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  • Command Not working in separate thread in J2me.

    - by RishiPatel
    I am creating a bluetooth application. I created a simple midlet with a exit command and i create a thread for finding the service and discovering the device. While doing so it displays a animated screen on which i added the parent commandListener for exit command. After successful connection both user is represented with greetings(Current screen calls the parent Display method setCurrent for displaying itself). This screen also have CommandListener set to the parent. Now i want to add few more commands. I Implemented the CommandLIstener Interface in this class, added few commands but the commands are not working. I dont whats wen wrong. I am giving u Code snippets to fully describle my issue : - package name Imports here public class MyMidlet extends MIDlet implements CommandListener { public CommandListener theListener; public Display theDisplay; public Command exitCommand; public MyMidlet() { // Retrieve the display for this MIDlet //Create the initial screen } public void startApp() throws MIDletStateChangeException { } public void pauseApp() { } public void destroyApp(boolean unconditional) { } public void commandAction(Command c, Displayable d) { // Determine if the exit command was selected if (c == exitCommand) { //End application here notifyDestroyed(); } else { //Start the new thread here } } } Now here is the code for the class which is invoked by the above midlet in a separate thread; package here; imports here public class MyService implements Runnable, CommandListener { private MyMidlet parent; private StreamConnection conn; private OutputStream output; private InputStream input; public Command sendCommand; private TextField messageToSend Form form; public BChatService(boolean isServer, BChatMidlet parent) { //some stuff here this.parent = parent; } public void run() { //functino for showing animation here try { input = conn.openInputStream(); output = conn.openOutputStream(); } catch (IOException e) { displayError("IO Error", "An error occurred while opening " + "the input and output streams" + "(IOException: " + e.getMessage() + ")"); try { conn.close(); } catch (Exception ex) { } return; } // Create the Form here when service is discoverd and greets the users Command sendCommand = new Command("Send", Command.ITEM, 2); exitCommand = new Command("Exit", Command.EXIT, 1); form.addCommand(exitCommand); form.addCommand(sendCommand); parent.theDisplay.setCurrent(form); form.setCommandListener(this); public void commandAction(Command c, Displayable d) { if (c == exitCommand) { // End the game parent.destroyApp(true); parent.notifyDestroyed(); } if(c == sendCommand) { form.append("SOme text here"); } } } When i select the Send command, the string doesnt append in form neither exit command works. What can be the possible cause for it?? I need to implement this functionality...Is there any other way to achieve this??

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  • C++ WIN32: Short multitasking example

    - by Con Current
    I searched for examples on how to create a simple multithreaded app that does something similar to this: #include <iostream> using namespace std; int myConcurrentFunction( ) { while( 1 ) { cout << "b" << endl; } } int main( ) { // Start a new thread for myConcurrentFunction while( 1 ) { cout << "a" << endl; } } How can I get the above to output a and b "randomly" by starting a new thread instead of just calling myConcurrentFunction normally? I mean: What is the minimal code for it? Is it really only one function I have to call? What files do I need to include? I use MSVC 2010, Win32

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  • Why aren't my threads start at the same time? Java

    - by Ada
    Hi, I have variable number of threads which are used for parallel downloading. I used this, for(int i = 0; i< sth; i++){ thrList.add(new myThread (parameters)); thrList.get(i).start(); thrList.get(i).join(); } I don't know why but they wait for each other to complete. When using threads, I am supposed get mixed print outs, since right then there are several threads running that code. However, when I print them out, they are always in order and one thread waits for the previous one to finish first. I only want them to join the main thread, not wait for each other. I noticed that when I measured time while downloading in parallel. How can I fix this? Why are they doing it in order? In my .java, there is MyThread class with run and there is Downloader class with static methods and variables. Would they be the cause of this? The static methods and variables? How can I fix this problem?

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  • Implementing deadlock condition

    - by Bhaskar
    I am trying to implementing deadlock condition but somehow I am not able to get it working. Both the threads Thread1 and Thread2 are entering in the run function but only one of them enters in Sub/Sum depending on who entered run first. Example : if Thread2 entered run first the it will call sub() and Thread1 never calls sum(). I have also added sleep time so that Thread2 sleeps before calling sum() and Thread1 gets enough time to enter Sum() but Thread1 never enters. public class ExploringThreads { public static void main(String[] args) { // TODO Auto-generated method stub threadexample a1 = new threadexample(); Thread t1 = new Thread(a1, "Thread1"); Thread t2 = new Thread(a1,"Thread2"); t1.start(); t2.start(); } } class threadexample implements Runnable{ public int a = 10; public void run(){ if(Thread.currentThread().getName().equals("Thread1")) sum(); else if(Thread.currentThread().getName().equals("Thread2")) sub(); } public synchronized void sum() { try { Thread.sleep(2000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } System.out.println(Thread.currentThread().getName()+"In Sum"); sub(); } public synchronized void sub() { try { Thread.sleep(2000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } System.out.println(Thread.currentThread().getName()+"In Sub"); sum(); } }

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  • Threaded Python port scanner

    - by Amnite
    I am having issues with a port scanner I'm editing to use threads. This is the basics for the original code: for i in range(0, 2000): s = socket(AF_INET, SOCK_STREAM) result = s.connect_ex((TargetIP, i)) if(result == 0) : c = "Port %d: OPEN\n" % (i,) s.close() This takes approx 33 minutes to complete. So I thought I'd thread it to make it run a little faster. This is my first threading project so it's nothing too extreme, but I've ran the following code for about an hour and get no exceptions yet no output. Am I just doing the threading wrong or what? import threading from socket import * import time a = 0 b = 0 c = "" d = "" def ScanLow(): global a global c for i in range(0, 1000): s = socket(AF_INET, SOCK_STREAM) result = s.connect_ex((TargetIP, i)) if(result == 0) : c = "Port %d: OPEN\n" % (i,) s.close() a += 1 def ScanHigh(): global b global d for i in range(1001, 2000): s = socket(AF_INET, SOCK_STREAM) result = s.connect_ex((TargetIP, i)) if(result == 0) : d = "Port %d: OPEN\n" % (i,) s.close() b += 1 Target = raw_input("Enter Host To Scan:") TargetIP = gethostbyname(Target) print "Start Scan On Host ", TargetIP Start = time.time() threading.Thread(target = ScanLow).start() threading.Thread(target = ScanHigh).start() e = a + b while e < 2000: f = raw_input() End = time.time() - Start print c print d print End g = raw_input()

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  • Thread is being killed by the OS

    - by Or.Ron
    I'm currently programming an app that extracts frames from a movie clip. I designed it so that the extraction will be done on a separate thread to prevent the application from freezing. The extraction process itself is taking a lot of resources, but works fine when used in the simulator. However, there are problems when building it for the iPad. When I perform another action (I'm telling my AV player to play while I extract frames), the thread unexpectedly stops working, and I believe it's being killed. I assume it's becauase I'm using a lot of resources, but not entirely sure. Here are my questions: 1. How can I tell if/why my thread stopping? 2. If it's really from over processing what should I do? I really need this action to be implemented. Heres some code im using: To create the thread: [NSThread detachNewThreadSelector:@selector(startReading) toTarget:self withObject:nil]; I'll post any information you need, Thanks so much! Update I'm using GCD now and it populates the threads for me. However the OS still kills the threads. I know exactly when is it happening. when i tell my [AVplayer play]; it kills the thread. This issue is only happening in the actual iPad and not on the simulator

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  • VB.net SyncLock Object

    - by Budius
    I always seen on SyncLock examples people using Private Lock1 As New Object ' declaration SyncLock Lock1 ' usage but why? In my specific case I'm locking a Queue to avoid problems on mult-threading Enqueueing and Dequeueing my data. Can I lock the Queue object itself, like this? Private cmdQueue As New Queue(Of QueueItem) ' declaration SyncLock cmdQueue ' usage Any help appreciated. Thanks.

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  • [Android] Thread Button sleep

    - by user557475
    Hello For my project,i´am trying to execute a Method every 10 seconds when i click a button "A" and it should stop when i click the button again (kind of on/off). this is what i reached :-/ : ButtonA.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { Handler handler = new Handler(); handler.postDelayed(new Runnable() { public void run() { showCurrentLocation(); Methodexecute(); } }, 10000); } } }); how can i repeat executing this method every 10 seconds until the button is clicked again. thanks

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  • XNA Multi-Thread Jitters

    - by Ice Phoenix
    Hi guys, brand new question. Just implemented multi-threading into my XNA game as it was unable to keep up with using 1 processor. MT is all implemented fine and everything, however the player seems to jitter all over the spot every now and then. I originally thought it was a loss of data between the update and render, but even when i did the player update in the render it did the same thing. It's not a memory/processor issue as i'm no where near maxing out my RAM or processors. It's strange aswell because none of the other entities in the game seem to have any of these issues. Any ideas at all??

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  • How do I best write my own background-working and communicatible (sending progress updates and getti

    - by Ivan
    I have to develop a class which can run it's own hard-coded task in a background thread and communicate with container class sending him progress updates and taking messages from it. I believe I am going to extend BackgroundWorker class but it looks a bit weird to extend and I haven't managed to find a good example wit Google. Can you share a link to a good example of solving such a task? Please don't offer placing a BackgroundWorker visually on a form and reading the standard tutorial, it's not for my case. Maybe I'd better not extend but encapsulate a BackgroundWorker, but I hardly understand how to use it outide WinForms designer either :-(

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  • Why is my BeginInvoke method not async?

    - by Petr
    Hi, In order to avoid freezing of GUI, I wanted to run method connecting to DB asynchronously. Therefore I have written this: DelegatLoginu dl = ConnectDB; IAsyncResult ar=dl.BeginInvoke(null, null); bool result = (bool)dl.EndInvoke(ar); But it is still freezing and I do not understand why - I though BeginInvoke assures that method it references is run in another thread. Thank you!

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  • Can I have multiple instance of the mandlebrot example in one program?

    - by yan bellavance
    Basically what I did is I took the Mandlebrot example and have 3 instances of it in my program. So the program would look like a mainwindow that has 3 mandlebrot widgets in it, one besides the other. Is it possible that GDB doesnt support debugging multiple intances of a classe that derives from qthread or is it thread-unsafe to do so? I don't have any problems at run-time but when I put breakpoints in a function called by the QThread run() function I get a segmentation fault. I can clearly see that the function doesn't complete before returning to the breakpoint ie I the program stops at the breakpoint, I step into the lines of codes one by one but after a couple of instructions another thread startS using the function(even though they are different instances).

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  • Persistance Queue Implementation

    - by Winter
    I was reading an article on Batch Processing in java over at JDJ http://java.sys-con.com/node/415321 . The article mentioned using a persistence queue as a Batch Updater instead of immediately sending an individual insert or update to the database. The author doesn't give a concrete example of this concept so I googled Persistence Queue but that didn't come up with much. Does anyone know of a good example of this?

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  • How to generate distinct random numbers per distinct threads in .NET?

    - by mark
    Dear ladies and sirs. I have to generate 19 bit random numbers. However, there is a constraint - two threads may not generate the same random number when running certain code. The simplest solution is lock the entire code. However, I would like to know if there is a non locking solution. I thought, I can incorporate ManagedThreadId within the produced random numbers, but the ManagedThreadId documentation on the Internet mentions that it may span the whole Int32 range. Unmanaged thread id seems to be limited to 11 bits, still this leaves me with just 8 truly random bits. Are there any other ways? Somehow to utilize the Thread Local Storage, may be? Thanks.

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  • Thread in android

    - by ravi adhikari
    Hi experts, I need some help as i am just calling a method in a thread. now what i want is wait for reply form getData() method only for 15 seconds. If it reply before 15 seconds it should be terminated otherwise after 15 seconds it should be terminated. The code is given below: boolean networkStatus; private Runnable runnable; private ProgressDialog m_ProgressDialog = null; private Runnable returnRes = new Runnable() { @Override public void run() { if(networkStatus){ setData(); m_ProgressDialog.dismiss(); } }; private void callGetdata(){ runnable = new Runnable() { @Override public void run() { networkStatus = getData(); runOnUiThread(returnRes); } }; Thread thread = new Thread(null, runnable, "MovetoBackground"); thread.start(); m_ProgressDialog = ProgressDialog.show(this, "", getString(R.string.loadMsg), true); }

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  • Qt: How to use QTimer to print a message to a QTextBrowser every 10 seconds?

    - by Aaron McKellar
    Hello, I have working at this for hours and cannot figure it out nor can I find any help online that works. Basically the gist of what I am trying to accomplish is to have a Qt GUI with a button and a QTextBrowser. When I push the button I want it to diplay a message and then keep printing this message every 10 seconds. I figured I would use QTimer because it makes sense to have a timer to diplay the message every 10 seconds. When I originally implemented this into my buttonClicked() SLOT it caused the program to freeze. I looked online for a solution and found QApplication::processEvents(). So basically in my function I had something like this: while(1) { QTimer *timer; connect(...) //omitted parameters for this example timer.start(10000); ui->diplay->append("Message"); while(timer.isActive()) { QApplication::processEvents() } } I figured it would break out of the timer.isActive() while loop but it won't it simply stays in there. So I figured this is a threading issue. So I figured out how to use QThreads but I still can't get it to work. Basically when I create a thread with a timer on it and the thread tells the timer to start, the program closes and the console says "The program has unexpectedly finished". There has to be an easy way to do this but my track record with Qt has always been that th

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  • Threads syncronization with ThreadPoolExecutor

    - by justme1
    I'm trying to implement some logic when I create main(father) thread witch executes several other threads. Then it waits for some condition which child threads creates. After condition is meet the father executes some more child threads. The problem that when I use wait/notify I have java.lang.IllegalMonitorStateException exception. Here is the code: public class MyExecutor { final static ArrayBlockingQueue<Runnable> queue = new ArrayBlockingQueue<Runnable>(10); final static ExecutorService svc = Executors.newFixedThreadPool(1); static final ThreadPoolExecutor threadPool = new ThreadPoolExecutor(5, 8, 10, TimeUnit.SECONDS, queue); public static void main(String[] args) throws InterruptedException { final MyExecutor me = new MyExecutor(); svc.execute(new Runnable() { public void run() { try { System.out.println("Main Thread"); me.execute(threadPool, 1); System.out.println("Main Thread waiting"); wait(); System.out.println("Main Thread notified"); me.execute(threadPool, 2); Thread.sleep(100); threadPool.shutdown(); threadPool.awaitTermination(20000, TimeUnit.SECONDS); } catch (InterruptedException e) { e.printStackTrace(); } } }); svc.shutdown(); svc.awaitTermination(10000, TimeUnit.SECONDS); System.out.println("Main Thread finished"); } public void execute(ThreadPoolExecutor tpe, final int id) { tpe.execute(new Runnable() { public void run() { try { System.out.println("Child Thread " + id); Thread.sleep(2000); System.out.println("Child Thread " + id + " finished"); notify(); } catch (InterruptedException e) { e.printStackTrace(); } } }); } } When I comment wait and notify line I have the following output: Main Thread Main Thread waiting Main Thread notified Child Thread 1 Child Thread 2 Child Thread 1 finished Child Thread 2 finished Main Thread finished

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  • Cocoa multhithreads, locks don't work

    - by Igor
    I have a threadMethod which shows in console robotMotorsStatus every 0.5 sec. But when I try to change robotMotorsStatus in changeRobotStatus method I receive an exception. Where I need to put locks in that program. #import "AppController.h" @implementation AppController extern char *robotMotorsStatus; - (IBAction)runThread:(id)sender { [self performSelectorInBackground:@selector(threadMethod) withObject:nil]; } - (void)threadMethod { char string_to_send[]="QFF001100\r"; //String prepared to the port sending (first inintialization) string_to_send[7] = robotMotorsStatus[0]; string_to_send[8] = robotMotorsStatus[1]; while(1){ [theLock lock]; usleep(500000); NSLog (@"Robot status %s", robotMotorsStatus); [theLock unlock]; } } - (IBAction)changeRobotStatus:(id)sender { robotMotorsStatus[0]='1'; }

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  • Do I need to using locking against integers in c++ threads

    - by Shane MacLaughlin
    The title says it all really. If I am accessing a single integer type (e.g. long, int, bool, etc...) in multiple threads, do I need to use a synchronisation mechanism such as a mutex to lock them. My understanding is that as atomic types, I don't need to lock access to a single thread, but I see a lot of code out there that does use locking. Profiling such code shows that there is a significant performance hit for using locks, so I'd rather not. So if the item I'm accessing corresponds to a bus width integer (e.g. 4 bytes on a 32 bit processor) do I need to lock access to it when it is being used across multiple threads? Put another way, if thread A is writing to integer variable X at the same time as thread B is reading from the same variable, is it possible that thread B could end up a few bytes of the previous value mixed in with a few bytes of the value being written? Is this architecture dependent, e.g. ok for 4 byte integers on 32 bit systems but unsafe on 8 byte integers on 64 bit systems? Edit: Just saw this related post which helps a fair bit.

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  • Debug.writeline locks

    - by Carra
    My program frequently stops with a deadlock. When I do a break-all and look at the threads I see that three threads are stuck in our logging function: public class Logging { public static void WriteClientLog(LogLevel logLevel, string message) { #if DEBUG System.Diagnostics.Debug.WriteLine(String.Format("{0} {1}", DateTime.Now.ToString("HH:mm:ss"), message)); //LOCK #endif //...Log4net logging } } If I let the program continue the threads are still stuck on that line. I can't see where this can lock. The debug class, string class & datetime class seem to be thread safe. The error goes away when I remove the "#if DEBUG System... #endif" code but I'm curious why this behavior happens. Thread one: public void CleanCache() { Logging.WriteClientLog(LogLevel.Debug, "Start clean cache.");//Stuck } Thread two: private void AliveThread() { Logging.WriteClientLog(LogLevel.Debug, "Check connection");//Stuck }

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