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  • Java concurrency - Should block or yield?

    - by teto
    Hi, I have multiple threads each one with its own private concurrent queue and all they do is run an infinite loop retrieving messages from it. It could happen that one of the queues doesn't receive messages for a period of time (maybe a couple seconds), and also they could come in big bursts and fast processing is necessary. I would like to know what would be the most appropriate to do in the first case: use a blocking queue and block the thread until I have more input or do a Thread.yield()? I want to have as much CPU resources available as possible at a given time, as the number of concurrent threads may increase with time, but also I don't want the message processing to fall behind, as there is no guarantee of when the thread will be reescheduled for execution when doing a yield(). I know that hardware, operating system and other factors play an important role here, but setting that aside and looking at it from a Java (JVM?) point of view, what would be the most optimal?

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  • How to use CriticalSection - MFC?

    - by mapples
    I' am working on a small example and am a bit of curious using criticalsection in my example. What I'am doing is,I have a CStringArray(which has 10 elements added to it).I want to copy these 10 elements(string) to another CStringArray(am doing this to understand threading and Critical section),I have created 2 threads,Thread1 will copy the first 5 element to another CStringArray and Thread2 will copy the rest.Here two CStringArray are being used,I know only 1 thread can access it at a time.I wanted to know how this can be solved by using criticalsection or any other method. void CThreadingEx4Dlg::OnBnClickedOk() { // TODO: Add your control notification handler code here thread1 = AfxBeginThread((AFX_THREADPROC)MyThreadFunction1,this); thread2 = AfxBeginThread((AFX_THREADPROC)MyThreadFunction2,this); } UINT MyThreadFunction1(LPARAM lparam) { CThreadingEx4Dlg* pthis = (CThreadingEx4Dlg*)lparam; pthis->MyFunction(0,5); return 0; } UINT MyThreadFunction2(LPARAM lparam) { CThreadingEx4Dlg* pthis = (CThreadingEx4Dlg*)lparam; pthis->MyFunction(6,10); return 0; } void CThreadingEx4Dlg::MyFunction(int minCount,int maxCount) { for(int i=minCount;i<=maxCount;i++) { CString temp; temp = myArray.GetAt(i); myShiftArray.Add(temp); } }

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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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  • c# run process without freezing my App's GUI

    - by Data-Base
    Hello, I want to start a process (calling another program), currently the external program takes time (it is normal)! but it freezes my GUI I saw allot of examples and I'm learning, it is hard to figure it out, trying to read and learn threading, but it is not that easy (at least for me) and good simple tutorial or code sample? cheers

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  • Thread-safe get (accessor method)

    - by sonofdelphi
    I'm currently using the following code for thread-safe access of a variable. int gnVariable; void getVariableValue(int *pnValue) { acquireLock(); //Acquires the protection mechanism *pnValue = gnVariable; releaseLock(); //Releasing the protection mechanism } I would like to change my API signature to a more user-friendly int getVariableValue(void); How should I rewrite the function - such that the users of the API don't have to bother about the locking/unlocking details?

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  • Please suggest good book/website to for Threads and Concurrency?

    - by learner
    I have gone through Head First Java and some other sites but I couldn't find complete stuff related to Threads and additional concurrency packages at one place. Please suggest a book/website which covers complete Threads with more details like Synchronize and locking of objects More detailed about volatile Visibility issues in Threads java.util.concurrent package java.util.concurrent.atomic package

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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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  • How do I make child thread exit when main thread exit?

    - by httpinterpret
    void forloop2() { int i = 0; while(TRUE) { printf("forloop2\n"); } } int main() { GThread *Thread1; GtkWidget *window; g_thread_init(NULL); gdk_threads_init(); gdk_threads_enter (); Thread1 = g_thread_create((GThreadFunc)forloop2, NULL, TRUE, NULL); gtk_init(NULL, NULL); window = gtk_window_new(GTK_WINDOW_TOPLEVEL); gtk_widget_show_all (window); gtk_main(); g_thread_join(Thread1); gdk_threads_leave (); } When I close the window, how to make Thread1 also exit?

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  • ThreadQueue problems in "Accelerated C# 2008"

    - by Singlet
    Example for threading queue book "Accelerated C# 2008" (CrudeThreadPool class) not work correctly. If I insert long job in WorkFunction() on 2-processor machine executing for next task don't run before first is over. How to solve this problem? I want to load the processor to 100 percent public class CrudeThreadPool { static readonly int MAX_WORK_THREADS = 4; static readonly int WAIT_TIMEOUT = 2000; public delegate void WorkDelegate(); public CrudeThreadPool() { stop = 0; workLock = new Object(); workQueue = new Queue(); threads = new Thread[ MAX_WORK_THREADS ]; for( int i = 0; i < MAX_WORK_THREADS; ++i ) { threads[i] = new Thread( new ThreadStart(this.ThreadFunc) ); threads[i].Start(); } } private void ThreadFunc() { lock( workLock ) { int shouldStop = 0; do { shouldStop = Interlocked.Exchange( ref stop, stop ); if( shouldStop == 0 ) { WorkDelegate workItem = null; if( Monitor.Wait(workLock, WAIT_TIMEOUT) ) { // Process the item on the front of the queue lock( workQueue ) { workItem =(WorkDelegate) workQueue.Dequeue(); } workItem(); } } } while( shouldStop == 0 ); } } public void SubmitWorkItem( WorkDelegate item ) { lock( workLock ) { lock( workQueue ) { workQueue.Enqueue( item ); } Monitor.Pulse( workLock ); } } public void Shutdown() { Interlocked.Exchange( ref stop, 1 ); } private Queue workQueue; private Object workLock; private Thread[] threads; private int stop; } public class EntryPoint { static void WorkFunction() { Console.WriteLine( "WorkFunction() called on Thread {0}",Thread.CurrentThread.GetHashCode() ); //some long job double s = 0; for (int i = 0; i < 100000000; i++) s += Math.Sin(i); } static void Main() { CrudeThreadPool pool = new CrudeThreadPool(); for( int i = 0; i < 10; ++i ) { pool.SubmitWorkItem( new CrudeThreadPool.WorkDelegate( EntryPoint.WorkFunction) ); } pool.Shutdown(); } }

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  • Running 2 threads simultaneously

    - by lamsaitat
    In the case of an IM client. I have made 2 separate threads to handle sending packets (by std io) and receiving packets. The question is how to make these 2 threads run simultaneously so that I can keep prompting for input while at the same time be ready to receive packets at any time? I have already tried setting a timer but the data is always lost receiving.

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  • Queues And Wait Handles in C#

    - by Michael Covelli
    I've had the following code in my application for some years and have never seen an issue from it. while ((PendingOrders.Count > 0) || (WaitHandle.WaitAny(CommandEventArr) != 1)) { lock (PendingOrders) { if (PendingOrders.Count > 0) { fbo = PendingOrders.Dequeue(); } else { fbo = null; } } // Do Some Work if fbo is != null } Where CommandEventArr is made up of the NewOrderEvent (an auto reset event) and the ExitEvent (a manual reset event). But I just realized today that its not thread safe at all. If this thread gets interrupted right after the first (PendingOrder.Count 0) check has returned false. And then the other thread both enqueues an order and sets the NewOrderEvent before I get a chance to wait on it, the body of the while loop will never run. What's the usual pattern used with a Queue and an AutoResetEvent to fix this and do what I'm trying to do with the code above?

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  • Help with java threads or executors: Executing several MySQL selects, inserts and updates simmultane

    - by Martin
    Hi. I'm writing an application to analyse a MySQL database, and I need to execute several DMLs simmultaneously; for example: // In ResultSet rsA: Select * from A; rsA.beforeFirst(); while (rsA.next()) { id = rsA.getInt("id"); // Retrieve data from table B: Select * from B where B.Id=" + id; // Crunch some numbers using the data from B // Close resultset B } I'm declaring an array of data objects, each with its own Connection to the database, which in turn calls several methods for the data analysis. The problem is all threads use the same connection, thus all tasks throw exceptios: "Lock wait timeout exceeded; try restarting transaction" I believe there is a way to write the code in such a way that any given object has its own connection and executes the required tasks independent from any other object. For example: DataObject dataObject[0] = new DataObject(id[0]); DataObject dataObject[1] = new DataObject(id[1]); DataObject dataObject[2] = new DataObject(id[2]); ... DataObject dataObject[N] = new DataObject(id[N]); // The 'DataObject' class has its own connection to the database, // so each instance of the object should use its own connection. // It also has a "run" method, which contains all the tasks required. Executor ex = Executors.newFixedThreadPool(10); for(i=0;i<=N;i++) { ex.execute(dataObject[i]); } // Here where the problem is: Each instance creates a new connection, // but every DML from any of the objects is cluttered in just one connection // (in MySQL command line, "SHOW PROCESSLIST;" throws every connection, and all but // one are idle). Can you point me in the right direction? Thanks

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  • Java synchronizing static list ?

    - by JavaUser
    Hi, In a Java class , i am having a static list so this list is shared across all the objects of this class.The business logic in this class will run periodically which is invoked by some method with out passing instance parameters.Now I want to invoke this run method based on the list(I will add some vales into this list based on JMS) ,this list may empty sometimes and after finishing the run , i am emptying this list.Now my question is , whether I need to synchronize this list or not? Also let me know is there any other way to pass value in one object instance(Thread1) to other object instance (Thread2) other than having Static variable(static list)? Thx

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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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  • 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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  • Multi threading question..

    - by dotnet-practitioner
    I would like to invoke heavy duty method dowork on a separate thread and kill it if its taking longer than 3 seconds. Is there any problem with the following code? class Class1 { /// <summary> /// The main entry point for the application. /// </summary> [STAThread] static void Main(string[] args) { Console.WriteLine("starting new thread"); Thread t = new Thread(new ThreadStart(dowork)); t.Start(); DateTime start = DateTime.Now; TimeSpan span = DateTime.Now.Subtract(start); bool wait = true; while (wait == true) { if (span.Seconds > 3) { t.Abort(); wait = false; } span = DateTime.Now.Subtract(start); } Console.WriteLine("ending new thread after seconds = {0}", span.Seconds); Console.WriteLine("all done"); Console.ReadLine(); } static void dowork() { Console.WriteLine("doing heavy work inside hello"); Thread.Sleep(7000); Console.WriteLine("*** finished**** doing heavy work inside hello"); } }

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  • Can two or more threads iterate over the same List<t> without any problems?

    - by CodingCrapper
    Talking about System.Collections.Generic.List here. With example below can Method1 and Method2 execute and the same time, on different threads without any problems? Thanks class Test { private readonly List<MyData> _data; public Test() { _data = LoadData(); } private List<MyData> LoadData() { //Get data from dv. } public void Method1() { foreach (var list in _data) { //do something } } public void Method2() { foreach (var list in _data) { //do something } } }

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  • Waiting on threads

    - by Paul Reiners
    I have a method that contains the following (Java) code: doSomeThings(); doSomeOtherThings(); doSomeThings() creates some threads, each of which will run for only a finite amount of time. The problem is that I don't want doSomeOtherThings() to be called until all the threads launched by doSomeThings() are finished. (Also doSomeThings() will call methods that may launch new threads and so on. I don't want to execute doSomeOtherThings() until all these threads have finished.) This is because doSomeThings(), among other things will set myObject to null, while doSomeOtherThings() calls myObject.myMethod() and I do not want myObject to be null at that time. Is there some standard way of doing this kind of thing (in Java)?

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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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  • [C++] Start a thread using a method pointer

    - by Michael
    Hi ! I'm trying to develop a thread abstraction (POSIX thread and thread from the Windows API), and I would very much like it to be able to start them with a method pointer, and not a function pointer. What I would like to do is an abstraction of thread being a class with a pure virtual method "runThread", which would be implanted in the future threaded class. I don't know yet about the Windows thread, but to start a POSIX thread, you need a function pointer, and not a method pointer. And I can't manage to find a way to associate a method with an instance so it could work as a function. I probably just can't find the keywords (and I've been searching a lot), I think it's pretty much what Boost::Bind() does, so it must exist. Can you help me ?

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  • How to insert into data base using multi threading programming [closed]

    - by user1196650
    I am having a method and that method needs to do the following thing: It has to insert records into a database. No insert is done for the same table again. All inserts are into different tables. I need a multi threading logic which inserts the details into db using different threads. I am using oracle db and driver configuration and remaining stuff are perfect. Please help me with an efficient answer. Can anyone could provide me with a skeleton logic of the program.

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