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  • Minimizing Java Thread Context Switching Overhead

    - by binil
    I have a Java application running on Sun 1.6 32-bit VM/Solaris 10 (x86)/Nahelem 8-core(2 threads per core). A specific usecase in the application is to respond to some external message. In my performance test environment, when I prepare and send the response in the same thread that receives the external input, I get about 50 us advantage than when I hand off the message to a separate thread to send the response. I use a ThreadPoolExecutor with a SynchronousQueue to do the handoff. In your experience what is the acceptable delay between scheduling a task to a thread pool and it getting picked up for execution? What ideas had worked for you in the past to try improve this?

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  • Sleep a thread until an event is attended in another thread from a different class

    - by Afro Genius
    I have an application that fires 2 threads, the 1st launches another class to do some processing which in turn launches a 3rd class to do yet more processing. The 2nd thread in the main class should wait until some event in the 3rd class completes before it performs its job. How can this be achieved? I had tried implementing a wait/notify to share a lock object between the two threads but technically this will not work as I found the hard way. Can I share a lock between classes? Note, an instance of the 3rd class is declared in the 1st class and passed as parameter to the 2nd class. Also I tried creating boolean value in 3rd class that tells when event is complete then poll 2nd thread till this value is true. This worked but is not very desirable. Also is actionListner a better approach to this problem?

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  • Threadpool with pasistant worker instances

    - by Matt Smokey-waters Holmes
    So basically what im trying to do is queue up tasks in a thread pool to be executed as soon as a worker becomes free, i have found various examples of this but in all cases the examples have been setup to use a new Worker instance for each job, i want persistent workers. Im trying to make a ftp backup tool, i have it working but because of the limitations of a single connection it is slow. What i ideally want to do is have a single connection for scanning directories and building up a file list then four workers to download said files. Here is an example of my worker /** * FTP Worker */ public class Worker implements Runnable { protected FTPClient _ftp; // Connection details protected String _host = ""; protected String _user = ""; protected String _pass = ""; // worker status protected boolean _working = false; public Worker(String host, String user, String pass) { this._host = host; this._user = user; this._pass = pass; } // Check if the worker is in use public boolean inUse() { return this._working; } @Override public void run() { this._ftp = new FTPClient(); this._connect(); } // Download a file from the ftp server public boolean download(String base, String path, String file) { this._working = true; boolean outcome = true; //create directory if not exists File pathDir = new File(base + path); if (!pathDir.exists()) { pathDir.mkdirs(); } //download file try { OutputStream output = new FileOutputStream(base + path + file); this._ftp.retrieveFile(file, output); output.close(); } catch (Exception e) { outcome = false; } finally { this._working = false; return outcome; } } // Connect to the server protected boolean _connect() { try { this._ftp.connect(this._host); this._ftp.login(this._user, this._pass); } catch (Exception e) { return false; } return this._ftp.isConnected(); } // Disconnect from the server protected void _disconnect() { try { this._ftp.disconnect(); } catch (Exception e) { /* do nothing */ } } } and basically i want to be able to call Worker.download(...) for each task in a queue whenever a worker becomes available without having to create a new connection to the ftp server for each download Any help would be appreciated as iv'e never used threads before and I'm going round in circles at the moment

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  • thread destructors in C++0x vs boost

    - by Abruzzo Forte e Gentile
    Hi All These days I am reading the pdf Designing MT programs . It explains that the user MUST explicitly call detach() on an object of class std::thread in C++0x before that object gets out of scope. If you don't call it std::terminate() will be called and the application will die. I usually use boost::thread for threading in C++. Correct me if I am wrong but a boost::thread object detaches automatically when it get out of scope. Is seems to me that the boost approach follow a RAII principle and the std doesn't. Do you know if there is some particular reason for this? Kind Regards AFG

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  • Thread help with Android game

    - by Ciph3rzer0
    I need some help dealing with three Threads in Android One thread is the main thread, the other is the GLThread, and the other is a WorkerThread I created to update the game state. The problem I have is they all need to access the same LinkedList of game objects. Both the GLThread and my WorkerThread only read from the LinkedList, so no problem there, but occasionally I have the main thread adding in another game object to the list. How can I manage this? I tried using synchronized in front of the functions involved but it really slows down the application. For some reason, just catching the errors and not rendering or updating the game state that frame, causes it to start lagging permanently. Anyone have any great ideas?

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  • VC++ - Asynchronous Thread

    - by JVNR
    I am working on VC++ project, in that my application process a file from input path and generates 3 output "*.DAT" files in the destination path. I will FTP these DAT file to the destination server. After FTP, I need to delete only two output .DAT files the folder. I am able to delete those files, because there one Asynchronous thread running behind the process. Since the thread is running, while deleting it says, "Cannot delete, the file is used by another person". I need to stop that thread and delete the files. Multiple files can also be taken from the input path to process. Please help me in resolving this issue. Its very high priority issue for me. Please help me ASAP.

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  • Update UI in the main activity through handler in a thread (Android)

    - by Hrk
    Hello, I try to make several connection in a class and update the multiple progressbar in the main screen. But I've got the following error trying to use thread in android : Code: 05-06 13:13:11.092: ERROR/ConnectionManager(22854): ERROR:Can't create handler inside thread that has not called Looper.prepare() Here is a small part of my code in the main Activity public class Act_Main extends ListActivity { private ConnectionManager cm; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Set up the window layout requestWindowFeature(Window.FEATURE_CUSTOM_TITLE); setContentView(R.layout.main); getWindow().setFeatureInt(Window.FEATURE_CUSTOM_TITLE, R.layout.custom_title); } public void startConnection() { //open DB connection db = new DBAdapter(getApplicationContext()); db.open(); cm = new ConnectionManager(handler, db); showDialog(DIALOG_PROGRESS_LOGIN); } @Override public void onStart() { super.onStart(); startConnection(); } protected Dialog onCreateDialog(int id) { switch (id) { case DIALOG_PROGRESS_LOGIN: progressDialog = new ProgressDialog(Act_Main.this); progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); progressDialog.setMessage("Connecting.\nPlease wait..."); progressThreadLogin = new ProgressThreadLogin(); progressThreadLogin.start(); return progressDialog; case DIALOG_PROGRESS_NETWORK: [b]progressDialog = new ProgressDialog(Act_Main.this);[/b] progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); progressDialog.setMessage("Loading entire network.\nPlease wait..."); progressThreadNetwork = new ProgressThreadNetwork(); progressThreadNetwork.start(); return progressDialog; default: return null; } } // Define the Handler that receives messages from the thread and update the progress final Handler handler = new Handler() { public void handleMessage(Message msg) { int total = msg.getData().getInt("total"); int step = msg.getData().getInt("step"); Log.d(TAG, "handleMessage:PROCESSBAR:"+total); progressDialog.setProgress(total); if (total >= 100) { switch (step) { case UPDATE_NETWORK: dismissDialog(DIALOG_PROGRESS_LOGIN); showDialog(DIALOG_PROGRESS_NETWORK); cm.getNetwork(); break; .... default: break; } } } }; private class ProgressThreadLogin extends Thread { ProgressThreadLogin() { } public void run() { cm.login(); } } private class ProgressThreadNetwork extends Thread { ProgressThreadNetwork() { } public void run() { cm.getNetwork(); } } } And my connectionManager class: public class ConnectionManager { public ConnectionManager(Handler handler, DBAdapter db) { this.handler = handler; this.db = db; } public void updateProgressBar(int step, int value) { if (value == 0) total = total+1; else total = value ; Message msg = handler.obtainMessage(); Bundle b = new Bundle(); b.putInt("total", total); b.putInt("step", step); msg.setData(b); handler.handleMessage(msg); } public void login() { //DO MY LOGIN TASK updateProgressBar(Act_Main.UPDATE_NETWORK, 100); } } The crash errors occurs on the first line of "case DIALOG_PROGRESS_NETWORK:". My first progressbar is hidden but the second one is not displayed. I think I've done somthing wrong using the threads and handlers but I dont' know why. I was first using handler.sendMessage in place of handler.handleMessage but when I had several task in my connectionManager, the progressbar was updated only at the end of all tasks. Thank you in advance for your help

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  • Illegal cross thread operation exception, unable to handle it

    - by yeah1000
    Hello, i am using visual C# express 2008. I SOMETIMES get the illegal cross thread operation in my invoke method when i try to run my project. It use the same invoke method in many places but its only at the beginning of another thread that i get the error. I check the InvokeRequired property, invoke the same method and in the 'else' condition and create a temporary variable and assign it the text of my control. But on that line, in the 'else' statement, inside the Invoking method i sometimes get the exception. What could be the cause? How to get rid of it? It does not occur often, but it is still a bug... Code: // Delegate: private delegate void ChangeTextDelegate(string text); // Method: public static void ChangeText(string text) { if (richtextbox1.InvokeRequired) { richtextbox1.Invoke(new ChangeTextDelegate(ChangeText), new object[] { text }); } else { int startIndex; startIndex = richtextbox1.TextLength; // <- Exception points here. // ... } } Stack trace: System.InvalidOperationException was unhandled Message="Cross-thread operation not valid: Control 'SomeClass' accessed from a thread other than the thread it was created on." Source="System.Windows.Forms" StackTrace: at System.Windows.Forms.Control.get_Handle() at System.Windows.Forms.Control.get_InternalHandle() at System.Windows.Forms.Control.WmWindowPosChanged(Message& m) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.TextBoxBase.WndProc(Message& m) at System.Windows.Forms.RichTextBox.WndProc(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) at System.Windows.Forms.Control.DefWndProc(Message& m) at System.Windows.Forms.Control.WmCreate(Message& m) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.TextBoxBase.WndProc(Message& m) at System.Windows.Forms.RichTextBox.WndProc(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Forms.UnsafeNativeMethods.IntCreateWindowEx(Int32 dwExStyle, String lpszClassName, String lpszWindowName, Int32 style, Int32 x, Int32 y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu, HandleRef hInst, Object pvParam) at System.Windows.Forms.UnsafeNativeMethods.CreateWindowEx(Int32 dwExStyle, String lpszClassName, String lpszWindowName, Int32 style, Int32 x, Int32 y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu, HandleRef hInst, Object pvParam) at System.Windows.Forms.NativeWindow.CreateHandle(CreateParams cp) at System.Windows.Forms.Control.CreateHandle() at System.Windows.Forms.TextBoxBase.CreateHandle() at System.Windows.Forms.Control.get_Handle() at System.Windows.Forms.RichTextBox.get_TextLength() at SomeNamespace.SomeClass.Changetext(String text, Color color) in C:\...\SomeClass.cs:line 827 at SomeNamespace.SomeClass.SomeThreadFun() in C:\...\SomeClass.cs:line 112 at System.Threading.ThreadHelper.ThreadStart_Context(Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ThreadHelper.ThreadStart() InnerException: TY

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  • Boost.Thread Linking - boost_thread vs. boost_thread-mt

    - by Robert S. Barnes
    It's not clear to me what linking options exist for the Boost.Thread 1.34.1 library. I'm on Ubuntu 8.04 and I've found that using eitherr boost_thread or boost_thread-mt during linking both compile and run, but I don't see any documentation on these or any other linking options in above link. What Boost.Thread linking options are available and what do the mean?

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  • Help regarding C# thread pool

    - by Matt
    I have a method that gets called quite often, with text coming in as a parameter.. I'm looking at creating a thread pool that checks the line of text, and performs actions based on that.. Can someone help me out with the basics behind creating the thread pool and firing off new threads please? This is so damn confusing..

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  • can create a new thread on goog-app-engine ..(python)

    - by zjm1126
    i use this code can crteate ,but someone say it can't create ,why ? class LogText(db.Model): content = db.StringProperty(multiline=True) class MyThread(threading.Thread): def __init__(self,threadname): threading.Thread.__init__(self, name=threadname) def run(self,request): log=LogText() log.content=request.POST.get('content',None) log.put() def Log(request): thr = MyThread('haha') thr.run(request) return HttpResponse('')

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  • Twisted: why is it that passing a deferred callback to a deferred thread makes the thread blocking a

    - by surtyaarthoughts
    I unsuccessfully tried using txredis (the non blocking twisted api for redis) for a persisting message queue I'm trying to set up with a scrapy project I am working on. I found that although the client was not blocking, it became much slower than it could have been because what should have been one event in the reactor loop was split up into thousands of steps. So instead, I tried making use of redis-py (the regular blocking twisted api) and wrapping the call in a deferred thread. It works great, however I want to perform an inner deferred when I make a call to redis as I would like to set up connection pooling in attempts to speed things up further. Below is my interpretation of some sample code taken from the twisted docs for a deferred thread to illustrate my use case: #!/usr/bin/env python from twisted.internet import reactor,threads from twisted.internet.task import LoopingCall import time def main_loop(): print 'doing stuff in main loop.. do not block me!' def aBlockingRedisCall(): print 'doing lookup... this may take a while' time.sleep(10) return 'results from redis' def result(res): print res def main(): lc = LoopingCall(main_loop) lc.start(2) d = threads.deferToThread(aBlockingRedisCall) d.addCallback(result) reactor.run() if __name__=='__main__': main() And here is my alteration for connection pooling that makes the code in the deferred thread blocking : #!/usr/bin/env python from twisted.internet import reactor,defer from twisted.internet.task import LoopingCall import time def main_loop(): print 'doing stuff in main loop.. do not block me!' def aBlockingRedisCall(x): if x<5: #all connections are busy, try later print '%s is less than 5, get a redis client later' % x x+=1 d = defer.Deferred() d.addCallback(aBlockingRedisCall) reactor.callLater(1.0,d.callback,x) return d else: print 'got a redis client; doing lookup.. this may take a while' time.sleep(10) # this is now blocking.. any ideas? d = defer.Deferred() d.addCallback(gotFinalResult) d.callback(x) return d def gotFinalResult(x): return 'final result is %s' % x def result(res): print res def aBlockingMethod(): print 'going to sleep...' time.sleep(10) print 'woke up' def main(): lc = LoopingCall(main_loop) lc.start(2) d = defer.Deferred() d.addCallback(aBlockingRedisCall) d.addCallback(result) reactor.callInThread(d.callback, 1) reactor.run() if __name__=='__main__': main() So my question is, does anyone know why my alteration causes the deferred thread to be blocking and/or can anyone suggest a better solution?

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  • Android: raise AlertDialog from background thread

    - by Stefan Klumpp
    In my activity there's some stuff going on in a background thread, which gets started in Activity_1. The processing of the background thread takes a while and I want to notify the user when it's completed via an AlertDialog. However, the user might have changed to Activity_2 or Activity_3 in the meantime and I would like to pop up the AlertDialog always in the current Activity. Any idea how to realize this?

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  • Thread Management Object

    - by Gusdor
    I feel rather foolish as this is just a short question. I was reading about a bunch of thread management helper classes in .net, specifically one that aids the storage of threads to help a service manager object automatically invoke delegates onto the subscribing thread. I'm pretty sure it had something to do with creating dispatchers. Totally forgotten the name, can't find it :( Anyone know what I'm talking about?

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  • Django Thread-Safety for templatetags

    - by Acti67
    Hi, I am coming here, because I have a question about Django and Thread. I read the documentation http://docs.djangoproject.com/en/dev/howto/custom-template-tags/#template-tag-thread-safety and I would like to now if the next code could be impacted also, at the rendering context. class ChatterCountNode(NodeBase): def __init__(self, channelname, varname): self.channelname = channelname self.varname = varname def render(self, context): channelname = self.getvalue(context, self.channelname) varname = self.getvalue(context, self.varname) count = get_channel_count(channelname) context[varname] = count return '' Thank you for your time. Stéphane

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  • Thread affinity

    - by mita
    Can we set two thread or two task to execute with different processor affinity in C#.net Application? I have read about SetThreadAffinityMask but there is no example to have that used.. or Is there any way TPL(Task Parellel Libray) executes two thread/Task in with high priorty to use 100% cpu ?

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  • How to use timer in a thread

    - by Anjaneyulu
    Hi, I would like to send email notifications to users of my project exactly at 8 a.m, Here we are using a thread to send emails to the user. I would like to send some emails exactly at 8 A.M. How can I execute that perticular logic in this Thread. Please help me.

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  • Thread safety with heap-allocated memory

    - by incrediman
    I was reading this: http://en.wikipedia.org/wiki/Thread_safety Is the following function thread-safe? void foo(int y){ int * x = new int[50]; /*...do some stuff with the allocated memory...*/ delete x; } In the article it says that to be thread-safe you can only use variables from the stack. Really? Why? Wouldn't subsequent calls of the above function allocate memory elsewhere?

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  • final fields and thread-safety

    - by pcjuzer
    Should it be all fields, including super-fields, of a purposively immutable java class 'final' in order to be thread-safe or is it enough to have no modifier methods? Suppose I have a POJO with non-final fields where all fields are type of some immutable class. This POJO has getters-setters, and a constructor wich sets some initial value. If I extend this POJO with knocking out modifier methods, thus making it immutable, will extension class be thread-safe?

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  • Logging in worker threads spawned from a pylons application does not seem to work

    - by TimM
    I have a pylons application where, under certain cirumstances I want to spawn multiple worker threads to process items in a queue. Right now we aren't making use of a ThreadPool (would be ideal, but we'll add that in later). The main problem is that the worker threads logging does not get written to the log files. When I run the code outside of the pylons application the logging works fine. So I think its something to do with the pylons log handler but not sure what. Here is a basic example of the code (trimmed down): import logging log = logging.getLogger(__name__) import sys from Queue import Queue from threading import Thread, activeCount def run(input, worker, args = None, simulteneousWorkerLimit = None): queue = Queue() threads = [] if args is not None: if len(args) > 0: args = list(args) args = [worker, queue] + args args = tuple(args) else: args = (worker, queue) # start threads for i in range(4): t = Thread(target = __thread, args = args) t.daemon = True t.start() threads.append(t) # add ThreadTermSignal inputData = list(input) inputData.extend([ThreadTermSignal] * 4) # put in the queue for data in inputData: queue.put(data) # block until all contents are downloaded queue.join() log.critical("** A log line that appears fine **") del queue for thread in threads: del thread del threads class ThreadTermSignal(object): pass def __thread(worker, queue, *args): try: while True: data = queue.get() if data is ThreadTermSignal: sys.exit() try: log.critical("** I don't appear when run under pylons **") finally: queue.task_done() except SystemExit: queue.task_done() pass Take note, that the log lin within the RUN method will show up in the log files, but the log line within the worker method (which is run in a spawned thread), does not appear. Any help would be appreciated. Thanks ** EDIT: I should mention that I tried passing in the "log" variable to the worker thread as well as redefining a new "log" variable within the thread and neither worked. ** EDIT: Adding the configuration used for the pylons application (which comes out of the INI file). So the snippet below is from the INI file. [loggers] keys = root [handlers] keys = wsgierrors [formatters] keys = generic [logger_root] level = WARNING handlers = wsgierrors [handler_console] class = StreamHandler args = (sys.stderr,) level = WARNING formatter = generic [handler_wsgierrors] class = pylons.log.WSGIErrorsHandler args = () level = WARNING format = generic

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  • WebLogic stuck thread protection

    - by doublep
    By default WebLogic kills stuck threads after 15 min (600 s), this is controlled by StuckThreadMaxTime parameter. However, I cannot find more details on how exactly "stuckness" is defined. Specifically: What is the point at which 15 min countdown begins. Request processing start? Last wait()-like method? Something else? Does this apply only to request-processing threads or to all threads? I.e. can a request-processing thread "escape" this protection by spawning a worker thread for a long task? Especially, can it delegate response writing to such a worker without 15 min countdown? My usecase is download of huge files through a permission system. Since a user needs to be authenticated and have permissions to view a file, I cannot (or at least don't know how) leave this to a simple HTTP server, e.g. Apache. And because files can be huge, download could (at least in theory) take more than 15 minutes.

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