case, all the objects are basically the same and the same mapping has to be applied to each of them. I don't see in this case how I could apply their technique. How should I handle a migration with very large objects ?

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• Heavy weight and light weight thread

  - by rocker

  What are the Light weight and heavy weight threads in terms of java????

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• C# Process Binary File, Multi-Thread Processing

  - by washtik

  I have the following code that processes a binary file. I want to split the processing workload by using threads and assigning each line of the binary file to threads in the ThreadPool. Processing time for each line is only small but when dealing with files that might contain hundreds of lines, it makes sense to split the workload. My question is regarding the BinaryReader and thread safety. First of all, is what I am doing below acceptable. I have a feeling it would be better to pass only the binary for each line to the PROCESS_Binary_Return_lineData method. Please note the code below is conceptual. I looking for a but of guidance on this as my knowledge of multi-threading is in its infancy. Perhaps there is a better way to achieve the same result, i.e. split processing of each binary line. var dic = new Dictionary<DateTime, Data>(); var resetEvent = new ManualResetEvent(false); using (var b = new BinaryReader(File.Open(Constants.dataFile, FileMode.Open, FileAccess.Read, FileShare.Read))) { var lByte = b.BaseStream.Length; var toProcess = 0; while (lByte >= DATALENGTH) { b.BaseStream.Position = lByte; lByte = lByte - AB_DATALENGTH; ThreadPool.QueueUserWorkItem(delegate { Interlocked.Increment(ref toProcess); var lineData = PROCESS_Binary_Return_lineData(b); lock(dic) { if (!dic.ContainsKey(lineData.DateTime)) { dic.Add(lineData.DateTime, lineData); } } if (Interlocked.Decrement(ref toProcess) == 0) resetEvent.Set(); }, null); } } resetEvent.WaitOne();

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• How to correctly stop thread which is using Control.Invoke

  - by codymanix

  I tried the following (pseudocode) but I always get a deadlock when Iam trying to stop my thread. The problem is that Join() waits for the thread to complete and a pending Invoke() operation is also waiting to complete. How can I solve this? Thread workerThread = new Thread(BackupThreadRunner); volatile bool cancel; // this is the thread worker routine void BackupThreadRunner() { while (!cancel) { DoStuff(); ReportProgress(); } } // main thread void ReportProgress() { if (InvokeRequired) { Invoke(ReportProgress); } UpdateStatusBarAndStuff(); } // main thread void DoCancel() { cancel=true; workerThread.Join(); }

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• Message queue proxy in Python + Twisted

  - by gasper_k

  Hi, I want to implement a lightweight Message Queue proxy. It's job is to receive messages from a web application (PHP) and send them to the Message Queue server asynchronously. The reason for this proxy is that the MQ isn't always avaliable and is sometimes lagging, or even down, but I want to make sure the messages are delivered, and the web application returns immediately. So, PHP would send the message to the MQ proxy running on the same host. That proxy would save the messages to SQLite for persistence, in case of crashes. At the same time it would send the messages from SQLite to the MQ in batches when the connection is available, and delete them from SQLite. Now, the way I understand, there are these components in this service: message listener (listens to the messages from PHP and writes them to a Incoming Queue) DB flusher (reads messages from the Incoming Queue and saves them to a database; due to SQLite single-threadedness) MQ connection handler (keeps the connection to the MQ server online by reconnecting) message sender (collects messages from SQlite db and sends them to the MQ server, then removes them from db) I was thinking of using Twisted for #1 (TCPServer), but I'm having problem with integrating it with other points, which aren't event-driven. Intuition tells me that each of these points should be running in a separate thread, because all are IO-bound and independent of each other, but I could easily put them in a single thread. Even though, I couldn't find any good and clear (to me) examples on how to implement this worker thread aside of Twisted's main loop. The example I've started with is the chatserver.py, which uses service.Application and internet.TCPServer objects. If I start my own thread prior to creating TCPServer service, it runs a few times, but the it stops and never runs again. I'm not sure, why this is happening, but it's probably because I don't use threads with Twisted correctly. Any suggestions on how to implement a separate worker thread and keep Twisted? Do you have any alternative architectures in mind?

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• Python C API from C++ app - know when to lock

  - by Alex

  Hi Everyone, I am trying to write a C++ class that calls Python methods of a class that does some I/O operations (file, stdout) at once. The problem I have ran into is that my class is called from different threads: sometimes main thread, sometimes different others. Obviously I tried to apply the approach for Python calls in multi-threaded native applications. Basically everything starts from PyEval_AcquireLock and PyEval_ReleaseLock or just global locks. According to the documentation here when a thread is already locked a deadlock ensues. When my class is called from the main thread or other one that blocks Python execution I have a deadlock. Python Cfunc1() - C++ func that creates threads internally which lead to calls in "my class", It stuck on PyEval_AcquireLock, obviously the Python is already locked, i.e. waiting for C++ Cfunc1 call to complete... It completes fine if I omit those locks. Also it completes fine when Python interpreter is ready for the next user command, i.e. when thread is calling funcs in the background - not inside of a native call I am looking for a workaround. I need to distinguish whether or not the global lock is allowed, i.e. Python is not locked and ready to receive the next command... I tried PyGIL_Ensure, unfortunately I see hang. Any known API or solution for this ? (Python 2.4)

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• Will creating a background thread in a WCF service during a call, take up a thread in the ASP .NET t

  - by Nate Pinchot

  The following code is part of a WCF service. Will eventWatcher take up a thread in the ASP .NET thread pool, even if it is set IsBackground = true? /// <summary> /// Provides methods to work with the PhoneSystem web services SDK. /// This is a singleton since we need to keep track of what lines (extensions) are open. /// </summary> public sealed class PhoneSystemWebServiceFactory : IDisposable { // singleton instance reference private static readonly PhoneSystemWebServiceFactory instance = new PhoneSystemWebServiceFactory(); private static readonly object l = new object(); private static volatile Hashtable monitoredExtensions = new Hashtable(); private static readonly PhoneSystemWebServiceClient webServiceClient = CreateWebServiceClient(); private static volatile bool isClientRegistered; private static volatile string clientHandle; private static readonly Thread eventWatcherThread = new Thread(EventPoller) {IsBackground = true}; #region Constructor // these constructors are hacks to make the C# compiler not mark beforefieldinit // more info: http://www.yoda.arachsys.com/csharp/singleton.html static PhoneSystemWebServiceFactory() { } PhoneSystemWebServiceFactory() { } #endregion #region Properties /// <summary> /// Gets a thread safe instance of PhoneSystemWebServiceFactory /// </summary> public static PhoneSystemWebServiceFactory Instance { get { return instance; } } #endregion #region Private methods /// <summary> /// Create and configure a PhoneSystemWebServiceClient with basic http binding and endpoint from app settings. /// </summary> /// <returns>PhoneSystemWebServiceClient</returns> private static PhoneSystemWebServiceClient CreateWebServiceClient() { string url = ConfigurationManager.AppSettings["PhoneSystemWebService_Url"]; if (string.IsNullOrEmpty(url)) { throw new ConfigurationErrorsException( "The AppSetting \"PhoneSystemWebService_Url\" could not be found. Check the application configuration and ensure that the element exists. Example: <appSettings><add key=\"PhoneSystemWebService_Url\" value=\"http://xyz\" /></appSettings>"); } return new PhoneSystemWebServiceClient(new BasicHttpBinding(), new EndpointAddress(url)); } #endregion #region Event poller public static void EventPoller() { while (true) { if (Thread.CurrentThread.ThreadState == ThreadState.Aborted || Thread.CurrentThread.ThreadState == ThreadState.AbortRequested || Thread.CurrentThread.ThreadState == ThreadState.Stopped || Thread.CurrentThread.ThreadState == ThreadState.StopRequested) break; // get events //webServiceClient.GetEvents(clientHandle, 30, 100); } Thread.Sleep(5000); } #endregion #region Client registration methods private static void RegisterClientIfNeeded() { if (isClientRegistered) { return; } lock (l) { // double lock check if (isClientRegistered) { return; } //clientHandle = webServiceClient.RegisterClient("PhoneSystemWebServiceFactoryInternal", null); isClientRegistered = true; } } private static void UnregisterClient() { if (!isClientRegistered) { return; } lock (l) { // double lock check if (!isClientRegistered) { return; } //webServiceClient.UnegisterClient(clientHandle); } } #endregion #region Phone extension methods public bool SubscribeToEventsForExtension(string extension) { if (monitoredExtensions.Contains(extension)) { return false; } lock (monitoredExtensions.SyncRoot) { // double lock check if (monitoredExtensions.Contains(extension)) { return false; } RegisterClientIfNeeded(); // open line so we receive events for extension LineInfo lineInfo; try { //lineInfo = webServiceClient.OpenLine(clientHandle, extension); } catch (FaultException<PhoneSystemWebSDKErrorDetail>) { // TODO: log error return false; } // add extension to list of monitored extensions //monitoredExtensions.Add(extension, lineInfo.lineID); monitoredExtensions.Add(extension, 1); // start event poller thread if not already started if (eventWatcherThread.ThreadState == ThreadState.Stopped || eventWatcherThread.ThreadState == ThreadState.Unstarted) { eventWatcherThread.Start(); } return true; } } public bool UnsubscribeFromEventsForExtension(string extension) { if (!monitoredExtensions.Contains(extension)) { return false; } lock (monitoredExtensions.SyncRoot) { if (!monitoredExtensions.Contains(extension)) { return false; } // close line try { //webServiceClient.CloseLine(clientHandle, (int) monitoredExtensions[extension]); } catch (FaultException<PhoneSystemWebSDKErrorDetail>) { // TODO: log error return false; } // remove extension from list of monitored extensions monitoredExtensions.Remove(extension); // if we are not monitoring anything else, stop the poller and unregister the client if (monitoredExtensions.Count == 0) { eventWatcherThread.Abort(); UnregisterClient(); } return true; } } public bool IsExtensionMonitored(string extension) { lock (monitoredExtensions.SyncRoot) { return monitoredExtensions.Contains(extension); } } #endregion #region Dispose public void Dispose() { lock (l) { // close any open lines var extensions = monitoredExtensions.Keys.Cast<string>().ToList(); while (extensions.Count > 0) { UnsubscribeFromEventsForExtension(extensions[0]); extensions.RemoveAt(0); } if (!isClientRegistered) { return; } // unregister web service client UnregisterClient(); } } #endregion }

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• Rails running multiple delayed_job - lock tables

  - by pepernik

  Hey. I use delayed_job for background processing. I have 8 CPU server, MySQL and I start 7 delayed_job processes RAILS_ENV=production script/delayed_job -n 7 start Q1: I'm wondering is it possible that 2 or more delayed_job processes start processing the same process (the same record-row in the database delayed_jobs). I checked the code of the delayed_job plugin but can not find the lock directive in a way it should be. I think each process should lock the database table before executing an UPDATE on lock_by column. They lock the record simply by updating the locked_by field (UPDATE delayed_jobs SET locked_by...). Is that really enough? No locking needed? Why? I know that UPDATE has higher priority than SELECT but I think this does not have the effect in this case. My understanding of the multy-threaded situation is: Process1: Get waiting job X. [OK] Process2: Get waiting jobs X. [OK] Process1: Update locked_by field. [OK] Process2: Update locked_by field. [OK] Process1: Get waiting job X. [Already processed] Process2: Get waiting jobs X. [Already processed] I think in some cases more jobs can get the same information and can start processing the same process. Q2: Is 7 delayed_jobs a good number for 8CPU server? Why yes/not. Thx 10x!

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• Python threads all executing on a single core

  - by Rob Lourens

  I have a Python program that spawns many threads, runs 4 at a time, and each performs an expensive operation. Pseudocode: for object in list: t = Thread(target=process, args=(object)) # if fewer than 4 threads are currently running, t.start(). Otherwise, add t to queue But when the program is run, Activity Monitor in OS X shows that 1 of the 4 logical cores is at 100% and the others are at nearly 0. Obviously I can't force the OS to do anything but I've never had to pay attention to performance in multi-threaded code like this before so I was wondering if I'm just missing or misunderstanding something. Thanks.

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• What threading analysis tools do you recommend?

  - by glutz78

  My primary IDE is Visual Studio 2005 and I have a large C/C++ project. I'm interested in what thread analysis tools are recommended. By that I mean, I want a tool, static or dynamic, to help find race conditions, deadlocks, and the like. So far I've casually researched the following: 1. Intel Thread Checker: I don't believe that it ties into VS 2005? 2. Valgrind/Helgrind: free. 3. Coverity: this is a costly tool if i understand correctly. Anyone have experience with any of these or other? I'd much appreciate any advice. Thank you.

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• How to implement blocking request-reply using Java concurrency primitives?

  - by Uri

  My system consists of a "proxy" class that receives "request" packets, marshals them and sends them over the network to a server, which unmarshals them, processes, and returns some "response packet". My "submit" method on the proxy side should block until a reply is received to the request (packets have ids for identification and referencing purposes) or until a timeout is reached. If I was building this in early versions of Java, I would likely implement in my proxy a collection of "pending messages ids", where I would submit a message, and wait() on the corresponding id (with a timeout). When a reply was received, the handling thread would notify() on the corresponding id. Is there a better way to achieve this using an existing library class, perhaps in java.util.concurrency? If I went with the solution described above, what is the correct way to deal with the potential race condition where a reply arrives before wait() is invoked?

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• BeginInvoke on ObservableCollection not immediate.

  - by Padu Merloti

  In my code I subscribe to an event that happens on a different thread. Every time this event happens, I receive an string that is posted to the observable collection: Dispatcher currentDispatcher = Dispatcher.CurrentDispatcher; var SerialLog = new ObservableCollection<string>(); private void hitStation_RawCommandSent(object sender, StringEventArgs e) { string command = e.Value.Replace("\r\n", ""); Action dispatchAction = () => SerialLog.Add(command); currentDispatcher.BeginInvoke(dispatchAction, DispatcherPriority.Render); } The code below is in my view model (could be in the code behind, it doesn't matter in this case). When I call "hitstation.PrepareHit", the event above gets called a couple times, then I wait and call "hitStation.HitBall", and the event above gets called a couple more times. private void HitBall() { try { try { Mouse.OverrideCursor = Cursors.Wait; //prepare hit hitStation.PrepareHit(hitSpeed); Thread.Wait(1000); PlayWarning(); //hit hitStation.HitBall(hitSpeed); } catch (TimeoutException ex) { MessageBox.Show("Timeout hitting ball: " + ex.Message); } } finally { Mouse.OverrideCursor = null; } } The problem I'm having is that the ListBox that is bound to my SerialLog gets updated only when the HitBall method finishes. I was expecting seeing a bunch of updates from the PrepareHit, a pause and then a bunch more updates from the HitBall. I've tried a couple of DispatcherPriority arguments, but they don't seem to have any effect.

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• Sending multiple requests simultaneously to the Server using Selenium with Java

  - by gagneet

  I wish to send multiple requests to the server, simultaneously. The problem statement will be: Read a text file containing multiple URL’s. Open each URL in the web browser. Collect the Cookie information for each call, and store it to a file. Send another call: http://myserver.com:1111/cookie?out=text Store the output (body text) of this file to a separate file for each call made in 4 Open the next URL in the text file given in 1 and repeat steps 1-6. The above is to be run with multi-threading, so that I can send around 5-10 URL requests simultaneously. I have implemented something in Selenium using Java, but have not been able to do the multi-threading approach. Code is given below: package com.cookie.selenium; import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; import com.thoughtworks.selenium.*; public class ReadURL extends SeleneseTestCase { public void setUp() throws Exception { setUp("http://www.myserver.com/", "*chrome"); } public static void main(String args[]) { Selenium selenium = new DefaultSelenium("localhost", 4444, "*chrome", "http://myserver"); selenium.start(); selenium.setTimeout("30000000"); try { BufferedReader inputfile = new BufferedReader(new FileReader("C:\\url.txt")); BufferedReader cookietextfile = new BufferedReader(new FileReader("C:\\text.txt")); BufferedWriter cookiefile = new BufferedWriter(new FileWriter("C:\\cookie.txt")); BufferedWriter outputfile = null; String str; String cookiestr = "http://myserver.com:1111/cookie?out=text"; String filename = null; int i = 0; while ((str = inputfile.readLine()) != null) { selenium.createCookie("T=222redHyt345&f=5&r=fg&t=100",""); selenium.open( str ); selenium.waitForPageToLoad("120000"); String urlcookie = selenium.getCookie(); System.out.println( "URL :" + str ); System.out.println( "Cookie :" + urlcookie ); cookiefile.write( urlcookie ); cookiefile.newLine(); selenium.open( cookiestr ); selenium.waitForPageToLoad("120000"); String bodytext = selenium.getBodyText(); System.out.println("Body Text :" + bodytext); filename = "C:\\cookies\\" + i + ".txt"; outputfile = new BufferedWriter(new FileWriter( filename )); outputfile.write( bodytext ); outputfile.newLine(); i++; } inputfile.close(); outputfile.close(); cookiefile.close(); selenium.stop(); } catch (IOException e) { } } } What basically I am trying to do here is, open the first set of URL from a text file (which has list given of all the URL's i wish to open). Then when I capture the cookie information from here and store it, I open another window to output all the cookie information for that server to my browser window. This works fine when I do outside of Selenium code, but when I do it within the above code, it opens a "Save As..." popup and my tests stop. :-( I wish to save the contents of that second call to a new file, but have not been able to do the same. Also, if I have to send multiple such requests to the server, how would that be possible in Java using a Selenium Framework. Currently, I am opening multiple instances of the framework and running them with different parameters :-(

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• STA threads with SQLXMLBULKLOAD

  - by Christopher

  If I have N STA .NET Threads each performing an independent bulk load operation on a different database using the SQLXMLBulkLoad dll (which requires calling threads to be STA), is it possible for all bulk loads to be happening at the same time, or are they implicitly serialized due to the STA COM configuration? Thanks!

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• Is there a way to count threads using an instance?

  - by eriks

  I want to count number of threads that use some function - how can i do that? (maybe using ACE)

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• How the simples GUI countdown is supposed to work?

  - by Roman

  I am trying to write the simples GUI countdown. I found in Internet some code but it is already too fancy for me. I am trying to keep it as simple as possible. So, I just want to have a window saying "You have 10 second left". The number of second should decrease every second from 10 to 0. I wrote a code. And I think I am close to the working solution. But I still missing something. Could you pleas help me to find out what is wrong? Here is my code: import javax.swing.*; public class Countdown { static JLabel label; // Method which defines the appearance of the window. private static void showGUI() { JFrame frame = new JFrame("Simple Countdown"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JLabel label = new JLabel("Some Text"); frame.add(label); frame.pack(); frame.setVisible(true); } // Define a new thread in which the countdown is counting down. static Thread counter = new Thread() { public void run() { for (int i=10; i>0; i=i-1) { updateGUI(i,label); try {Thread.sleep(1000);} catch(InterruptedException e) {}; } } }; // A method which updates GUI (sets a new value of JLabel). private static void updateGUI(final int i, final JLabel label) { SwingUtilities.invokeLater(new Runnable(i,label) { public Runnable(int i, JLabel label) { this.i = i; this.label = label; } public void run() { label.setText("You have " + i + " seconds."); } }); } // The main method (entry point). public static void main(String[] args) { javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { showGUI(); //counter.start(); } }); //counter.start(); } } And I have several concrete question about this code: Where should I place the counter.start();? (In my code I put it on 2 places. Which one is correct?) Why compiler complains about the constructor for Runnable? It says that I have an invalid method declaration and I need to specify the returned type. ADDED: I made the suggested corrections. And then I execute the code and get: Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at Worker.run(Worker.java:12) In the Worker.java in the line 12 I have: label.setText("You have " + i + " seconds.");.

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• Java marshaller performance

  - by cbz

  Hi, I've used JAXB Marshaller as well as my own marshaller for marshalling pure java bean objects into XML. It has been observed that both of them require almost same time to marshal. The performance is not acceptable and needs to be improved. What are possible ways where we can improve performance of marshaller? Like threading?

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• Setting current culture with threads in ASP.NET MVC

  - by mare

  Here's an example of SetCulture attribute which inside does something like this: public void OnActionExecuting(ActionExecutingContext filterContext) { string cultureCode = SetCurrentLanguage(filterContext); if (string.IsNullOrEmpty(cultureCode)) return; HttpContext.Current.Response.Cookies.Add( new HttpCookie("Culture", cultureCode) { HttpOnly = true, Expires = DateTime.Now.AddYears(100) } ); filterContext.HttpContext.Session["Culture"] = cultureCode; CultureInfo culture = new CultureInfo(cultureCode); System.Threading.Thread.CurrentThread.CurrentCulture = culture; System.Threading.Thread.CurrentThread.CurrentUICulture = culture; } I was wondering how does this affect a site with multiple users logged on and each one setting their own culture? What is the scope of a thread here with regards to the IIS worker process (w3wp) that the site is running in?

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• Common Lisp implementation with CFFI and thread support on Mac, Windows, and Linux?

  - by mcandre

  Goal: Install Hunchentoot and be able to run Hunchentoot as a background thread. This is what I do: Install Common Lisp. Install Quicklisp. (ql:quickload "hunchentoot") (hunchentoot:start (make-instance 'hunchentoot:acceptor :port 4242)) The last command is supposed to start Hunchentoot, then return to the interpreter for further Common Lisp forms. For CLISP, SBCL, ABCL, ECL, and CCL, I get one of two results: Hunchentoot's dependency Bordeaux Threads fails to install. hunchentoot:start hangs. The web page never loads, and never 404s.

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• What is design principle behind Servlets being Singleton

  - by Sandeep Jindal

  A servlet container "generally" create one instance of a servlet and different threads of the same instance to serve multiple requests. (I know this can be changed using deprecated SingleThreadModel and other features, but this is the usual way). I thought, the simple reason behind this is performance gain, as creating threads is better than creating instances. But it seems this is not the reason. On the other hand, creating instances have little advantage that developers never have to worry about thread safety. I am trying to understand the reason for this decision over the trade-off of thread-safety.

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