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  • Correct way to do timer function in Python

    - by bwawok
    Hi. I have a GUI application that needs to do something simple in the background (update a wx python progress bar, but that doesn't really matter). I see that there is a threading.timer class.. but there seems to be no way to make it repeat. So if I use the timer, I end up having to make a new thread on every single execution... like : import threading import time def DoTheDew(): print "I did it" t = threading.Timer(1, function=DoTheDew) t.daemon = True t.start() if __name__ == '__main__': t = threading.Timer(1, function=DoTheDew) t.daemon = True t.start() time.sleep(10) This seems like I am making a bunch of threads that do 1 silly thing and die.. why not write it as : import threading import time def DoTheDew(): while True: print "I did it" time.sleep(1) if __name__ == '__main__': t = threading.Thread(target=DoTheDew) t.daemon = True t.start() time.sleep(10) Am I missing some way to make a timer keep doing something? Either of these options seems silly... I am looking for a timer more like a java.util.Timer that can schedule the thread to happen every second... If there isn't a way in Python, which of my above methods is better and why?

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  • Java Concurrency in practice sample question

    - by andy boot
    I am reading "Java Concurrency in practice" and looking at the example code on page 51. This states that if a thread has references to a shared object then other threads may be able to access that object before the constructor has finished executing. I have tried to put this into practice and so I wrote this code thinking that if I ran it enough times a RuntimeException("World is f*cked") would occur. But it isn't doing. Is this a case of the Java spec not guaranting something but my particular implementation of java guaranteeing it for me? (java version: 1.5.0 on Ubuntu) Or have I misread something in the book? Code: (I expect an exception but it is never thrown) public class Threads { private Widgit w; public static void main(String[] s) throws Exception { while(true){ Threads t = new Threads(); t.runThreads(); } } private void runThreads() throws Exception{ new Checker().start(); w = new Widgit((int)(Math.random() * 100) + 1); } private class Checker extends Thread{ private static final int LOOP_TIMES = 1000; public void run() { int count = 0; for(int i = 0; i < LOOP_TIMES; i++){ try { w.checkMe(); count++; } catch(NullPointerException npe){ //ignore } } System.out.println("checked: "+count+" times out of "+LOOP_TIMES); } } private static class Widgit{ private int n; private int n2; Widgit(int n) throws InterruptedException{ this.n = n; Thread.sleep(2); this.n2 = n; } void checkMe(){ if (n != n2) { throw new RuntimeException("World is f*cked"); } } } }

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  • Class initialization and synchronized class method

    - by nybon
    Hi there, In my application, there is a class like below: public class Client { public synchronized static print() { System.out.println("hello"); } static { doSomething(); // which will take some time to complete } } This class will be used in a multi thread environment, many threads may call the Client.print() method simultaneously. I wonder if there is any chance that thread-1 triggers the class initialization, and before the class initialization complete, thread-2 enters into print method and print out the "hello" string? I see this behavior in a production system (64 bit JVM + Windows 2008R2), however, I cannot reproduce this behavior with a simple program in any environments. In Java language spec, section 12.4.1 (http://java.sun.com/docs/books/jls/second_edition/html/execution.doc.html), it says: A class or interface type T will be initialized immediately before the first occurrence of any one of the following: T is a class and an instance of T is created. T is a class and a static method declared by T is invoked. A static field declared by T is assigned. A static field declared by T is used and the reference to the field is not a compile-time constant (§15.28). References to compile-time constants must be resolved at compile time to a copy of the compile-time constant value, so uses of such a field never cause initialization. According to this paragraph, the class initialization will take place before the invocation of the static method, however, it is not clear if the class initialization need to be completed before the invocation of the static method. JVM should mandate the completion of class initialization before entering its static method according to my intuition, and some of my experiment supports my guess. However, I did see the opposite behavior in another environment. Can someone shed me some light on this? Any help is appreciated, thanks.

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  • UDP server doesnt accept calls from outside.

    - by rayman
    Hi, ive implement simple udp server on my Android device.(sdk 1.5) it works fine when i am runnning a local client on the phone sends through it trigger to my server. but when i try to get udp call from an outside server to my phone, it doesnt work. already make sure the outside server isnt blocked by firewall and it's sending the udp trigger to the right port, which my phone is listening to. i used natstat on the phone and checked that the phone is realy listening to the it's local ip and the port ive setted it to. here is my code of the server:(on the device) // server will listen to one client try { Thread udpServerThread = new Thread() { @Override public void run() { try { // Retrieve the ServerName InetAddress serverAddr = InetAddress .getByName("localhost"); Log.d("UDP", "S: Connecting..."); // Create new UDP-Socket socket = new DatagramSocket(SERVERPORT,serverAddr); byte[] buf = new byte[17]; // * Prepare a UDP-Packet that can contain the data we // * want to receive DatagramPacket packet = new DatagramPacket(buf, buf.length); Log.d("UDP", "S: Receiving..."); // wait to Receive the UDP-Packet socket.receive(packet); Log.d("UDP", "S: Received: '" + new String(packet.getData()) + "'"); acceptedMsg=new String(packet.getData()); notifyService(acceptedMsg); Log.d("UDP", "S: Done."); } catch (Exception e) { Log.e("UDP", "S: Error", e); } } }; udpServerThread.start(); } catch (Exception E) { Log.e("r",E.getMessage()) ; } so as i said, when i try it with local client(seperate thread) which sends udp trigger it works fine, but when i take this client implementation and put it on an outside real server, after UDP being sent, the phone doesnt respond to it. any idea? thanks, ray.

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  • C#, Can I check on a lock without trying to acquire it?

    - by Biff MaGriff
    Hello, I have a lock in my c# web app that prevents users from running the update script once it has started. I was thinking I would put a notification in my master page to let the user know that the data isn't all there yet. Currently I do my locking like so. protected void butRefreshData_Click(object sender, EventArgs e) { Thread t = new Thread(new ParameterizedThreadStart(UpdateDatabase)); t.Start(this); //sleep for a bit to ensure that javascript has a chance to get rendered Thread.Sleep(100); } public static void UpdateDatabase(object con) { if (Monitor.TryEnter(myLock)) { Updater.RepopulateDatabase(); Monitor.Exit(myLock); } else { Common.RegisterStartupScript(con, AlreadyLockedJavaScript); } } And I do not want to do if(Monitor.TryEnter(myLock)) Monitor.Exit(myLock); else //show processing labal As I imagine there is a slight possibility that it might display the notification when it isn't actually running. Is there an alternative I can use? Edit: Hi Everyone, thanks a lot for your suggestions! Unfortunately I couldn't quite get them to work... However I combined the ideas on 2 answers and came up with my own solution.

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  • Simple POSIX threads question

    - by Andy
    Hi, I have this POSIX thread: void subthread(void) { while(!quit_thread) { // do something ... // don't waste cpu cycles if(!quit_thread) usleep(500); } // free resources ... // tell main thread we're done quit_thread = FALSE; } Now I want to terminate subthread() from my main thread. I've tried the following: quit_thread = TRUE; // wait until subthread() has cleaned its resources while(quit_thread); But it does not work! The while() clause does never exit although my subthread clearly sets quit_thread to FALSE after having freed its resources! If I modify my shutdown code like this: quit_thread = TRUE; // wait until subthread() has cleaned its resources while(quit_thread) usleep(10); Then everything is working fine! Could someone explain to me why the first solution does not work and why the version with usleep(10) suddenly works? I know that this is not a pretty solution. I could use semaphores/signals for this but I'd like to learn something about multithreading, so I'd like to know why my first solution doesn't work. Thanks!

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  • UIImagePickerController crashes on rapid scrolling, slower than photos app

    - by vvanhee
    Most of the time, my image picker works perfectly (iOS 4.2.1). However, if I scroll very rapidly up and down about 4-6 times through my camera roll of about 300 photos, I get a crash. This never happens with the "photos" app on the same iPhone 3Gs. Also, I'm noticing that the stock "photos" app scrolls much more smoothly than my image picker. Has anyone else noticed this behavior? I'd be interested if others could attempt this in their own apps and see if they crash. I don't think it's related to other objects hogging memory on my iPhone because it's a simple app, and this happens right after I start the app. It also doesn't seem to be related to messages sent to other released objects or overreleasing of other objects in viewdidunload, based on my crash logs and the fact that the simulator responds well to simulated memory warnings. I think it might be a bug in the internal implementation of the UIImagePickerController... This is how I start the picker. I've done this multiple ways (including setting a retain property for the UIImagePickerController in my header and releasing on dealloc). This seems to be the best way (crashes least): UIImagePickerController *picker = [[UIImagePickerController alloc] init]; picker.delegate = self; picker.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum; picker.allowsEditing = YES; [self presentModalViewController:picker animated:YES]; [picker release]; This is the crashed thread (I get various exception types): Exception Type: SIGSEGV Exception Codes: SEGV_ACCERR at 0xfffffffff4faafa4 Crashed Thread: 8 ... Thread 8 Crashed: 0 CoreFoundation 0x000494ea -[__NSArrayM replaceObjectAtIndex:withObject:] + 98 1 PhotoLibrary 0x00008e0f -[PLImageTable _segmentAtIndex:] + 527 2 PhotoLibrary 0x00008a21 -[PLImageTable _mappedImageDataAtIndex:] + 221 3 PhotoLibrary 0x0000893f -[PLImageTable dataForEntryAtIndex:] + 15 4 PhotoLibrary 0x000087e7 PLThumbnailManagerImageDataAtIndex + 35 5 PhotoLibrary 0x00008413 -[PLThumbnailManager _dataForPhoto:format:width:height:bytesPerRow:dataWidth:dataHeight:imageDataOffset:imageDataFormat:preheat:] + 299 6 PhotoLibrary 0x000b6c13 __-[PLThumbnailManager preheatImageDataForImages:withFormat:]_block_invoke_1 + 159 7 libSystem.B.dylib 0x000d6680 _dispatch_call_block_and_release + 20 8 libSystem.B.dylib 0x000d6ba0 _dispatch_worker_thread2 + 128 9 libSystem.B.dylib 0x0007b251 _pthread_wqthread + 265

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  • Weird stuttering issues not related to GC.

    - by Smills
    I am getting some odd stuttering issues with my game even though my FPS never seems to drop below 30. About every 5 seconds my game stutters. I was originally getting stuttering every 1-2 seconds due to my garbage collection issues, but I have sorted those and will often go 15-20 seconds without a garbage collection. Despite this, my game still stutters periodically even when there is no GC listed in logcat anywhere near the stutter. Even when I take out most of my code and simply make my "physics" code the below code I get this weird slowdown issue. I feel that I am missing something or overlooking something. Shouldn't that "elapsed" code that I put in stop any variance in the speed of the main character related to changes in FPS? Any input/theories would be awesome. Physics: private void updatePhysics() { //get current time long now = System.currentTimeMillis(); //added this to see if I could speed it up, it made no difference Thread myThread = Thread.currentThread(); myThread.setPriority(Thread.MAX_PRIORITY); //work out elapsed time since last frame in seconds double elapsed = (now - mLastTime2) / 1000.0; mLastTime2 = now; //measures FPS and displays in logcat once every 30 frames fps+=1/elapsed; fpscount+=1; if (fpscount==30) { fps=fps/fpscount; Log.i("myActivity","FPS: "+fps+" Touch: "+touch); fpscount=0; } //this should make the main character (theoretically) move upwards at a steady pace mY-=100*elapsed; //increase amount I translate the draw to = main characters Y //location if the main character goes upwards if (mY<=viewY) { viewY=mY; } }

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  • Python : How to close a UDP socket while is waiting for data in recv ?

    - by alexroat
    Hello, let's consider this code in python: import socket import threading import sys import select class UDPServer: def __init__(self): self.s=None self.t=None def start(self,port=8888): if not self.s: self.s=socket.socket(socket.AF_INET, socket.SOCK_DGRAM) self.s.bind(("",port)) self.t=threading.Thread(target=self.run) self.t.start() def stop(self): if self.s: self.s.close() self.t.join() self.t=None def run(self): while True: try: #receive data data,addr=self.s.recvfrom(1024) self.onPacket(addr,data) except: break self.s=None def onPacket(self,addr,data): print addr,data us=UDPServer() while True: sys.stdout.write("UDP server> ") cmd=sys.stdin.readline() if cmd=="start\n": print "starting server..." us.start(8888) print "done" elif cmd=="stop\n": print "stopping server..." us.stop() print "done" elif cmd=="quit\n": print "Quitting ..." us.stop() break; print "bye bye" It runs an interactive shell with which I can start and stop an UDP server. The server is implemented through a class which launches a thread in which there's a infinite loop of recv/*onPacket* callback inside a try/except block which should detect the error and the exits from the loop. What I expect is that when I type "stop" on the shell the socket is closed and an exception is raised by the recvfrom function because of the invalidation of the file descriptor. Instead, it seems that recvfrom still to block the thread waiting for data even after the close call. Why this strange behavior ? I've always used this patter to implements an UDP server in C++ and JAVA and it always worked. I've tried also with a "select" passing a list with the socket to the xread argument, in order to get an event of file descriptor disruption from select instead that from recvfrom, but select seems to be "insensible" to the close too. I need to have a unique code which maintain the same behavior on Linux and Windows with python 2.5 - 2.6. Thanks.

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  • .NET TCP Client/Server communication issue

    - by Jamie
    What I'm currently trying to do is make a very basic webchat for irc using silverlight. Basically how I'm trying to do it is have a tcp server listening for connections from silverlight. When a client connects it creates a new connection to irc and data is passed to/from the client/irc via the server application. I've gotten it to work fine for one client connection, but as soon as two (or more) clients connect multiple connections are made to irc but all data passed from the clients just goes through the latest irc connection (if that makes sense). For example Client1, Client2 and Client3 are all connected to irc, but no matter who sends data it all comes through Client3. Between the client and server app it recognizes the data coming in from different clients so i believe the problems lies within the way I've connected to the irc. When the TCP server accepts a new client a new thread is made to listen to incoming data, and from there a new thread is made to connect to irc. I'm sure thats where the problem exists, but I've confused myself a lot now and am wondering if anyone can help me figure out a solution. EDIT: What I think is the problem, is that it can't distinguish which thread the specific client is using, so it just sends it via the latest one. Can this even be done?

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  • Java sockets: multiple client threads on same port on same machine?

    - by espcorrupt
    I am new to Socket programming in Java and was trying to understand if the below code is not a wrong thing to do. My question is: Can I have multiple clients on each thread trying to connect to a server instance in the same program and expect the server to read and write data with isolation between clients" public class Client extends Thread { ... void run() { Socket socket = new Socket("localhost", 1234); doIO(socket); } } public class Server extends Thread { ... void run() { // serverSocket on "localhost", 1234 Socket clientSock = serverSocket.accept(); executor.execute(new ClientWorker(clientSock)); } } Now can I have multiple Client instances on different threads trying to connect on the same port of the current machine? For example, Server s = new Server("localhost", 1234); s.start(); Client[] c = new Client[10]; for (int i = 0; i < c.length; ++i) { c.start(); }

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  • Load Testing Java Web Application - find TPS / Avg transaction response time

    - by Steve
    I would like to build my own load testing tool in Java with the goal of being able to load test a web application I am building throughout the development cycle. The web application will be receiving server to server HTTP Post requests and I would like to find its starting transaction per second (TPS) capacity along with the avgerage response time. The Post request and response messages will be in XML (I dont' think that's really applicable though :) ). I have written a very simple Java app to send transactions and count how many transactions it was able to send in one second (1000 ms) however I don't think this is the best way to load test. Really what I want is to send any number of transactions at exactly the same time - i.e. 10, 50, 100 etc. Any help would be appreciated! Oh and here is my current test app code: Thread[] t = new Thread[1]; for (int a = 0; a < t.length; a++) { t[a] = new Thread(new MessageLoop()); } startTime = System.currentTimeMillis(); System.out.println(startTime); for (int a = 0; a < t.length; a++) { t[a].start(); } while ((System.currentTimeMillis() - startTime) < 1000 ) { } if ((System.currentTimeMillis() - startTime) > 1000 ) { for (int a = 0; a < t.length; a++) { t[a].interrupt(); } } long endTime = System.currentTimeMillis(); System.out.println(endTime); System.out.println("Total time: " + (endTime - startTime)); System.out.println("Total transactions: " + count); private static class MessageLoop implements Runnable { public void run() { try { //Test Number of transactions while ((System.currentTimeMillis() - startTime) < 1000 ) { // SEND TRANSACTION HERE count++; } } catch (Exception e) { } } }

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  • threading in c#

    - by I__
    i am using this code: private void Form1_Load(object sender, EventArgs e) { } private void serialPort1_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e) { string response = serialPort1.ReadLine(); this.BeginInvoke(new MethodInvoker( () => textBox1.AppendText(response + "\r\n") )); } ThreadStart myThreadDelegate = new ThreadStart(ThreadWork.DoWork); Thread myThread = new Thread(myThreadDelegate); myThread.Start(); but am getting lots of errors: Error 2 The type or namespace name 'ThreadStart' could not be found (are you missing a using directive or an assembly reference?) C:\Users\alexluvsdanielle\AppData\Local\Temporary Projects\WindowsFormsApplication1\Form1.cs 31 44 WindowsFormsApplication1 Error 3 The name 'ThreadWork' does not exist in the current context C:\Users\alexluvsdanielle\AppData\Local\Temporary Projects\WindowsFormsApplication1\Form1.cs 31 56 WindowsFormsApplication1 Error 4 The type or namespace name 'Thread' could not be found (are you missing a using directive or an assembly reference?) C:\Users\alexluvsdanielle\AppData\Local\Temporary Projects\WindowsFormsApplication1\Form1.cs 32 31 WindowsFormsApplication1 Error 5 A field initializer cannot reference the non-static field, method, or property 'WindowsFormsApplication1.Form1.myThreadDelegate' C:\Users\alexluvsdanielle\AppData\Local\Temporary Projects\WindowsFormsApplication1\Form1.cs 32 38 WindowsFormsApplication1 what am i doing wrong?

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  • VB.NET Two different approaches to generic cross-threaded operations; which is better?

    - by BASnappl
    VB.NET 2010, .NET 4 Hello, I recently read about using SynchronizationContext objects to control the execution thread for some code. I have been using a generic subroutine to handle (possibly) cross-thread calls for things like updating UI controls that utilizes Invoke. I'm an amateur and have a hard time understanding the pros and cons of any particular approach. I am looking for some insight on which approach might be preferable and why. Update: This question is motivated, in part, by statements such as the following from the MSDN page on Control.InvokeRequired. An even better solution is to use the SynchronizationContext returned by SynchronizationContext rather than a control for cross-thread marshaling. Method 1: Public Sub InvokeControl(Of T As Control)(ByVal Control As T, ByVal Action As Action(Of T)) If Control.InvokeRequired Then Control.Invoke(New Action(Of T, Action(Of T))(AddressOf InvokeControl), New Object() {Control, Action}) Else Action(Control) End If End Sub Method 2: Public Sub UIAction(Of T As Control)(ByVal Control As T, ByVal Action As Action(Of Control)) SyncContext.Send(New Threading.SendOrPostCallback(Sub() Action(Control)), Nothing) End Sub Where SyncContext is a Threading.SynchronizationContext object defined in the constructor of my UI form: Public Sub New() InitializeComponent() SyncContext = WindowsFormsSynchronizationContext.Current End Sub Then, if I wanted to update a control (e.g., Label1) on the UI form, I would do: InvokeControl(Label1, Sub(x) x.Text = "hello") or UIAction(Label1, Sub(x) x.Text = "hello") So, what do y'all think? Is one way preferred or does it depend on the context? If you have the time, verbosity would be appreciated! Thanks in advance, Brian

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  • Java, Massive message processing with queue manager (trading)

    - by Ronny
    Hello, I would like to design a simple application (without j2ee and jms) that can process massive amount of messages (like in trading systems) I have created a service that can receive messages and place them in a queue to so that the system won't stuck when overloaded. Then I created a service (QueueService) that wraps the queue and has a pop method that pops out a message from the queue and if there is no messages returns null, this method is marked as "synchronized" for the next step. I have created a class that knows how process the message (MessageHandler) and another class that can "listen" for messages in a new thread (MessageListener). The thread has a "while(true)" and all the time tries to pop a message. If a message was returned, the thread calls the MessageHandler class and when it's done, he will ask for another message. Now, I have configured the application to open 10 MessageListener to allow multi message processing. I have now 10 threads that all time are in a loop. Is that a good design?? Can anyone reference me to some books or sites how to handle such scenario?? Thanks, Ronny

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  • Why does this threading approach not work?

    - by Tomas Lycken
    I have a wierd problem with threading in an ASP.NET application. For some reason, when I run the code in the request thread, everything works as expected. But when I run it in a separate thread, nothing happens. This is verified by calling the below handler with the three flags "on", "off" and "larma" respectively - in the two first cases everything works, but in the latter nothing happens. What am I doing wrong here? In the web project I have a generic handler with the following code: If task = "on" Then Alarm.StartaLarm(personId) context.Response.Write("Larmet är PÅ") ElseIf task = "off" Then Alarm.StoppaLarm(personId) context.Response.Write("Larmet är AV") ElseIf task = "larma" Then Alarm.Larma(personId) context.Response.Write("Larmar... (stängs av automagiskt)") Else context.Response.Write("inget hände - task: " & task) End If The Alarm class has the following methods: Private Shared Sub Larma_Thread(ByVal personId As Integer) StartaLarm(personId) Thread.Sleep(1000 * 30) StoppaLarm(personId) End Sub Public Shared Sub StartaLarm(ByVal personId As Integer) SandSMS(True, personId) End Sub Public Shared Sub StoppaLarm(ByVal personId As Integer) SandSMS(False, personId) End Sub Public Shared Sub SandSMS(ByVal setOn As Boolean, ByVal personId As Integer) ... End Sub

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  • Need help with threads in a client/server

    - by nunos
    For college, I am developing a local relay chat. I have to program a chat server and client that will only work on sending messages on different terminal windows on the same computer with threads and fifos. The fifos part I am having no trouble, the threads part is the one that is giving me some headaches. The server has one thread for receiving commands from a fifo (used by all clients) and another thread for each client that is connected. For each client that is connected I need to know a certain information. Firstly, I was using global variables, which worked as longs as there was only one client connected, which is much of a chat, to chat alone. So, ideally I would have some data like: -nickname -name -email -etc... per client that is connected. However, I don't know how to do that. I could create a client_data[MAX_NUMBER_OF_THREADS] where client_data was a struct with everything I needed to have access to, but this would require to, in every communication between server and client to ask for the id of the client in the array client_data and that does not seem very pratical I could also instantiate a client_data immediately after creating the thread but it would only be available in that block, and that is not very pratical either. As you can see I am in need of a little guidance here. Any comment, piece of code or link to any relevant information is greatly appreciated. Thanks.

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  • Calling NSFetchedResultsController & CoreData experts

    - by JK
    I am having a few nagging issues with NSFetchedResultsController and CoreData, any of which I would be very grateful to get help on. Issue 1 - Updates: I update my store on a background thread which results in certain rows being delete, inserted or updated. The changes are merged into the context on the main thread using the "mergeChangesFromContextDidSaveNotification:" method. Inserts and deletes are updated properly, but updates are not (e.g. the cell label is not updated with the change) although I have confirmed the updates to come through the contextDidSaveNotifcation, exactly like the inserts and deleted. My current workaround is to temporarily change the staleness interval of the context to 0, but this does not seem like the ideal solution. Issue 2 - Deleting objects: My fetch batch size is 20. If an object is deleted by the background thread which is in the first 20 rows, everything works fine. But if the object is after the first 20 rows and the table is scrolled down, a "CoreData could not fulfill a fault" error is raised. I have tried resaving the context and reperforming the frc fetch - all to no avail. Note: In this scenario, the frc delegate method "didChangeObject...." is not called for the delete - I assume this is because the object in question had not been faulted at that time (as it is was outside the initial fetch range). But for some reason, the context still thinks the object is around, although is has been deleted from the store. Issue 3 - Deleting sections : When the deletion of a row leads to the deletion of a section, I have gotten the "invalid number of rows in section???" error. I have worked around this by removing the "reloadSection" line from the NSFetchedResultsChangeMove: section and replacing it with "[tableView insertRowsAtIndexPaths...." This seems to work, but once again, I am not sure if this is the best solution. Any help would be greatly appreciated. Thank you!

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  • UIDocumentInteractionController & ARC: [UIPopoverController dealloc] reached while popover is still visible

    - by muffel
    This issue or similar issues have been discussed here before, but I didn't find any working solution for me. I am using the following code to display a UIDocumentInteractionController on an ARC-enabled iOS 7 project: - (void) exportDoc{ // [...] docController = [UIDocumentInteractionController interactionControllerWithURL:[NSURL fileURLWithPath:path]]; docController.delegate = self; [docController presentOpenInMenuFromBarButtonItem:mainMenuButton animated:YES]; } First I didn't want to create a property that holds the controller reference, but as many people said that there are not alternatives to it. It is defined as @property (strong) UIDocumentInteractionController* docController; exportDoc is run in the main thread using NSOperationQueue. Whenever it is executed, I get the following error message: Terminating app due to uncaught exception 'NSGenericException', reason: '-[UIPopoverController dealloc] reached while popover is still visible.' This is what the backtrace says: (lldb) bt * thread #1: tid = 0x1c97d9, 0x000000019a23c1c0 libobjc.A.dylibobjc_exception_throw, queue = 'com.apple.main-thread', stop reason = breakpoint 2.1 frame #0: 0x000000019a23c1c0 libobjc.A.dylibobjc_exception_throw frame #1: 0x000000018d982e90 CoreFoundation+[NSException raise:format:] + 128 frame #2: 0x0000000190bc348c UIKit-[UIPopoverController dealloc] + 96 frame #3: 0x0000000190e18fc8 UIKit-[UIDocumentInteractionController dealloc] + 168 frame #4: 0x000000019a255474 libobjc.A.dylib(anonymous namespace)::AutoreleasePoolPage::pop(void*) + 524 frame #5: 0x000000018d881988 CoreFoundation_CFAutoreleasePoolPop + 28 frame #6: 0x000000018e42cb18 Foundation-[NSOperationInternal _start:] + 892 frame #7: 0x000000018e4eea38 Foundation__NSOQSchedule_f + 76 frame #8: 0x000000019a813fd4 libdispatch.dylib_dispatch_client_callout + 16 frame #9: 0x000000019a8171dc libdispatch.dylib_dispatch_main_queue_callback_4CF + 336 frame #10: 0x000000018d942c2c CoreFoundation__CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE + 12 frame #11: 0x000000018d940f6c CoreFoundation__CFRunLoopRun + 1452 frame #12: 0x000000018d881c20 CoreFoundationCFRunLoopRunSpecific + 452 frame #13: 0x0000000193511c0c GraphicsServicesGSEventRunModal + 168 frame #14: 0x00000001909b2fdc UIKitUIApplicationMain + 1156 * frame #15: 0x000000010000947c MyApplicationmain(argc=1, argv=0x000000016fdfbc80) + 108 at main.m:16 frame #16: 0x000000019a82faa0 libdyld.dylibstart + 4 As far as I understand the autoreleasepool just releases the controller. Shouldn't this be prevented by using a strong property just as I did? Do you have any idea what the problem can be and how I can solve it?

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  • What is the simplest way to implement multithreading in c# to existing code

    - by Kaeso
    I have already implemented a functionnal application that parses 26 pages of html all at once to produce an xml file with data contained on the web pages. I would need to implement a thread so that this method can work in the background without causing my app to seems unresponsive. Secondly, I have another function that is decoupled from the first one which compares two xml files to produce a third one and then transform this third xml file to produce an html page using XSLT. This would have to be on a thread, where I can click Cancel to stop the thread whithout crashing the app. What is the easiest best way to do this using WPF forms in VS 2010 ? I have chosen to use the BackgroundWorker. BackgroundWorker implementation: public partial class MainWindow : Window { private BackgroundWorker bw = new BackgroundWorker(); public MainWindow() { InitializeComponent(); bw.WorkerReportsProgress = true; bw.DoWork += new DoWorkEventHandler(bw_DoWork); bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted); } private void Window_Loaded(object sender, RoutedEventArgs e) { this.LoadFiles(); } private void btnCompare_Click(object sender, EventArgs e) { if (bw.IsBusy != true) { progressBar2.IsIndeterminate = true; // Start the asynchronous operation. bw.RunWorkerAsync(); } } private void bw_DoWork(object sender, DoWorkEventArgs e) { StatsProcessor proc = new StatsProcessor(); if (lstStatsBox1.SelectedItem != null) if (lstStatsBox2.SelectedItem != null) proc.CompareStats(lstStatsBox1.SelectedItem.ToString(), lstStatsBox2.SelectedItem.ToString()); } private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { progressBar2.IsIndeterminate = false; progressBar2.Value = 100; } I have started with the bgworker solution, but it seems that the bw_DoWork method is never called when btnCompare is clicked, I must be doing something wrong... I am new to threads.

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  • Repeated host lookups failing in urllib2

    - by reve_etrange
    I have code which issues many HTTP GET requests using Python's urllib2, in several threads, writing the responses into files (one per thread). During execution, it looks like many of the host lookups fail (causing a name or service unknown error, see appended error log for an example). Is this due to a flaky DNS service? Is it bad practice to rely on DNS caching, if the host name isn't changing? I.e. should a single lookup's result be passed into the urlopen? Exception in thread Thread-16: Traceback (most recent call last): File "/usr/lib/python2.6/threading.py", line 532, in __bootstrap_inner self.run() File "/home/da/local/bin/ThreadedDownloader.py", line 61, in run page = urllib2.urlopen(url) # get the page File "/usr/lib/python2.6/urllib2.py", line 126, in urlopen return _opener.open(url, data, timeout) File "/usr/lib/python2.6/urllib2.py", line 391, in open response = self._open(req, data) File "/usr/lib/python2.6/urllib2.py", line 409, in _open '_open', req) File "/usr/lib/python2.6/urllib2.py", line 369, in _call_chain result = func(*args) File "/usr/lib/python2.6/urllib2.py", line 1170, in http_open return self.do_open(httplib.HTTPConnection, req) File "/usr/lib/python2.6/urllib2.py", line 1145, in do_open raise URLError(err) URLError: <urlopen error [Errno -2] Name or service not known>

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  • Why is CoRegisterClassObject creating two extra threads?

    - by Stijn Sanders
    I'm trying to fix a problem that only recently happens on a number of machine's on a VPN. They each run a client application I wrote that exposes a COM automation object. For some strange reason I haven't been able to discover yet, one thread in the application takes up all of the available CPU time, slowing other operation on the machine. In observing the application's strange behaviour, I've noticed it's the third thread started, and if I debug on my machine I notice the first call to CoRegisterClassObject created two extra threads. If the second of these two threads is the one that gets into an infinite loop, I'm not at all shure how to fix this. Where could I check next about what's wrong? Could it have started by one of the recent patches rolled out by Microsoft this last 'patch tuesday'? I had a go with ProcessExplorer to extract a stack trace of the thread: ntoskrnl.exe!ExReleaseResourceLite+0x1a3 ntoskrnl.exe!PsGetContextThread+0x329 WLDAP32.dll!Ordinal325+0x1231 WLDAP32.dll!Ordinal325+0x129e WLDAP32.dll!Ordinal325+0x1178 ntdll.dll!LdrInitializeThunk+0x24 ntdll.dll!LdrShutdownThread+0xe9 kernel32.dll!ExitThread+0x3e kernel32.dll!FreeLibraryAndExitThread+0x1e ole32.dll!StringFromGUID2+0x65d kernel32.dll!GetModuleFileNameA+0x1ba

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  • Android Bluetooth syncing

    - by Darryl
    I am connecting to a bluetooth enabled camera, and I am able to connect using the methods found in the BluetoothChat example. I need to send commands to the camera. The issue is that I also need to get a response BACK from the camera after I send the command in the first place. So basically I need to write a command and receive a response. However, the thing is that the commands sometimes don't generate a response. Even the documentation on the camera says that you "have to send the sync command as many as 25 times on power up before you will get a response." So I cannot just write a command and wait for a response, as the "read" function blocks the thread. If I have the read function in another thread, like the bluetooth chat example, there seems to be sync issues, i.e., if I issue a write command, how can I know that it is reading if that is happening in another thread? I did set a global variable to check for, but this seems "iffy" at best. So basically I need to write to the bluetooth and then attempt to read from it. However, I need to let that read timeout and if I haven't received a response, I need to write again until I get a response (or until it's tried a set number of times). I don't need the read function to be going all the time in the background. Any ideas? Thanks in advance for your time.

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  • Why is only the first shown window focusable

    - by Miha Markic
    Imagine the code below. Only the first window appears on the top, all of subsequent windows won't nor can they be programatically focused for some reason (they appear in the background). Any idea how to workaround this? BTW, static methods/properties are not allowed nor is any global property. [STAThread] static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); Thread t1 = new Thread(CreateForm); t1.SetApartmentState(ApartmentState.STA); t1.Start(); t1.Join(); t1 = new Thread(CreateForm); t1.SetApartmentState(ApartmentState.STA); t1.Start(); t1.Join(); } private static void CreateForm() { using (Form f = new Form()) { System.Windows.Forms.Timer t = new System.Windows.Forms.Timer { Enabled = true, Interval = 2000 }; t.Tick += (s, e) => { f.Close(); t.Enabled = false; }; f.TopMost = true; Application.Run(f); } }

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  • pthread_create followed by pthread_detach still results in possibly lost error in Valgrind.

    - by alesplin
    I'm having a problem with Valgrind telling me I have some memory possible lost: ==23205== 544 bytes in 2 blocks are possibly lost in loss record 156 of 265 ==23205== at 0x6022879: calloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) ==23205== by 0x540E209: allocate_dtv (in /lib/ld-2.12.1.so) ==23205== by 0x540E91D: _dl_allocate_tls (in /lib/ld-2.12.1.so) ==23205== by 0x623068D: pthread_create@@GLIBC_2.2.5 (in /lib/libpthread-2.12.1.so) ==23205== by 0x758D66: MTPCreateThreadPool (MTP.c:290) ==23205== by 0x405787: main (MServer.c:317) The code that creates these threads (MTPCreateThreadPool) basically gets an index into a block of waiting pthread_t slots, and creates a thread with that. TI becomes a pointer to a struct that has a thread index and a pthread_t. (simplified/sanitized): for (tindex = 0; tindex < NumThreads; tindex++) { int rc; TI = &TP->ThreadInfo[tindex]; TI->ThreadID = tindex; rc = pthread_create(&TI->ThreadHandle,NULL,MTPHandleRequestsLoop,TI); /* check for non-success that I've omitted */ pthread_detach(&TI->ThreadHandle); } Then we have a function MTPDestroyThreadPool that loops through all the threads we created and cancels them (since the MTPHandleRequestsLoop doesn't exit). for (tindex = 0; tindex < NumThreads; tindex++) { pthread_cancel(TP->ThreadInfo[tindex].ThreadHandle); } I've read elsewhere (including other questions here on SO) that detaching a thread explicitly would prevent this possibly lost error, but it clearly isn't. Any thoughts?

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