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  • PyQt4 plugin in c++ application

    - by veverica17
    How is it posible to load python script as plugin in qt based application? The basic idea would be to make a class in c++ class b { virtual void method1(); virtual void method2(); } and 'somehow' inherit it in python like class c(b): def method1: #do something def method2: #do something I need to be able to modify the gui from python( add buttons to some widgets made in c++ with qt ). Basicaly something similiar to (gedit, blender, etc) plugin architecture with qt

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  • How to handle error on other thread?

    - by markattwood
    Hi, I'm trying to handle errors that have occurred on other threads the .NET CF program is like below: static void Main() { Thread t = new Thread(Start); t.Start(); ... } void Start() { ... Exception here } In my situation, putting try catch in the Start method is impossible. How can I handle it in the global code?

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  • linux process scheduling delayed for long time

    - by Medicine
    I have done strace on my multi-threaded c++ application running on linux after couple hours of running, none of the threads got run, for about 12 seconds. I have seen that the unfinished select system call which is called with a timeout was unfinished before the thread was suspended, reported after it resumed that, it took 11.x seconds for the operation to finish. This is clear indication that the process got starved for a long time. All threads in the process are created with default scheduling policy(SCHED_OTHER) of linux and default priority. There are another 5 similar apps running on the same box which are also heavy I/O bound like this app due to heavy data received on the socket. But most of the time, this app is getting scheduled delay. The other apps are created with same sched policy and priority as this i.e. the defaults. why is only this process gets blocked almost all of the time? Could it be because this process is more I/O intensive as in more busy due to may be higher rates of data? So, the linux dynamic priority adjusting in play here which pushed this process down?

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  • IS ResultSet thread safe

    - by javatraniee
    Is ResultSet Thread safe? My question arises because in this i have used a different statement for each query i have delsared a ResultSet as an local variable but it gives me a error of Operation not allowed after ResultSet is closed. But my statements are working as i'm using the statements in insert and delete query.I have commented the ResultSet part and have not got the error !! The source code of my program can be referd to , in my earlier Question .

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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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  • New to threading in C#, can you make thread methods generic and what are the dangers?

    - by ibarczewski
    Hey all, I'm just now starting to get into the idea of threading, and wanted to know if I could make this more abstract. Both foo and bar derive methods from a base class, so I'd like to pass in one or the other and be able to do work using a method that was derived. I'd also like to know how you properly name threads and the methods inside threads. if (ChkFoo.Checked) { Thread fooThread = new Thread(new ThreadStart(this.ThreadedFooMethod)); fooThread.Start(); } if (ChkBar.Checked) { Thread barThread = new Thread(new ThreadStart(this.ThreadedBarMethod)); barThread.Start(); } . . . public void ThreadedFooMethod() { Foo newFoo = new Foo(); //Do work on newFoo } public void ThreadedBarMethod() { Bar newBar = new Bar(); //Do similar work } Thanks all!

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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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  • When should ThreadLocal be used instead of Thread.SetData/Thread.GetData?

    - by Jon Ediger
    Prior to .net 4.0, I implemented a solution using named data slots in System.Threading.Thread. Now, in .net 4.0, there is the idea of ThreadLocal. How does ThreadLocal usage compare to named data slots? Does the ThreadLocal value get inherited by children threads? Is the idea that ThreadLocal is a simplified version of using named data slots? An example of some stuff using named data slots follows. Could this be simplified through use of ThreadLocal, and would it retain the same properties as the named data slots? public static void SetSliceName(string slice) { System.Threading.Thread.SetData(System.Threading.Thread.GetNamedDataSlot(SliceVariable), slice); } public static string GetSliceName(bool errorIfNotFound) { var slice = System.Threading.Thread.GetData(System.Threading.Thread.GetNamedDataSlot(SliceVariable)) as string; if (errorIfNotFound && string.IsNullOrEmpty(slice)) {throw new ConfigurationErrorsException("Server slice name not configured.");} return slice; }

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  • how do I repaint an applet while moving a sprite?

    - by Nagrom_17
    I have a little java applet where I create 2 threads, one thread repaints and the other moves an image from a point to where the user clicks. The problem is that when I call the move function it loops until the image is where the user clicks but it wont repaint until I break out of the loop even though the thread doing the moving and the thread doing the painting are separate. shortened version of key points: my program is an applet using the paint() method I have 2 threads one moves an image and the other paints that image when I am moving the image it is in a while loop the painting thread is still calling repaint() but that is as far as the call goes, it never repaints thank you for your time.

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  • Create table class as a singleton

    - by Mark
    I got a class that I use as a table. This class got an array of 16 row classes. These row classes all have 6 double variables. The values of these rows are set once and never change. Would it be a good practice to make this table a singleton? The advantage is that it cost less memory, but the table will be called from multiple threads so I have to synchronize my code which way cause a bit slower application. However lookups in this table are probably a very small portion of the total code that is executed. EDIT: This is my code, are there better ways to do this or is this a good practice? Removed synchronized keyword according to recommendations in this question. final class HalfTimeTable { private HalfTimeRow[] table = new HalfTimeRow[16]; private static final HalfTimeTable instance = new HalfTimeTable(); private HalfTimeTable() { if (instance != null) { throw new IllegalStateException("Already instantiated"); } table[0] = new HalfTimeRow(4.0, 1.2599, 0.5050, 1.5, 1.7435, 0.1911); table[1] = new HalfTimeRow(8.0, 1.0000, 0.6514, 3.0, 1.3838, 0.4295); //etc } @Override @Deprecated public Object clone() throws CloneNotSupportedException { throw new CloneNotSupportedException(); } public static HalfTimeTable getInstance() { return instance; } public HalfTimeRow getRow(int rownumber) { return table[rownumber]; } }

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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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  • 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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  • Is it safe to read global data from multiple threads?

    - by user362515
    The scenario is as follows: Create an instance of a class (std::map) and sore it as global variable. Spawn threads. Threads read and use the same global instance of the class All spawned threads quit Global class instance is destroyed No mutex, no thread modifies the global class instance. Is this OK? Thank You

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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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  • Reading from a very large table using multiple threads (Java ) and writing them to a single file

    - by user2534926
    I am currently facing a situation where i have a table with almost 80 millions data and i have to take a dump of that table and store it into a csv file. Currently i am using a not so professional approach( with a perl script+DBI interface , printing the values to stdout and redirecting to a csv file). Now i am planning to use java threading approach. Can you suggest a way forward. Thanks in advance

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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 address thread-safety of service data used for maintaining static local variables in C++?

    - by sharptooth
    Consider the following scenario. We have a C++ function with a static local variable: void function() { static int variable = obtain(); //blahblablah } the function needs to be called from multiple threads concurrently, so we add a critical section to avoid concurrent access to the static local: void functionThreadSafe() { CriticalSectionLockClass lock( criticalSection ); static int variable = obtain(); //blahblablah } but will this be enough? I mean there's some magic that makes the variable being initialized no more than once. So there's some service data maintained by the runtime that indicates whether each static local has already been initialized. Will the critical section in the above code protect that service data as well? Is any extra protection required for this scenario?

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  • C# 4.0 how to pass variables to threads?

    - by Aviatrix
    How would i pass some parameters to a new thread that runs a function from another class ? What i'm trying to do is to pass an array or multiple variables to a function that sits in another class and its called by a new thread. i have tried to do it like this Functions functions = new Functions(); string[] data; Thread th = new Thread(new ParameterizedThreadStart(functions.Post())); th.Start(data); but it shows error "No overload for method 'Post' takes 0 arguments" Any ideas ?

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  • Is it possible to put a form control on its own thread?

    - by BVernon
    I'm using a DataGridView and some operations that I do cause it to become unresponsive for periods of time. Normally I would put data processing in its own thread to make the form more responsive, but in this case it's the DataGridView itself that's taking so long. This leads me to wonder whether it's possible to have the main form on one thread and the DataGridView on another thread so it doesn't prevent the main form from responding. I completely understand that doing so is probably not 'safe' and likely opens up a can of worms that makes it hardly worth trying and I fully expect this post will be getting down votes for merely suggesting such a ridiculous idea. Is this possible? And if so how would you go about it?

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  • run two thread at the same time in java

    - by user1805005
    i have used timertask to schedule my java program. now when the run method of timertask is in process, i want to run two threads which run at the same time and do different functions. here is my code.. please help me.. import java.util.Calendar; import java.util.Date; import java.util.Timer; import java.util.TimerTask; public class timercheck extends TimerTask{ // my first thread Thread t1 = new Thread(){ public void run(){ for(int i = 1;i <= 10;i++) { System.out.println(i); } } }; // my second thread Thread t2 = new Thread(){ public void run(){ for(int i = 11;i <= 20;i++) { System.out.println(i); } } }; public static void main(String[] args){ long ONCE_PER_DAY = 1000*60*60*24; Calendar calendar = Calendar.getInstance(); calendar.set(Calendar.HOUR_OF_DAY, 12); calendar.set(Calendar.MINUTE, 05); calendar.set(Calendar.SECOND, 00); Date time = calendar.getTime(); TimerTask check = new timercheck(); Timer timer = new Timer(); timer.scheduleAtFixedRate(check, time ,ONCE_PER_DAY); } @Override // run method of timer task public void run() { t1.start(); t2.start(); } }

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