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  • Is PThread a good choice for multi-platorm C/C++ multi-threading program?

    - by RogerV
    Been doing mostly Java and smattering of .NET for last five years and haven't written any significant C or C++ during that time. So have been away from that scene for a while. If I want to write a C or C++ program today that does some multi-threading and is source code portable across Windows, Mac OS X, and Linux/Unix - is PThread a good choice? The C or C++ code won't be doing any GUI, so won't need to worry with any of that. For the Windows platform, I don't want to bring a lot of Unix baggage, though, in terms of unix emulation runtime libraries. Would prefer a PThread API for Windows that is a thin-as-possible wrapper over existing Windows threading APIs. ADDENDUM EDIT: Am leaning toward going with boost:thread - I also want to be able to use C++ try/catch exception handling too. And even though my program will be rather minimal and not particularly OOPish, I like to encapsulate using class and namespace - as opposed to C disembodied functions.

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  • Easy Threading in WPF

    - by Sandeep Bansal
    Hi everyone, I've been reading a lot about threading in C#, WPF and Silverlight but can't get it to work. My main problem is I have the _load (_Initialized) action and it has a lot of object creation and along with that I have timers working doing different things, this causes the startup time of the program to be very slow and obviously causes the UI to hang and it isn't a good thing for deploying to a lot of users. My timers change values of labels and textfields but having them do that on another thread is an obvious no go. So can someone give me some examples on how to achieve what I need to do? Thanks

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  • Forcing an app to run single core only?

    - by Kevin
    I have this strange issue with some third party DLL's. The third party provider references some open source DLL's that have a memory exception whenever I try to use a certain method. This issue does not appear when the app is run on a single core machine, but obviously we cannot assume a user will have that. Is there a way to force an app, or even better yet a referenced DLL to run on a single core? Any other way to possibly fix this? Getting the third party to rebuild the OS dll's is apparently out of the question (its a bit of a sore spot with me currently :) ) so I have to handle it myself or just forget about providing this functionality.

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  • How do I make this Java code operate properly? [Multi-threaded, race condition]

    - by Fixee
    I got this code from a student, and it does not work properly because of a race condition involving x++ and x--. He added synchronized to the run() method trying to get rid of this bug, but obviously this only excludes threads from entering run() on the same object (which was never a problem in the first place) but doesn't prevent independent objects from updating the same static variable x at the same time. public class DataRace implements Runnable { static volatile int x; public synchronized void run() { for (int i = 0; i < 10000; i++) { x++; x--; } } public static void main(String[] args) throws Exception { Thread [] threads = new Thread[100]; for (int i = 0; i < threads.length; i++) threads[i] = new Thread(new DataRace()); for (int i = 0; i < threads.length; i++) threads[i].start(); for (int i = 0; i < threads.length; i++) threads[i].join(); System.out.println(x); // x not always 0! } } Since we cannot synchronize on x (because it is primitive), the best solution I can think of is to create a new static object like static String lock = ""; and enclose the x++ and x-- within a synchronized block, locking on lock. But this seems really awkward. Is there a better way?

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  • Java Socket - how to catch Exception of BufferedReader.readline()

    - by Hasan Tahsin
    I have a Thread (let's say T1) which reads data from socket: public void run() { while (running) { try { BufferedReader reader = new BufferedReader( new InputStreamReader(socket.getInputStream()) ); String input = reader.readLine(); } catch (IOException e) { e.printStackTrace(); } } } Another Thread (lets say T2) try to finish the program in one of its method. Therefore T2 does the following: T1.running = false; socket.close(); Here is this scenario for which i couldn't find a solution: T1 is active and waiting for some input to read i.e. blocking. context switching T2 is active and sets running to false, closes the socket context switching because T1 was blocking and T2 closed the socket, T1 throws an Exception. What i want is to catch this SocketException. i can't put a try/catch(SocketException) in T1.run(). So how can i catch it in T1's running-method? If it's not possible to catch it in T1's running, then how can i catch it elsewhere? PS: "Another question about the Thread Debugging" Normally when i debug the code step by step, i lose the 'active running line' on a context switch. Let's say i'm in line 20 of T1, context switch happens, let's assume the program continues from the 30.line of T2, but the debugger does not go/show to the 30.line of T2, instead the 'active running line' vanishes. So i lose the control over the code. I use Eclipse for Java and Visual Studio for C#. So what is the best way to track the code while debugging on a context switch ?

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  • [gtk+] run function in another thread than gui

    - by sterh
    Hello, I have simple C/gtk+ application. I have function in this app which load image in gtkimageview widget: gboolean main_win_open( MainWin* mw, const char* file_path) { ... //loading and displaing image in gtkimageview ... } The loading image is work, but i need to run this function in another thread then main gui form; I have function: void* argument_thread(void *args) { Data *data = (Data*)args; gdk_threads_enter(); main_win_open (data->win,data->argv); gdk_threads_leave(); } Data it's structure for main_win_open function arguments: typedef struct _Data { MainWin *win; char* argv; } Data; Then in main function i create thread and run it: int main(int argc, char** argv) { GError* err; GThread* thread; Data data; MainWin *win; // init thread support if(!g_thread_supported()) g_thread_init(NULL); gdk_threads_init(); // init GTK+ gtk_init (&argc, &argv); win = (MainWin*)main_win_new(); gtk_widget_show(GTK_WIDGET(win)); data.win = win; data.argv = argv[1]; if (argc == 2) { thread = g_thread_create((GThreadFunc)argument_thread,&data,FALSE, &err); } gdk_threads_enter(); gtk_main(); gdk_threads_leave(); } But when i try to run app from command line and try to load big-size image, gui is blocking. What's wrong? Thank you.

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  • Referenced assembly won't load in new thread on IIS 7

    - by DanielC
    I have a process in which a user uploads a file to a web site where the file is then processed and uploaded into the database. The process of validating the file could take several minutes so as soon as the file is uploaded I create a new thread and I do my processing on this second thread. This works great on my local machine but doesn't work at all on my IIS 7 test server. After some investigating I found the problem is that the process is trying to load a reference to Castle and it can't find the DLL. I have a copy of Castle DLLs in my bin and it works elsewhere in my app. I ran Fuslog and discovered that it is trying to load castle from the wrong location. It is trying to load from c:/windows/system32/inetsrv/. It appears that under IIS 7 the second thread is executing in a different context or something. So the question is what can I do to get it to find Castle in the application BIN folder?

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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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  • Should I use multiple threads in this situation? [Ruby]

    - by mr popo
    I'm opening multiple files and processing them, one line at a time. The files contain tokens separating the data, such that sometimes the processing of one file may have to wait for others to catch up to that same token. I was doing this initially with only one thread and an array indicating with true/false if the file should be read in the current iteration or if it should wait for some of the others to catch up. Would using threads make this simpler? More efficient? Does Ruby have a mechanism for this?

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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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  • "Multi-threading" w/ NSTimers in an iPhone app

    - by MrDatabase
    Say I have two NSTimers in my iPhone app: timer1 and timer2. timer1 calls function1 30 times per second and timer2 calls function2 30 times per second. Assume these two functions are reading and updating the same integer variables. Are there any "multi-threading" issues here? If not how does iPhone OS handle the execution of the two functions (in general)?

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  • Thread too slow. Better way to execute code (Android AndEngine)?

    - by rphello101
    I'm developing a game where the user creates sprites with every touch. I then have a thread run to check to see if those sprites collide with any others. The problem is, if I tap too quickly, I cause a null pointer exception error. I believe it's because I'm tapping faster than my thread is running. This is the thread I have: public class grow implements Runnable{ public grow(Sprite sprite){ } @Override public void run() { float radf, rads; //fill radius/stationary radius float fx=0, fy=0, sx, sy; while(down){ if(spriteC[spriteNum].active){ spriteC[spriteNum].sprite.setScale(spriteC[spriteNum].scale += 0.001); if(spriteC[spriteNum].sprite.collidesWith(ground)||spriteC[spriteNum].sprite.collidesWith(roof)|| spriteC[spriteNum].sprite.collidesWith(left)||spriteC[spriteNum].sprite.collidesWith(right)){ down = false; spriteC[spriteNum].active=false; yourScene.unregisterTouchArea(spriteC[spriteNum].sprite); } fx = spriteC[spriteNum].sprite.getX(); fy = spriteC[spriteNum].sprite.getY(); radf=spriteC[spriteNum].sprite.getHeightScaled()/2; Log.e("F"+Float.toString(fx),Float.toString(fy)); if(spriteNum>0) for(int x=0;x<spriteNum;x++){ rads=spriteC[x].sprite.getHeightScaled()/2; sx = spriteC[x].body.getWorldCenter().x * 32; sy = spriteC[x].body.getWorldCenter().y * 32; Log.e("S"+Float.toString(sx),Float.toString(sy)); Log.e(Float.toString((float) Math.sqrt(Math.pow((fx-sx),2)+Math.pow((fy-sy),2))),Float.toString((radf+rads))); if(Math.sqrt(Math.pow((fx-sx),2)+Math.pow((fy-sy),2))<(radf+rads)){ down = false; spriteC[spriteNum].active=false; yourScene.unregisterTouchArea(spriteC[spriteNum].sprite); Log.e("Collided",Boolean.toString(down)); } } } } spriteC[spriteNum].body = PhysicsFactory.createCircleBody(mPhysicsWorld, spriteC[spriteNum].sprite, BodyType.DynamicBody, FIXTURE_DEF); mPhysicsWorld.registerPhysicsConnector(new PhysicsConnector(spriteC[spriteNum].sprite, spriteC[spriteNum].body, true, true)); } } Better solution anyone? I know there is something to do with a handler, but I don't exactly know what that is or how to use one.

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  • Is there a way to reliably detect the total number of CPU cores?

    - by John Sheares
    I need a reliable way to detect how many CPU cores are on a computer. I am creating a numerically intense simulation C# application and want to create the maximum number of running threads as cores. I have tried many of the methods suggested around the internet like Environment.ProcessorCount, using WMI, this code: http://blogs.adamsoftware.net/Engine/DeterminingthenumberofphysicalCPUsonWindows.aspx. None of them seem to think a AMD X2 has two cores. Any ideas?

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  • Application window sent behind other windows on closing different thread (C#)

    - by david.murrant
    I'm writing a Windows Forms Application in C#.NET On startup, the application displays a splash screen which is running in a separate thread. Whilst the splash screen is showing, the main application is initialising. Once the main application has finished initialising, the main form of the application is displayed, and the splash screen still shows over the top. Everything so far is as expected. Then, the Splash screen is closed, which causes that thread to exit. For some reason, at the point, the main application windows gets sent behind all other open Windows, notably the Windows Explorer window where you clicked the .exe file to run the application in the first place! What could be causing the windows to suddenly jump "behind" like this?

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  • Does SetThreadPriority cause thread reschedulling?

    - by Suma
    Consider following situation, assuming single CPU system: thread A is running with a priority THREAD_PRIORITY_NORMAL, signals event E thread B with a priority THREAD_PRIORITY_LOWEST is waiting for an event E (Note: at this point the thread is not scheduled because it is runnable, but A is higher priority and runnable as well) thread A calls SetThreadPriority(B, THREAD_PRIORITY_ABOVE_NORMAL) Is thread B re-scheduled immediately to run, or is thread A allowed to continue until current time-slice is over, and B is scheduled only once a new time-slice has begun? I would be interested to know the answer for WinXP, Vista and Win7, if possible. Note: the scenario above is simplified from my real world code, where multiple threads are running on multiple cores, but the main object of the question stays: does SetThreadPriority cause thread scheduling to happen?

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  • C# Anyway to detect if an object is locked.

    - by scope-creep
    Hi, Is their anyway to determine if a object is locked in c#. I have the unenviable position, through design where i'm reading from a queue inside a class, and I need to dump the contents into a collection in the class. But that collection is also read/write from an interface outside the class. So obviously their may be a case when the collection is being written to, as the same time i want to write to it. I could program round it, say using delegate but it would be ugly. Bob.

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  • Multithreaded SDL error in C++

    - by wyatt
    I'm building a program in C++, using SDL, and am occasionally receiving this error: * glibc detected * ./assistant: double free or corruption (!prev) It's difficult to replicate, so I can't find exactly what's causing it, but I just added a second thread to the program, and neither thread run on its own seems to cause the error. The threads don't share any variables, though they both run the functions SDL_BlitSurface and SDL_Flip. Could running these concurrently throw up such an error, or am I barking up the wrong tree? If this is the cause, should I simply throw a mutex around all SDL calls? Thanks

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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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  • 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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  • Threading in C#

    - by j-t-s
    Hi All Just looking for something ultra simple. I need to spawn a method off to a new thread. I don't care when or how it ends. Can somebody please help me with this? Thank you

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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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  • In C# is there a thread scheduler for long running threads?

    - by LogicMagic
    Hi, Our scenario is a network scanner. It connects to a set of hosts and scans them in parallel for a while using low priority background threads. I want to be able to schedule lots of work but only have any given say ten or whatever number of hosts scanned in parallel. Even if I create my own threads, the many callbacks and other asynchronous goodness uses the ThreadPool and I end up running out of resources. I should look at MonoTorrent... If I use THE ThreadPool, can I limit my application to some number that will leave enough for the rest of the application to Run smoothly? Is there a threadpool that I can initialize to n long lived threads?

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