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  • Have main thread wait for a boost thread complete a task (but not finish).

    - by JAKE6459
    I have found plenty on making one thread wait for another to finish executing before continuing, but that is not what I wanted to do. I am not very familiar with using any multi-threading apis but right now I'm trying to learn boost. My situation is that I am using my main thread (the starting one from int main()) to create an instance of a class that is in charge of interacting with the main GUI. A class function is then called that creates a boost thread which in turn creates the GUI and runs the message pump. The thing I want to do is when my main thread calls the classes member function to create the GUI, I don't want that function to return until I tell it to from the newly created thread. This way my main thread can't continue and call more functions from the GUI class that interact with the GUI thread until that thread has completed GUI creation and entered the message loop. I think I may be able to figure it out if it was multiple boost thread objects interacting with each other, but when it is the main thread (non-boost object) interacting with a boost thread object, I get lost. Eventually I want a loop in my main thread to call a class function (among other tasks) to check if the user as entered any new input into the GUI (buy any changes detected by the message loop being updated into a struct and changing a bool to tell the main thread in the class function a change has occurred). Any suggestions for any of this would be greatly appreciated. This is the member function called by the main thread. int ANNGUI::CreateGUI() { GUIMain = new Main(); GUIThread = new boost::thread(boost::bind(&Main::MainThreadFunc, GUIMain)); return 0; }; This is the boost thread starting function. void Main::MainThreadFunc() { ANNVariables = new GUIVariables; WndProc = new WindowProcedure; ANNWindowsClass = new WindowsClass(ANNVariables, WndProc); ANNWindow = new MainWindow(ANNVariables); GUIMessagePump = new MessagePump; ANNWindow-ShowWindows(); while(true) { GUIMessagePump-ProcessMessage(); } }; BTW, everything compiles fine and when I run it, it works I just put a sleep() in the main thread so I can play with the GUI a little.

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  • Simulators for thread scheduling on multicore

    - by shijie xu
    I am seeking a simulator for thread scheduling at multi-core architecture, that is mapping threads to the cores at runtime. During runtime, simulator collects overall cache and IPC statistics. I checked below simulators, but seems there are not sufficient for me: Simplescalar: A simulator only for single core. SESC: multiprocessor simulator with detailed power, thermal, and performance models, QSim: provides instruction-level control of the emulated environment and detailed information about the executing instruction stream. It seems both SESC and QSim supports instructions scheduling instead of thread scheduling on the cores? Anyone can help provide some clues or share experience for this part?

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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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  • 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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  • 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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  • 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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  • 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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  • 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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  • 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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  • 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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  • Iterators over a LInked List in a Game in Java

    - by Matthew
    I am using OpenGl in android and they have a callback method called draw that gets called with out my control. (As fast as the device can handle if I am not mistaken) I have a list of "GameObjects" that have a .draw method and a .update method. I have two different threads that handle each of those. So, the question is, can I declare two different iterators in two different methods in two different threads that iterate over the same Linked List? If so, do I simply declare ListIterator<GameObject> l = objets.listIterator() each time I want a new iterator and it won't interfere with other iterators?

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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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  • Multithreaded Applications

    - by j-t-s
    Hi All I have been reading the articles on MSDN, but my mind is dead (this usually happens when I read MSDN (No offense MSDN, but your articles confuse me at times.)), and I'm trying to do some "background work" in may app, but not sure how. It's just a single method. But the application hangs, and I have to wait up to 1 - 3 minutes for it to become ...unhanged? Are there any simple examples that are laying 'roun online somewhere that I can have a look at/play around with? Thank you all

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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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  • 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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  • 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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  • 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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  • 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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  • 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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  • Is it save 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 it ok? Thank You

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