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  • Am I correct in my assumption about synchronized block?

    - by kunjaan
    I have a method shout() with a synchronized block. private void shout(){ System.out.println("SHOUT " + Thread.currentThread().getName()); synchronized(this){ System.out.println("Synchronized Shout" + Thread.currentThread().getName()); try { Thread.sleep(50); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println("Synchronized Shout" + Thread.currentThread().getName()); } } If I have two Threads that run this method, am I correct in assuming that the two "Synchronized Shout" will always appear one after the other? There can be no other statements in between the "Synchronized Shout"?

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  • App only spawns one thread

    - by tipu
    I have what I thought was a thread-friendly app, and after doing some output I've concluded that of the 15 threads I am attempting to run, only one does. I have if __name__ == "__main__": fhf = FileHandlerFactory() tweet_manager = TweetManager("C:/Documents and Settings/Administrator/My Documents/My Dropbox/workspace/trie/Tweet Search Engine/data/partitioned_raw_tweets/raw_tweets.txt.001") start = time.time() for i in range(15): Indexer(tweet_manager, fhf).start() Then in my thread-entry point, I do def run(self): print(threading.current_thread()) self.index() That results in this: <Indexer(Thread-3, started 1168)> So of 15 threads that I thought were running, I'm only running one. Any idea as to why? Edit: code

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  • iPhone equivalent of Application.DoEvents();

    - by BahaiResearch.com
    iPHone: We use MonoTouch, but Obj-C answers are ok. My singleton domain object takes a while to get all the data so it runs internally parts of the fetch in a thread. I need to inform the UI that the domain is done. Currently I do this. Is there a better way? In WinForms I would call Application.DoEvents() instead of Thread Sleep. PlanDomain domain = PlanDomain.Instance (); while (domain.IsLoadingData) { Thread.Sleep (100); //this is the main UI thread } TableView.Hidden = false; TableView.Source = new TableSource (this); TableView.ReloadData ();

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  • WPF Dispatcher {"The calling thread cannot access this object because a different thread owns it."}

    - by user359446
    first I need to say that I´m noob with WPF and C#. Application: Create Mandelbrot Image (GUI) My disptacher works perfektly this this case: private void progressBarRefresh(){ while ((con.Progress) < 99) { progressBar1.Dispatcher.Invoke(DispatcherPriority.Send, new Action(delegate { progressBar1.Value = con.Progress; } )); } } I get the Message (Title) when tring to do this with the below code: bmp = BitmapSource.Create(width, height, 96, 96, pf, null, rawImage, stride); this.Dispatcher.Invoke(DispatcherPriority.Send, new Action(delegate { img.Source = bmp; ViewBox.Child = img; //vllt am schluss } )); I will try to explain how my program works. I created a new Thread (because GUI dont response) for the calculation of the pixels and the colors. In this Thread(Mehtod) I´m using the Dispatcher to Refresh my Image in the ViewBox after the calculations are ready. When I´m dont put the calculation in a seperate Thread then I can refresh or build my Image.

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  • Understanding Thread/BeginInvoke? [beginner]

    - by Moberg
    Consider the code: class Work { public void DoStuff(string s) { Console.WriteLine(s); // .. whatever } } class Master { private readonly Work work = new Work(); public void Execute() { string hello = "hello"; // (1) is this an ugly hack ? var thread1 = new Thread(new ParameterizedThreadStart(o => this.work.DoStuff((string)o))); thread1.Start(hello); thread1.Join(); // (2) is this similar to the one above? new Action<string>(s => this.work.DoStuff(s)).BeginInvoke(hello, null, null); } } Is (1) an acceptable way of easy starting some work in a seperate thread? If not a better alternative would be much appreciated. Is (2) doing the same? I guess what I ask is if a new thread is started, or.. Hope you can help a beginner to a better understanding :) /Moberg

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  • Ruby Thread with "watchdog"

    - by Sergio Campamá
    I'm implementing a ruby server for handling sockets being created from GPRS modules. The thing is that when the module powers down, there's no indication that the socket closed. I'm doing threads to handle multiple sockets with the same server. What I'm asking is this: Is there a way to use a timer inside a thread, reset it after every socket input, and that if it hits the timeout, closes the thread? Where can I find more information about this? EDIT: Code example that doesn't detect the socket closing require 'socket' server = TCPServer.open(41000) loop do Thread.start(server.accept) do |client| puts "Client connected" begin loop do line = client.readline open('log.txt', 'a') { |f| f.puts line.strip } end rescue puts "Client disconnected" end end end

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  • Events raised by BackgroundWorker not executed on expected thread

    - by Topdown
    A winforms dialog is using BackgroundWorker to perform some asynchronous operations with significant success. On occasion, the async process being run by the background worker will need to raise events to the winforms app for user response (a message that asks the user if they wish to cancel), the response of which captured in an CancelEventArgs type of the event. Being an implementation of threading, I would have expected the RaiseEvent of the worker to fire, and then the worker would continue, hence requiring me to pause the worker until the response is received. Instead however, the worker is held to wait for the code executed by the raise event to complete. It seems like method I am calling via the event call is actually on the worker thread used by the background worker, and I am surprised, since I expected to see it on the Main Thread which is where the mainform is running. Also surprisingly, there are no cross thread exceptions thrown. Can somebody please explain why this is not as I expect?

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  • Thread testing for time

    - by DanielFH
    Hi there :) I'm making a thread for my application that's going to do an exit operation at a given time (only hours and minutes, day/month doesn't matter). Is this the right way to do it, and also the right way to test for time? I'm testing for a 24 hour clock by the way, not AM / PM. I'm then in another class going to call this something like new Thread(new ExitThread()).start(); public class ExitThread implements Runnable { @Override public void run() { Date date = new Date(System.currentTimeMillis()); String time = new SimpleDateFormat("HHmmss").format(date); int currentTime = Integer.parseInt(time); int exitTime = 233000; while(true) { try { Thread.sleep(10000); } catch (InterruptedException e) { e.printStackTrace(); } if(currentTime >= exitTime ) { // do exit operation here } } } Thanks. //D

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  • ArrayBlockingQueue - How to "interrupt" a thread that is wating on .take() method

    - by bernhard
    I use an ArrayBlockingQueue in my code. Clients will wait untill an element becomes available: myBlockingQueue.take(); How can I "shutdown" my service in case no elements are present in the queue and the take() ist wating indefenitely for an element to become available? This method throws an InterruptedException. My question is, how can I "evoke" an Interrupted Exception so that take() will quit? (I also tought about notify(), but it seems I doesnt help here..) I know I could insert an special "EOF/QUIT" marker Element but is this really the only solution? UPDATE (regarding the comment, that points to another question with two solutions: one mentioned above using a "Poisoning Pill Object" and the second one is Thread.interrupt(): The myBlockingQueue.take() is used NOT in a Thread (extending Thread) but rather implements Runnable. It seems a Runnable does not provide the .interrupt() method? How could I interrupt the Runnable? Million Thanks Bernhard

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  • How to implement cancellable worker thread

    - by Arnold Zokas
    Hi, I'm trying to implement a cancellable worker thread using the new threading constructs in System.Threading.Tasks namespace. So far I have have come up with this implementation: public sealed class Scheduler { private CancellationTokenSource _cancellationTokenSource; public System.Threading.Tasks.Task Worker { get; private set; } public void Start() { _cancellationTokenSource = new CancellationTokenSource(); Worker = System.Threading.Tasks.Task.Factory.StartNew( () => RunTasks(_cancellationTokenSource.Token), _cancellationTokenSource.Token ); } private static void RunTasks(CancellationToken cancellationToken) { while (!cancellationToken.IsCancellationRequested) { Thread.Sleep(1000); // simulate work } } public void Stop() { try { _cancellationTokenSource.Cancel(); Worker.Wait(_cancellationTokenSource.Token); } catch (OperationCanceledException) { // OperationCanceledException is expected when a Task is cancelled. } } } When Stop() returns I expect Worker.Status to be TaskStatus.Canceled. My unit tests have shown that under certain conditions Worker.Status remains set to TaskStatus.Running. Is this a correct way to implement a cancellable worker thread?

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  • C# Thread issues

    - by Mike
    What I have going on is a listview being dynamically created from a previous button click. Then ti starts a background worker in which should clear out the listview and populate the iistview with new information every 30 seconds. I continously get: Cross-thread operation not valid: Control 'listView2' accessed from a thread other than the thread it was created on. private void watcherprocess1Updatelist() { listView2.Items.Clear(); string betaFilePath1 = @"C:\Alpha\watch1\watch1config.txt"; using (FileStream fs = new FileStream(betaFilePath1, FileMode.Open)) using (StreamReader rdr = new StreamReader((fs))) { while (!rdr.EndOfStream) { string[] betaFileLine = rdr.ReadLine().Split(','); using (WebClient webClient = new WebClient()) { string urlstatelevel = betaFileLine[0]; string html = webClient.DownloadString(urlstatelevel); File.AppendAllText(@"C:\Alpha\watch1\specificconfig.txt", html); } } }

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  • Windows Service And Thread Programming .NET

    - by Raghu
    I have developed windows service to process files whose records will be stored in database. When windows service finds a file it creates a thread and assigns each file to one thread. I have not used Thread Pool. I wanted to know when windows service is stopped, then how to identify how many threads are running and whether they are complete. If all the threads are executed then windows service can be stopped successfully. Otherwis windows service should wait until all threads are executed or aborted. How to implement this.

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  • Put Java Threading Class into a separate class

    - by erlord
    Consider following SWT code example: http://dev.eclipse.org/viewcvs/index.cgi/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet151.java?view=co How can I separate the inline defined class? Thread thread = new Thread() { public void run() { ... } }; I want to define a separate class which updates the table just like it does here. How do I pass the list back to the table? Example code?

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  • Efficient implementation of threads in the given scenario

    - by shadeMe
    I've got a winforms application that is set up in the following manner: 2 buttons, a textbox, a collection K, function X and another function, Y. Function X parses a large database and enumerates some of its data in the global collection. Button 1 calls function X. Function Y walks through the above collection and prints out the data in the textbox. Button 2 calls function Y. I'd like to call function X through a worker thread in such a way that: The form remains responsive to user input. This comes intrinsically from the use of a separate thread. There is never more than a single instance of function X running at any point in time. K can be accessed by both functions at all times. What would be the most efficient implementation of the above environment ?

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  • Final enum in Thread's run() method

    - by portoalet
    Hi, Why is the Elvis elvis definition has to be final to be used inside the Thread run() method? Elvis elvis = Elvis.INSTANCE; // ----> should be final Elvis elvis = Elvis.INSTANCE elvis.sing(4); Thread t1 = new Thread( new Runnable() { @Override public void run() { elvis.sing(6); // --------> elvis has to be final to compile } } ); public enum Elvis { INSTANCE(2); Elvis() { this.x = new AtomicInteger(0); } Elvis(int x){ this.x = new AtomicInteger(x); } private AtomicInteger x = new AtomicInteger(0); public int getX() { return x.get(); } public void setX(int x) {this.x = new AtomicInteger(x);} public void sing(int x) { this.x = new AtomicInteger(x); System.out.println("Elvis singing.." + x); } }

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  • Efficiently display file status when using background thread

    - by schmoopy
    How can i efficiently display the status of a file when using a background thread? For instance, lets say i have a 100MB file: when i do the code below via a thread (just as an example) it runs in about 1 min: foreach(byte b in file.bytes) { WriteByte(b, xxx); } But... if i want to update the user i have to use a delegate to update the UI from the main thread, the code below takes - FOREVER - literally i don't know how long im still waiting, ive created this post and its not even 30% done. int total = file.length; int current = 0; foreach(byte b in file.bytes) { current++; UpdateCurrentFileStatus(current, total); WriteByte(b, xxx); } public delegate void UpdateCurrentFileStatus(int cur, int total); public void UpdateCurrentFileStatus(int cur, int total) { // Check if invoke required, if so create instance of delegate // the update the UI if(this.InvokeRequired) { } else { UpdateUI(...) } }

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  • How to interrupt a waiting C++0x thread?

    - by doublep
    I'm considering to use C++0x threads in my application instead of Boost threads. However, I'm not sure how to reimplement what I have with standard C++0x threads since they don't seem to have an interrupt() method. My current setup is: a master thread that manages work; several worker threads that carry out master's commands. Workers call wait() on at least two different condition variables. Master has a "timed out" state: in this case it tells all workers to stop and give whatever result they got by then. With Boost threads master just uses interrupt_all() on a thread group, which causes workers to stop waiting. In case they are not waiting at the moment, master also sets a bool flag which workers check periodically. However, in C++0x std::thread I don't see any replacement for interrupt(). Do I miss something? If not, how can I implement the above scheme so that workers cannot just sleep forever?

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  • Async stream writing in a thread

    - by blez
    I have a thread in which I write to 2 streams. The problem is that the thread is blocked until the first one finishes writing (until all data is transferred on the other side of the pipe), and I don't want that. Is there a way to make it asynchronous? chunkOutput is a Dictionary filled with data from multiple threads, so the faster checking for existing keys is, the faster the pipe will write. void ConsumerMethod(object totalChunks) { while(true) { if (chunkOutput.ContainsKey(curChunk)) { if (outputStream != null && chunkOutput[curChunk].Length > 0) { outputStream.Write(chunkOutput[curChunk]); // <-- here it stops } ChunkDownloader.AppendData("outfile.dat", chunkOutput[curChunk], chunkOutput[curChunk].Length); curChunk++; if (curChunk >= (int) totalChunks) return; } Thread.Sleep(10); } }

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  • How to buffer stdout in memory and write it from a dedicated thread

    - by NickB
    I have a C application with many worker threads. It is essential that these do not block so where the worker threads need to write to a file on disk, I have them write to a circular buffer in memory, and then have a dedicated thread for writing that buffer to disk. The worker threads do not block any more. The dedicated thread can safely block while writing to disk without affecting the worker threads (it does not hold a lock while writing to disk). My memory buffer is tuned to be sufficiently large that the writer thread can keep up. This all works great. My question is, how do I implement something similar for stdout? I could macro printf() to write into a memory buffer, but I don't have control over all the code that might write to stdout (some of it is in third-party libraries). Thoughts? NickB

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  • iphone threading speed up startup of app

    - by BahaiResearch.com
    I have an app that must get data from the Sqlite database in order to display the first element to the User. I have created a domain object which wraps the DB access and is a thread safe singleton. Is this following strategy optimal to ensure the fastest load given the iPhone's file access and memory management capabilities in threaded apps: 1) In the AppDelegate's FinishedLaunching event the very first thing I do is create the domain singleton within a new thread. This will cause the domain object to go to Sqlite and get the data it needs without locking the UI thread. 2) I then call the standard Window methods to add the View and MakeKeyAndVisible etc. Is there an earlier stage in the AppDelegate where I should fire off the thread that creates the Domain Object and accesses Sqlite?

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  • Will this make the object thread-safe?

    - by sharptooth
    I have a native Visual C++ COM object and I need to make it completely thread-safe to be able to legally mark it as "free-threaded" in th system registry. Specifically I need to make sure that no more than one thread ever accesses any member variable of the object simultaneously. The catch is I'm almost sure that no sane consumer of my COM object will ever try to simultaneously use the object from more than one thread. So I want the solution as simple as possible as long as it meets the requirement above. Here's what I came up with. I add a mutex or critical section as a member variable of the object. Every COM-exposed method will acquire the mutex/section at the beginning and release before returning control. I understand that this solution doesn't provide fine-grained access and this might slow execution down, but since I suppose simultaneous access will not really occur I don't care of this. Will this solution suffice? Is there a simpler solution?

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  • event vs thread programming on server side.

    - by AlxPeter
    We are planning to start a fairly complex web-portal which is expected to attract good local traffic and I've been told by my boss to consider/analyse node.js for the serve side. I think scalability and multi-core support can be handled with an Nginx or Cherokee up in the front. 1) Is this node.js ready for some serious/big business? 2) Does this 'event/asynchronous' paradigm on server side has the potential to support the heavy traffic and data operation ? considering the fact that 'everything' is being processed in a single thread and all the live connections would be lost if it got crashed (though its easy to restart). 3) What are the advantages of event based programming compared to thread based style ? or vice-versa. (I know of higher cost associated with thread switching but hardware can be squeezed with event model.) Following are interesting but contradicting (to some extent) papers:- 1) http://www.usenix.org/events/hotos03/tech/full_papers/vonbehren/vonbehren_html 2) http://pdos.csail.mit.edu/~rtm/papers/dabek:event.pdf

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  • How to kill a thread immediately from another thread in java?

    - by Sara
    Hi, is there anyway to kill a thread or interrupt it immediately. Like in one of my thread, i call a method which takes time to execute (2-4 seconds). This method is in a while(boolean flag) block, so i can interrupt it from the main thread. But the problem is, if i interrupt it; it will wait till the executing loop is finished and then on next conditional check, it will stop execution. I want it to stop right then. Is there anyway to do this?

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  • prevent linux thread from being interrupted by scheduler

    - by johnnycrash
    How do you tell the thread scheduler in linux to not interrupt your thread for any reason? I am programming in user mode. Does simply locking a mutex acomplish this? I want to prevent other threads in my process from being scheduled when a certain function is executing. They would block and I would be wasting cpu cycles with context switches. I want any thread executing the function to be able to finish executing without interruption even if the threads' timeslice is exceeded.

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  • c++ simple start a function with its own thread

    - by user1397417
    i had once had a very simple one or two line code that would start a function with its own thread and continue running until application closed, c++ console app. lost the project it was in, and remember it was hard to find. cant find it online now. most example account for complicated multithreading situations. but i just need to open this one function in its own thread. hopefully someone knows what im talking about, or a similar solution. eg. start void abc in its own thread, no parameters

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