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  • Socket.Recieve Failing When Multithreaded

    - by Qua
    The following piece of code runs fine when parallelized to 4-5 threads, but starts to fail as the number of threads increase somewhere beyond 10 concurrentthreads int totalRecieved = 0; int recieved; StringBuilder contentSB = new StringBuilder(4000); while ((recieved = socket.Receive(buffer, SocketFlags.None)) > 0) { contentSB.Append(Encoding.ASCII.GetString(buffer, 0, recieved)); totalRecieved += recieved; } The Recieve method returns with zero bytes read, and if I continue calling the recieve method then I eventually get a 'An established connection was aborted by the software in your host machine'-exception. So I'm assuming that the host actually sent data and then closed the connection, but for some reason I never recieved it. I'm curious as to why this problem arises when there are a lot of threads. I'm thinking it must have something to do with the fact that each thread doesn't get as much execution time and therefore there are some idle time for the threads which causes this error. Just can't figure out why idle time would cause the socket not to recieve any data.

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  • c# multi threaded file processing

    - by user177883
    There is a folder that contains 1000 of small text files. I aim to parse and process all of them while more files are being populated in to the folder. My intention is to multithread this operation as the single threaded prototype took 6 minutes to process 1000 files. I like to have reader and writer thread(s) as following : while the reader thread(s) are reading the files, I d like to have writer thread(s) to process them. Once the reader is started reading a file, I d like to mark it as being processed, such as by renaming it, once it s read, rename it to completed. How to approach such multithreaded application ? Is it better to use a distributed hash table or a queue? Which data structure to use that would avoid locks? Would you have a better approach to this scheme that you like to share?

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  • Multi threading in WCF RIA Services

    - by synergetic
    I use WCF RIA Services to update customer database. In domain service: public void UpdateCustomer(Customer customer) { this.ObjectContext.Customers.AttachAsModified(customer); syncCustomer(customer); } After update, a database trigger launches and depending on the columns updated it may insert a new record in CustomerChange table. syncCustomer(customer) method is executed to check for a new record in the CustomerChange table and if found it will create a text file which contains customer information and forwards that file to external system for import. Now this synchronization may take a time so I wanted to execute it in different thread. So: private void syncCustomer(Customer customer) { this.ObjectContext.SaveChanges(); new Thread(() => syncCustomerInfo(customer.CustomerID)) { IsBackground = true }.Start(); } private void syncCustomerInfo(int customerID) { //Thread.Sleep(2000); //does real job here ... ... } The problem is in most cases syncCustomerInfo method cannot find any new CustomerChange record even if it was definitely there. If I force thread sleep then it finds a new record. I also looked Entity Framework events but the only event provided by object context is SavingChanges which occur before changes are saved. Please suggest me what else to try.

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  • Detecting a stale Mutex

    - by sum1stolemyname
    Is there any technique or tool available to detect this kind of a deadlock during runtime? picture this in a worker thread (one of several, normally 4-6) try WaitForSingleObject(myMutex); DoSTuffThatMightCauseAnException; Except ReleaseMutex(myMutex); end; or more generally is there a design-pattern to avoid these kind of bugs? I coded the above code in the little hous after a longer hacking run

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  • WCF threading - non-responsive UI

    - by Sphynx
    Hi everyone. I'm trying to configure some WCF stuff. Currently, I have a server which allows remote users to download files, and client. In the server, I use a ServiceHost class. I assume it should be running on a separate thread, however, the server UI (WinForms) becomes locked when someone downloads a file. Is there a way to manage the WCF threading model? Thank you!

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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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  • What is Erlang's concurrency model actually ?

    - by arun_suresh
    I was reading a paper recently Why Events are Bad. The paper is a comparative study of Event based and thread based highly concurrent servers and finally concludes stating that Threads are better than events in that scenario. I find that I am not able to classify what sort of concurrency model erlang exposes. Erlang provides Light Weight Processes, but those processes are suspended most of the time until it has received some event/message of some sort. /Arun

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  • Question about how to implement a c# host application with a plugin-like architecture

    - by devoured elysium
    I want to have an application that works as a Host to many other small applications. Each one of those applications should work as kind of plugin to this main application. I call them plugins not in the sense they add something to the main application, but because they can only work with this Host application as they depend on some of its services. My idea was to have each of those plugins run in a different app domain. The problem seems to be that my host application should have a set of services that my plugins will want to use and from what is my understanding making data flow in and out from different app domains is not that great of a thing. On one hand I'd like them to behave as stand-alone applications(although, as I said, they need to use lots of times the host application services), but on the other hand I'd like that if any of them crashes, my main application wouldn't suffer from it. What is the best (.NET) approach to this kind of situation? Make them all run on the same AppDomain but each one in a different Thread? Use different AppDomains? One for each "plugin"? How would I make them communicate with the Host Application? Any other way of doing this? Although speed is not an issue here, I wouldn't like for function calls to be that much slower than they are when we're working with just a regular .NET application. Thanks

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  • Java: Stopping a thread that has run for too long?

    - by Thomas King
    Say I've got something like this public void run(){ Thread behaviourThread = new Thread(abstractBehaviours[i]); behaviourThread.start(); } And I want to wait until abstractBehaviours[i] run method has either finished or run for 5000 milliseconds. How do I do that? behaviourThread.join(5000) doesn't seem to do that afaik (something is wrong with my code and I've put it down to that). All the abstract abstractBehaviour class is of course Runnable. I don't want to implement it inside each run method as that seems ugly and there are many different behaviours, I'd much rather have it in the calling/executing thread and do it just once. Solutions? First time doing something as threaded as this. Thanks!

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  • C# : What if a static method is called from multiple threads?

    - by Holli
    In my Application I have a static method that is called from multiple threads at the same time. Is there any danger of my data being mixed up? In my first attempt the method was not static and I was creating multiple instance of the class. In that case my data got mixed up somehow. I am not sure how this happens because it only happens sometimes. I am still debugging. But now the method is static on I have no problems so far. Maybe it's just luck. I don't know for sure.

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  • Code runs 6 times slower with 2 threads than with 1

    - by Edward Bird
    So I have written some code to experiment with threads and do some testing. The code should create some numbers and then find the mean of those numbers. I think it is just easier to show you what I have so far. I was expecting with two threads that the code would run about 2 times as fast. Measuring it with a stopwatch I think it runs about 6 times slower! void findmean(std::vector<double>*, std::size_t, std::size_t, double*); int main(int argn, char** argv) { // Program entry point std::cout << "Generating data..." << std::endl; // Create a vector containing many variables std::vector<double> data; for(uint32_t i = 1; i <= 1024 * 1024 * 128; i ++) data.push_back(i); // Calculate mean using 1 core double mean = 0; std::cout << "Calculating mean, 1 Thread..." << std::endl; findmean(&data, 0, data.size(), &mean); mean /= (double)data.size(); // Print result std::cout << " Mean=" << mean << std::endl; // Repeat, using two threads std::vector<std::thread> thread; std::vector<double> result; result.push_back(0.0); result.push_back(0.0); std::cout << "Calculating mean, 2 Threads..." << std::endl; // Run threads uint32_t halfsize = data.size() / 2; uint32_t A = 0; uint32_t B, C, D; // Split the data into two blocks if(data.size() % 2 == 0) { B = C = D = halfsize; } else if(data.size() % 2 == 1) { B = C = halfsize; D = hsz + 1; } // Run with two threads thread.push_back(std::thread(findmean, &data, A, B, &(result[0]))); thread.push_back(std::thread(findmean, &data, C, D , &(result[1]))); // Join threads thread[0].join(); thread[1].join(); // Calculate result mean = result[0] + result[1]; mean /= (double)data.size(); // Print result std::cout << " Mean=" << mean << std::endl; // Return return EXIT_SUCCESS; } void findmean(std::vector<double>* datavec, std::size_t start, std::size_t length, double* result) { for(uint32_t i = 0; i < length; i ++) { *result += (*datavec).at(start + i); } } I don't think this code is exactly wonderful, if you could suggest ways of improving it then I would be grateful for that also.

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  • How can I make a single WCF method ConcurrencyMode.Multiple when service is ConcurencyMode.Single

    - by Michael Hedgpeth
    I have a service which is defined as ConcurrencyMode.Single: [ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Single, UseSynchronizationContext = false, InstanceContextMode = InstanceContextMode.PerSession, IncludeExceptionDetailInFaults = true)] public class MyService : IMyService This service provides a method to tell the client what it's currently working on: [OperationContract] string GetCurrentTaskDescription(); Is there a way to make this particular method allowable while another long-running task is running where all other methods still follow the single-threaded concurrency model?

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  • For single-producer, single-consumer should I use a BlockingCollection or a ConcurrentQueue?

    - by Jonathan Allen
    For single-producer, single-consumer should I use a BlockingCollection or a ConcurrentQueue? Concerns: * My goal is to pull up to 100 items at a time and send them as a batch to the next step. * If I use a ConcurrentQueue, I have to manually cause it to go asleep when there is no work to be done. Otherwise I waste CPU cycles on spinning. * If I use a BlockingQueue and I only have 99 work items, it could indefinitely block until there the 100th item arrives. http://msdn.microsoft.com/en-us/library/system.collections.concurrent.aspx

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  • Does WCF use the ThreadPool to bring up new instances for a PerCall service?

    - by theburningmonk
    Hi, for a PerCall WCF service whose throttling has been set to be high (say, 200 max concurrent calls) would WCF bring up a new instance and invoke the request on a threadpool thread? If it does, then does this have an impact on the total number of concurrent calls allowed? I ask because I don't seem to ever hit the max number of concurrent calls I've set in the service throttling config but instead a fraction of that number - up to 50 on a 100 MaxConcurrentCalls setting and 160 on a 200 MaxConcurrentCalls setting. Thanks,

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  • Async call Objective C iphone

    - by Sam
    Hi guys, I'm trying to get data from a website- xml. Everything works fine. But the UIButton remains pressed until the xml data is returned and thus if theres a problem with the internet service, it cant be corrected and the app is virtually unusable. here are the calls: { AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate]; if(!appDelegate.XMLdataArray.count > 0){ [UIApplication sharedApplication].networkActivityIndicatorVisible = YES; [appDelegate GetApps]; //function that retrieves data from Website and puts into the array - XMLdataArray. } XMLViewController *controller = [[XMLViewController alloc] initWithNibName:@"MedGearsApps" bundle:nil]; [self.navigationController pushViewController:controller animated:YES]; [controller release]; } It works fine, but how can I make the view buttons functional with getting stuck. In other words, I just want the UIButton and other UIButtons to be functional whiles the thing works in the background. I heard about performSelectorInMainThread but i cant put it to practice correctly any help is appreciated :)

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  • Thread runs only once

    - by folone
    When a Thread is finished, you cannot run it once more, using start() method: it throws an Exception. Could anyone explain, why? What stands behind such an architectural decision?

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  • C++ threaded class design from non-threaded class

    - by macs
    I'm working on a library doing audio encoding/decoding. The encoder shall be able to use multiple cores (i.e. multiple threads, using boost library), if available. What i have right now is a class that performs all encoding-relevant operations. The next step i want to take is to make that class threaded. So i'm wondering how to do this. I thought about writing a thread-class, creating n threads for n cores and then calling the encoder with the appropriate arguments. But maybe this is an overkill and there is no need for another class, so i'm going to make use of the "user interface" for thread-creation. I hope there are any suggestions.

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  • How to detect that the internet connection has got disconnected through a java desktop application?

    - by Yatendra Goel
    I am developing a Java Desktop Application that access internet. It is a multi-threaded application, each thread do the same work (means each thread is an instance of same Thread class). Now, as all the threads need internet connection to be active, there should be some mechanism that detects whether an internet connection is active or not. Q1. How to detect whether the internet connection is active or not? Q2. Where to implement this internet-status-check-mechanism code? Should I start a separate thread for checking internet status regularly and notifies all the threads when the status changes from one state to another? Or should I let each thread check for the internet-status itself? Q3. This issue should be a very common issue as every application accessing an internet should deal with this problem. So how other developers usually deal with this problem? Q4. If you could give me a reference to a good demo application that addresses this issue then it would greatly help me.

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  • Printdialog in multithreaded wpf window thrown TargetInvocationException

    - by Nils
    I have designed a multithreaded app, which is starting most windows in an dedicated thread like this: Thread newWindowThread = new Thread(new ThreadStart(ThreadStartingPoint)); newWindowThread.SetApartmentState(ApartmentState.STA); newWindowThread.IsBackground = true; newWindowThread.Start(); However, if in one of those window-in-own-thread I try to print something by simply calling PrintDialog pDialog = new PrintDialog(); bool? doPrint = pDialog.ShowDialog(); I get a TargetInvocationException - it does look like the PrintDialog does not reside in the same thread as my window. Is there any way to create a thread-agnostic (or "thread-save") PrinterDialog ?

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  • Multi-threaded library calls in ASP.NET page request.

    - by ProfK
    I have an ASP.NET app, very basic, but right now too much code to post if we're lucky and I don't have to. We have a class called ReportGenerator. On a button click, method GenerateReports is called. It makes an async call to InternalGenerateReports using ThreadPool.QueueUserWorkItem and returns, ending the ASP.NET response. It doesn't provide any completion callback or anything. InternalGenerateReports creates and maintains five threads in the threadpool, one report per thread, also using QueueUserWorkItem, by 'creating' five threads, also with and waiting until calls on all of them complete, in a loop. Each thread uses an ASP.NET ReportViewer control to render a report to HTML. That is, for 200 reports, InternalGenerateReports should create 5 threads 40 times. As threads complete, report data is queued, and when all five have completed, report data is flushed to disk. My biggest problems are that after running for just one report, the aspnet process is 'hung', and also that at around 200 reports, the app just hangs. I just simplified this code to run in a single thread, and this works fine. Before we get into details like my code, is there anything obvious in the above scendario that might be wrong?

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  • My Thread Programs Crash

    - by zp26
    I have a problem with threads objectiveC. The line of code below contains the recv block the program waiting for a datum. My intention is to launch a thread parallel to the program so that this statement does not block any application. I put this code in my program but when active switch the program crashes. Enter the code. -(IBAction)Chat{ if(switchChat.on){ buttonInvio.enabled = TRUE; fieldInvio.enabled = TRUE; [NSThread detachNewThreadSelector:@selector(riceviDatiServer) toTarget:self withObject:nil]; } else { buttonInvio.enabled = FALSE; fieldInvio.enabled = FALSE; } -(void)riceviDatiServer{ NSAutoreleasePool *pool = [[NSAutoreleasePool alloc]init]; int ricevuti; NSString *datiRicevuti; ricevuti = recv(temp, &datiRicevuti, datiRicevuti.length, 0); labelRicezione.text = [[NSString alloc] initWithFormat:@"%s.... %d", datiRicevuti, ricevuti]; [pool release]; }

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  • Asynchronous Delegates Vs Thread/ThreadPool?

    - by claws
    Hello, I need to execute 3 parallel tasks and after completion of each task they should call the same function which prints out the results. I don't understand in .net why we have Asychronous calling (delegate.BeginInvoke() & delegate.EndInvoke()) as well as Thread class? I'm little confused which one to use when? Now in this particular case, what should I use Asychronous calling or Thread class? I'm using C#.

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  • Diffrernce between BackgroundWorker.ReportProgress() and Control.Invoke()

    - by ohadsc
    What is the difference between options 1 and 2 in the following? private void BGW_DoWork(object sender, DoWorkEventArgs e) { for (int i=1; i<=100; i++) { string txt = i.ToString(); if (Test_Check.Checked) //OPTION 1 Test_BackgroundWorker.ReportProgress(i, txt); else //OPTION 2 this.Invoke((Action<int, string>)UpdateGUI, new object[] {i, txt}); } } private void BGW_ProgressChanged(object sender, ProgressChangedEventArgs e) { UpdateGUI(e.ProgressPercentage, (string)e.UserState); } private void UpdateGUI(int percent, string txt) { Test_ProgressBar.Value = percent; Test_RichTextBox.AppendText(txt + Environment.NewLine); } Looking at reflector, the Control.Invoke() appears to use: this.FindMarshalingControl().MarshaledInvoke(this, method, args, 1); whereas BackgroundWorker.Invoke() appears to use: this.asyncOperation.Post(this.progressReporter, args); (I'm just guessing these are the relevant function calls.) If I understand correctly, BGW Posts to the WinForms window its progress report request, whereas Control.Invoke uses a CLR mechanism to invoke on the right thread. Am I close? And if so, what are the repercussions of using either ? Thanks

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