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  • Using two threads and controlling one from the other in java?

    - by sidra
    Can someone please help me out. I need to use two threads in a way that one thread will run permanently while(true) and will keep track of a positioning pointer (some random value coming in form a method). This thread has a logic, if the value equals something, it should start the new thread. And if the value does not equal it should stop the other thread. Can someone give me some code snippet (block level) about how to realize this?

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  • Perform tasks with delay, without delaying web response (ASP.NET)

    - by Tomas Lycken
    I'm working on a feature that needs to send two text messages with a 30 second delay, and it is crucial that both text messages are sent. Currently, this feature is built with ajax requests, that are sent with a 30 second javascript delay, but since this requires the user to have his browser open and left on the same page for at least 30 seconds, it is not a method I like. Instead, I have tried to solve this with threading. This is what I've done: Public Shared Sub Larma() Dim thread As New System.Threading.Thread(AddressOf Larma_Thread) thread.Start() End Sub Private Shared Sub Larma_Thread() StartaLarm() Thread.Sleep(1000 * 30) StoppaLarm() End Sub A web handler calls Larma(), and StartaLarm() and StoppaLarm() are the methods that send the first and second text messages respectively. However, I only get the first text message delivered - the second is never sent. Am I doing something wrong here? I have no deep understanding of how threading works in ASP.NET, so please let me know how to accomplish this.

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  • unprotected access to member in property get

    - by Lenik
    I have a property public ObservableCollection<string> Name { get { return _nameCache; } } _nameCache is updated by multiple threads in other class methods. The updates are guarded by a lock. The question is: should I use the same lock around my return statement? Will not using a lock lead to a race condition?

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  • How to have a run in an Service?

    - by user1497664
    I have implemented an service that runs in a seperate process. This service contains a separate thread where i have a socket connection. This thread has a run() where it is continuously sending data to the port. My problem is after triggering the run() in the thread i don't get any contact with it anymore, i can see in the program that have open the socket that it consciously sends the data but the idea was that i while it is running i could change data that it sends for an example time. here is my run in the external thread: public void run() { if(run) { // Team and player names message is sent when entering in a game setBaseMessage(); SendMessageToCOMPort(base_message + CalculateCRC(base_message)); sleep(); // waits for 100 ms } } Anyone have any idea what might be wrong ?

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  • Any reason NOT to slap the 'synchronized' keyword everywhere?

    - by unknown
    In my java project, almost every non-static method I've written is synchronized. I've decided to fix up some code today, by removing most of the synchronized keywords. Right there I created several threading issues that took quite a while to fix, with no increase in performance. In the end I reverted everything. I don't see anyone else writing code with "synchronized" everywhere. So is there any reason I shouldn't have "synchronized" everywhere? What if I don't care too much about performance (ie. the method isn't called more than once every few seconds)?

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  • How to show and update popup in 1 thread

    - by user3713986
    I have 1 app. 2 Forms are MainFrm and PopupFrm, 1 thread to update some information to PopupFrm Now to update PopupFrm i use: In MainFrm.cs private PopupFrm mypop; MainFrm() { .... PopupFrm mypop= new PopupFrm(); mypop.Show(); } MyThread() { Process GetData();... mypop.Update(); ... } In PopupFrm.cs public void Update() { this.Invoke((MethodInvoker)delegate .... }); } Problem here that mypopup alway display when MainFrm display (Start application not when has data to update). So i change MainFrm.cs to : private PopupFrm mypop; private bool firstdisplay=false; MainFrm() { .... PopupFrm mypop= new PopupFrm(); //mypop.Show(); } MyThread() { Process GetData();... if(!firstdisplay) { mypop.Show(); firstdisplay=true; } mypop.Update(); ... } But it can not update Popup GUI. So how can i fix this issue ? Thanks all.

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  • Threading in java vs C#

    - by ffayyaz
    I need a little confirmation over something i am confused at . I know how threads work in java. new DialList(string a , string b).start(); // where DialList is a class public class DialList extends Thread { public DialList(String a, string b) { FilePath = a; ThreadLogFile = b"; } public void run() { // some code to run in different thread } } Now i want to run same code in C# , Shall i put the code which is in run() into a method and do something like Thread t = new Thread (runcsharp); // Kick off a new thread t.Start(); static void runcsharp() { // code } or is there some other way to do it ?

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  • What does the GDI+ background thread do?

    - by uj
    Upon initialization, GDI+ (non .NET) creates a background thread, which can optionally be suppressed subject to calling some hook functions. MSDN, however, doesn't say what this thread actually does. Google doesn't seem to know either. What is it for?

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  • Dispatcher.CheckAccess() isn't working from my console application, is there a better way.

    - by zimmer62
    I wrote an application in WPF / VB and separated the business logic and UI into different projects. The business layer uses a serial port which runs on a different thread, Now that I'm trying to write a command line interface for the same business layer, it seems to fail when .Invoke() is called. (no error, just doesn't work) I'm pretty sure the reason I had to add in checkaccess and .invoke was because I have collections that would be changed during processing the serial port data and wanted the NotifyCollectionChanged to be handled by WPF data binding. (The reason I'm not 100% sure is because it was months ago I wrote that part and it all worked great from the GUI, now adding the console app has made me rethink some of this) I would like my business layer to run these processes on the thread they were created, I need this to work from both my GUI version and the command line version. Am I misusing the Dispatcher in my business layer? Is there a better way to handle an event from the serial port, and then return to the main thread to processes the data?

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  • Running a loop (such as one for a mock webserver) within a thread

    - by bob c
    I'm trying to run a mock webserver within a thread within a class. I've tried passing the class' @server property to the thread block but as soon as I try to do server.accept the thread stops. Is there some way to make this work? I want to basically be able to run a webserver off of this script while still taking user input via stdin.gets. Is this possible? class Server def initialize() @server = TCPServer.new(8080) end def run() @thread = Thread.new(@server) { |server| while true newsock = server.accept puts "some stuff after accept!" next if !newsock # some other stuff end } end end def processCommand() # some user commands here end test = Server.new while true do processCommand(STDIN.gets) end In the above sample, the thread dies on server.accept

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  • Java Multi threading - Avoid duplicate request processing

    - by seawaves
    I have following multi threaded environment scenario - Requests are coming to a method and I want to avoid the duplicate processing of concurrent requests coming. As multiple similar requests might be waiting for being processed in blocked state. I used hashtable to keep track of processed request, but it will create memory leaks, so how should keep track of processed request and avoid the same requests to be processed which may be in blocking state.

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  • how a thread can signal when it's finished?

    - by Kyle
    #include <iostream> #include <boost/thread.hpp> using std::endl; using std::cout; using namespace boost; mutex running_mutex; struct dostuff { volatile bool running; dostuff() : running(true) {} void operator()(int x) { cout << "dostuff beginning " << x << endl; this_thread::sleep(posix_time::seconds(2)); cout << "dostuff is done doing stuff" << endl; mutex::scoped_lock running_lock(running_mutex); running = false; } }; bool is_running(dostuff& doer) { mutex::scoped_lock running_lock(running_mutex); return doer.running; } int main() { cout << "Begin.." << endl; dostuff doer; thread t(doer, 4); if (is_running(doer)) cout << "Cool, it's running.\n"; this_thread::sleep(posix_time::seconds(3)); if (!is_running(doer)) cout << "Cool, it's done now.\n"; else cout << "still running? why\n"; // This happens! :( return 0; } Why is the output of the above program: Begin.. Cool, it's running. dostuff beginning 4 dostuff is done doing stuff still running? why How can dostuff correctly flag when it is done? I do not want to sit around waiting for it, I just want to be notified when it's done.

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  • C# WPF Unable to control Textboxes

    - by Bo0m3r
    I'm a beginner in coding into C#. While I'm launching a process I can't controls my textboxes. I found some answers on this forum but the explaination is a bit to difficult for me to implement it for my problem. I created a small program that will run a batch file to make a backup. While the backup is running I can't modify my textboxes, disabling buttons etc... I already saw that this is normal but I don't know how to implement the solutions. My last attempt was with Dispatcher.invoke as you can see below. public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); tb_Status.Text = "Ready"; } public void status() { Dispatcher.Invoke(DispatcherPriority.Send, new Action( () => { tb_Status.Text = "The backup is running!"; } ) ); } public void process() { try { Process p = new Process(); p.StartInfo.WindowStyle = ProcessWindowStyle.Minimized; p.StartInfo.CreateNoWindow = true; p.StartInfo.UseShellExecute = false; p.StartInfo.RedirectStandardOutput = true; p.StartInfo.FileName = "Robocopy.bat"; p.Start(); string output = p.StandardOutput.ReadToEnd(); p.WaitForExit(); tb_Output.Text = File.ReadAllText("Backup\\log.txt"); } catch (Exception ex) { tb_Status.Text = ex.Message.ToString(); } } private void Bt_Start_Click(object sender, EventArgs e) { status(); Directory.CreateDirectory("Backup"); process(); tb_Status.Text = "The backup finished"; File.Delete("Backup\\log.txt"); } } } Any help is appreciated!

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  • Is a Critical Section around an integer getter and setter redundant?

    - by Tim Gradwell
    Do critical sections inside trivial int accessors actually do anything useful? int GetFoo() { CriticalSection(crit_id); return foo; } void SetFoo(int value) { CriticalSection(crit_id); foo = value; } Is it possible for two threads to be attempting to read and write foo simultaneously? I'd have thought 'no' unless integers are written byte-at-a-time, in which case I can see the use. But I'd have though modern cpus would read/write integers in a single atomic action...

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  • C# start a static thread

    - by user595605
    I have a Queue of items I want to process in a thread, and any instance of a class can add items to the Queue to be processed. My idea for doing this is to have a static Thread in the class that processes the items, the only problem is that I don't know where to start this thread, since I can't start it in its initialization. Is there a way I can start a static thread? Or should I be changing the architecture completely?

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  • OpenGL multiple threads, variable handling [closed]

    - by toeplitz
    I have written an OpenGL program which runs in the following way: Main: - Initialize SDL - Create thread which has the OpenGL context: - Renderloop - Set camera (view) matrix with glUniform. - glDrawElements() .... etc. - Swapbuffers(); - Main SDL loop handling input events and such. - Update camera matrix of type glm::mat4. This is how I pass my camera object to the class that handles opengl. Camera *cam = new Camera(); gl.setCam(cam); where void setCam(Camera *camera) { this->camera = camera; } For rendering in the opengl context thread, this happens: glm::mat4 modelView = camera->view * model; glUniformMatrix4fv(shader->bindUniform("modelView"), 1, GL_FALSE, glm::value_ptr(modelView)); In the main program where my SDL and other things are handles I then recompute the view matrix. This his working fine without me using any mutex locks. Is this correct? On the other hand, I add objects to my scene by an "upload queue" and in this case I have to mutex lock my upload queue vector (vector class type) when adding items to it or else the program crashes. In summary: I recompute my matrix in a different thread and then use it in the opengl thread without any mutex lock. Why is this working? Edit: I think my question is similar to what was asked here: Should I lock a variable in one thread if I only need it's value in other threads, and why does it work if I don't?, only in my case it is even more simple with only one matrix being changed.

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  • How to call 3 threads sequentially many times?

    - by Hello
    How to call 3 threads sequentially many times? For example: In iteration 1, execution order should be "Thread0-thread1-thread2" then in iteration 2 should be same i.e "Thread0 - thread1-thread2" and so on. The sample code is just executing 3 threads only once. It is not going to 2nd iteration. Thread0 = CreateThread( NULL,0,ThreadProc0, NULL, CREATE_SUSPENDED, &ThreadID); Thread1 = CreateThread( NULL,0,ThreadProc1, NULL, CREATE_SUSPENDED, &ThreadID); Thread2 = CreateThread( NULL,0,ThreadProc2, NULL, CREATE_SUSPENDED, &ThreadID); for(i=0;i<iterations;i++) //Iterations in calling threads { ResumeThread(Thread0); WaitForSingleObject(Thread0, INFINITE); ResumeThread(Thread1); WaitForSingleObject(Thread1, INFINITE); ResumeThread(Thread2); WaitForSingleObject(Thread2, INFINITE); } // Close thread and semaphore handles

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  • how to print correctly the handling thread on Windows?

    - by make
    Hi, Could someone please tell us on how to print correctly the handling thread in windows? Actually I tried several ways but it doesn't return the right number as in Unix-variant, as such e.g.: cout << " with thread " << pthread_self << endl; cout << " with thread " << pthread_self().p << endl; Thanks for your replies:

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  • Execute PHP file in background

    - by Spyric
    I have some php code, that execute for a very long time. I need to realise next scheme: User enter on some page(page 1) This page starts execution of my large PHP script in background .(Every change is writting to database) We sent every N seconds query to database to get current status of execution. I don't want to use exec command because 1000 users makes 1000 php processes. It's not way for me...

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  • Why are my thread being terminated ?

    - by Sephy
    Hi, I'm trying to repeat calls to methods through 3 differents threads. But after I start my threads, during the next iteration of my loop, they are all terminated so nothing is executed... The code is as follows : public static void main(String[] args) { main = new Main(); pollingThread.start(); } static Thread pollingThread = new Thread() { @Override public void run() { while (isRunning) { main.poll(); // test the state of the threads try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } }; }; public void poll() { if (clientThread == null) { clientThread = new Thread(new Runnable() { @Override public void run() { //create some objects } }); clientThread.start(); } else if (clientThread.isAlive()) { // do some treatment } if (gestionnaireThread == null) { gestionnaireThread = new Thread(new Runnable() { @Override public void run() { //create some objects }; }); gestionnaireThread.start(); } else if (gestionnaireThread.isAlive()) { // do some treatment } if (marchandThread == null) { marchandThread = new Thread(new Runnable() { @Override public void run() { // create some objects }; }); marchandThread.start(); } else if (marchandThread.isAlive()) { // do some treatment } } And for some reason, when I test the state of my different threads, they appear as runnable and then a the 2nd iteration, they are all terminated... What am I doing wrong? I actually have no error, but the threads are terminated and so my loop keeps looping and telling me the threads are terminated.... Thanks for any help.

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