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• WPF Dispatcher.BeginInvoke crash on Windows XP

  - by amr-ne

  Hi, I have a WPF application and a worker thread. The worker thread invokes a callback on the UI thread, which opens a new dialog. Works fine on Win7, but on XP it will crash. In worker thread: someWpfDialogInstance.Dispatcher.BeginInvoke(openSomeDialogCallback, null); Does someone knows a solution or a workaround for this problem?

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• C++ to bytecode compiler for Silverlight CLR?

  - by paleozogt

  I'd like to be able to compile a C/C++ library so that it runs within a safe managed runtime in the Silverlight CLR. There are several tools for doing this with the JVM that allows C++ code to run within a CRT emulation layer (see NestedVM, LLJVM, etc), which effectively allows C++ code to be run within a Java Applet. There's even a tool for this for the Adobe Flash VM (see Alchemy). However, I can't seem to find any tools like this for the CLR. fyi, the MSVC tools don't seem to allow for this: The /clr:pure flag will create C++ code that runs in the CLR, but it isn't safe (because the CRT isn't safe) and /clr:safe requires massive code changes (no native types, etc).

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• junit annotation

  - by lamisse

  I wish to launch the GUI appli 2 times from java test how should we use @annotation in this case? example : @BeforeClass public static void setupOnce() { final Thread thread = new Thread() { public void run() { //launche appli } }; try { thread.start(); when I call this function from test @test public void test(){ setuponce(); } to launch it a second time which annotation should I use? @afterclass? thanks

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• .NET threading question

  - by MusiGenesis

  Is there any essential difference between this code: ThreadStart starter = new ThreadStart(SomeMethod); starter.Invoke(); and this? ThreadStart starter = new ThreadStart(SomeMethod); Thread th = new Thread(starter); th.Start(); Or does the first invoke the method on the current thread while the second invokes it on a new thread?

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• iPhone App is leaking memory; Instruments and Clang cannot find the leak

  - by Norbert

  Hi, i've developed an iPhone program which is kind of an image manipulation program: The user get an UIImagePickerController and selects an image. Then the program does some heavy calculating in a new thread (for responsiveness of the application). The thread has, of course, its own autorelease pool. When calculation is done, the seperated thread signals the main thread that the result can be presented. The app creates a new view controller, pushes it onto the navigation controller. In short: UIImagePickerController new thread (autorelease pool) does some heavy calculation with image data signal to main thread that it's done main thread creates view controller and pushes it onto navigation controller view controller presents image result My program works well, but if I dismiss the navigation controller's top view controller by tapping on the back button and repeat the whole process several times, my app crashes. But only on the device! Instruments cannot find any leaks (except for some minor ones which I don't feel responsible for: thread creation, NSCFString; overall about 10 kB). Even Clang static analyzer tells me that my could seems to be all right. I know that the UIImage class can cache images and objects returned from convenience methods get freed only whet their autorelease pool gets drained. But most of the time I work with CGImageRef and I use UIImage' alloc, init & release methods to free memory as soon as possible. Currently, I don't know how to isolate the problem. How would you approach this problem? Crash Log: Incident Identifier: F4C202C9-1338-48FC-80AD-46248E6C7154 CrashReporter Key: bb6f526d8b9bb680f25ea8e93bb071566ccf1776 OS Version: iPhone OS 3.1.1 (7C145) Date: 2009-09-26 14:18:57 +0200 Free pages: 372 Wired pages: 7754 Purgeable pages: 0 Largest process: _MY_APP_ Processes Name UUID Count resident pages _MY_APP_ <032690e5a9b396058418d183480a9ab3> 17766 (jettisoned) (active) debugserver <ec29691560aa0e2994f82f822181bffd> 107 syslog_relay <21e13fa2b777218bdb93982e23fb65d3> 62 notification_pro <8a7725017106a28b545fd13ed58bf98c> 64 notification_pro <8a7725017106a28b545fd13ed58bf98c> 64 afcd <98b45027fbb1350977bf1ca313dee527> 65 mediaserverd <eb8fe997a752407bea573cd3adf568d3> 319 ptpd <b17af9cf6c4ad16a557d6377378e8a1e> 142 syslogd <ec8a5bc4483638539fa1266363dee8b8> 68 BTServer <1bb74831f93b1d07c48fb46cc31c15da> 119 apsd <a639ba83e666cc1d539223923ce59581> 165 notifyd <2ed3a1166da84d8d8868e64d549cae9d> 101 CommCenter <f4239480a623fb1c35fa6c725f75b166> 161 SpringBoard <8919df8091fdfab94d9ae05f513c0ce5> 2681 (active) accessoryd <b66bcf6e77c3ee740c6a017f54226200> 90 configd <41e9d763e71dc0eda19b0afec1daee1d> 275 fairplayd <cdce5393153c3d69d23c05de1d492bd4> 108 mDNSResponder <f3ef7a6b24d4f203ed147f476385ec53> 103 lockdownd <6543492543ad16ff0707a46e512944ff> 297 launchd <73ce695fee09fc37dd70b1378af1c818> 71 **End**

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• Threading questions

  - by JK

  If I spawn a secondary thread and the threaded method calls other methods, are those methods run in the secondary thread or the main thread? Is there a way to determine on which thread a specified piece of code is being run?

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• How to do the processing and keep GUI refreshed using databinding?

  - by macias

  History of the problem This is continuation of my previous question How to start a thread to keep GUI refreshed? but since Jon shed new light on the problem, I would have to completely rewrite original question, which would make that topic unreadable. So, new, very specific question. The problem Two pieces: CPU hungry heavy-weight processing as a library (back-end) WPF GUI with databinding which serves as monitor for the processing (front-end) Current situation -- library sends so many notifications about data changes that despite it works within its own thread it completely jams WPF data binding mechanism, and in result not only monitoring the data does not work (it is not refreshed) but entire GUI is frozen while processing the data. The aim -- well-designed, polished way to keep GUI up to date -- I am not saying it should display the data immediately (it can skip some changes even), but it cannot freeze while doing computation. Example This is simplified example, but it shows the problem. XAML part: <StackPanel Orientation="Vertical"> <Button Click="Button_Click">Start</Button> <TextBlock Text="{Binding Path=Counter}"/> </StackPanel> C# part (please NOTE this is one piece code, but there are two sections of it): public partial class MainWindow : Window,INotifyPropertyChanged { // GUI part public MainWindow() { InitializeComponent(); DataContext = this; } private void Button_Click(object sender, RoutedEventArgs e) { var thread = new Thread(doProcessing); thread.IsBackground = true; thread.Start(); } // this is non-GUI part -- do not mess with GUI here public event PropertyChangedEventHandler PropertyChanged; public void OnPropertyChanged(string property_name) { if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs(property_name)); } long counter; public long Counter { get { return counter; } set { if (counter != value) { counter = value; OnPropertyChanged("Counter"); } } } void doProcessing() { var tmp = 10000.0; for (Counter = 0; Counter < 10000000; ++Counter) { if (Counter % 2 == 0) tmp = Math.Sqrt(tmp); else tmp = Math.Pow(tmp, 2.0); } } } Known workarounds (Please do not repost them as answers) Those two first are based on Jon ideas: pass GUI dispatcher to library and use it for sending notifications -- why it is ugly? because it could be no GUI at all give up with data binding COMPLETELY (one widget with databinding is enough for jamming), and instead check from time to time data and update the GUI manually -- well, I didn't learn WPF just to give up with it now ;-) and this is mine, it is ugly, but simplicity of it kills -- before sending notification freeze a thread -- Thread.Sleep(1) -- to let the potential receiver "breathe" -- it works, it is minimalistic, it is ugly though, and it ALWAYS slows down computation even if no GUI is there So... I am all ears for real solutions, not some tricks.

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• How to interpret Objective-C errors?

  - by Greg Maletic

  I'm getting the following error: 2010-05-11 17:46:28.475 MyApp[54112:5e1b] bool _WebTryThreadLock(bool), 0x140faa0: Tried to obtain the web lock from a thread other than the main thread or the web thread. This may be a result of calling to UIKit from a secondary thread. Crashing now... Is there any way for me to figure out where [54112:5e1b] is in my code, so I can try to narrow down the error? Thanks.

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• Problem while adding a new value to a hashtable when it is enumerated

  - by karthik

  `hi I am doing a simple synchronous socket programming,in which i employed twothreads one for accepting the client and put the socket object into a collection,other thread will loop through the collection and send message to each client through the socket object. the problem is 1.i connect to clients to the server and start send messages 2.now i want to connect a new client,while doing this i cant update the collection and add a new client to my hashtable.it raises an exception "collection modified .Enumeration operation may not execute" how to add a NEW value without having problems in a hashtable. private void Listen() { try { //lblStatus.Text = "Server Started Listening"; while (true) { Socket ReceiveSock = ServerSock.Accept(); //keys.Clear(); ConnectedClients = new ListViewItem(); ConnectedClients.Text = ReceiveSock.RemoteEndPoint.ToString(); ConnectedClients.SubItems.Add("Connected"); ConnectedList.Items.Add(ConnectedClients); ClientTable.Add(ReceiveSock.RemoteEndPoint.ToString(), ReceiveSock); //foreach (System.Collections.DictionaryEntry de in ClientTable) //{ // keys.Add(de.Key.ToString()); //} //ClientTab.Add( //keys.Add( } //lblStatus.Text = "Client Connected Successfully."; } catch (Exception ex) { MessageBox.Show(ex.Message); } } private void btn_receive_Click(object sender, EventArgs e) { Thread receiveThread = new Thread(new ThreadStart(Receive)); receiveThread.IsBackground = true; receiveThread.Start(); } private void Receive() { while (true) { //lblMsg.Text = ""; byte[] Byt = new byte[2048]; //ReceiveSock.Receive(Byt); lblMsg.Text = Encoding.ASCII.GetString(Byt); } } private void btn_Send_Click(object sender, EventArgs e) { Thread SendThread = new Thread(new ThreadStart(SendMsg)); SendThread.IsBackground = true; SendThread.Start(); } private void btnlist_Click(object sender, EventArgs e) { //Thread ListThread = new Thread(new ThreadStart(Configure)); //ListThread.IsBackground = true; //ListThread.Start(); } private void SendMsg() { while (true) { try { foreach (object SockObj in ClientTable.Keys) { byte[] Tosend = new byte[2048]; Socket s = (Socket)ClientTable[SockObj]; Tosend = Encoding.ASCII.GetBytes("FirstValue&" + GenerateRandom.Next(6, 10).ToString()); s.Send(Tosend); //ReceiveSock.Send(Tosend); Thread.Sleep(300); } } catch (Exception ex) { MessageBox.Show(ex.Message); } } }

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• Does add() on LinkedBlockingQueue notify waiting threads?

  - by obvio171

  I have a consumer thread taking elements from a LinkedBlockingQueue, and I make it sleep manually when it's empty. I use peek() to see if the queue empty because I have to do stuff because sending the thread to sleep, and I do that with queue.wait(). So, when I'm in another thread and add()an element to the queue, does that automatically notify the thread that was wait()ing on the queue?

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• java double buffering problem

  - by russell

  Whats wrong with my applet code which does not render double buffering correctly.I am trying and trying.But failed to get a solution.Plz Plz someone tell me whats wrong with my code. import java.applet.* ; import java.awt.* ; import java.awt.event.* ; public class Ball extends Applet implements Runnable { // Initialisierung der Variablen int x_pos = 10; // x - Position des Balles int y_pos = 100; // y - Position des Balles int radius = 20; // Radius des Balles Image buffer=null; //Graphics graphic=null; int w,h; public void init() { Dimension d=getSize(); w=d.width; h=d.height; buffer=createImage(w,h); //graphic=buffer.getGraphics(); setBackground (Color.black); } public void start () { // Schaffen eines neuen Threads, in dem das Spiel l?uft Thread th = new Thread (this); // Starten des Threads th.start (); } public void stop() { } public void destroy() { } public void run () { // Erniedrigen der ThreadPriority um zeichnen zu erleichtern Thread.currentThread().setPriority(Thread.MIN_PRIORITY); // Solange true ist l?uft der Thread weiter while (true) { // Ver?ndern der x- Koordinate repaint(); x_pos++; y_pos++; //x2--; //y2--; // Neuzeichnen des Applets if(x_pos>410) x_pos=20; if(y_pos>410) y_pos=20; try { Thread.sleep (30); } catch (InterruptedException ex) { // do nothing } Thread.currentThread().setPriority(Thread.MAX_PRIORITY); } } public void paint (Graphics g) { Graphics screen=null; screen=g; g=buffer.getGraphics(); g.setColor(Color.red); g.fillOval(x_pos - radius, y_pos - radius, 2 * radius, 2 * radius); g.setColor(Color.green); screen.drawImage(buffer,0,0,this); } public void update(Graphics g) { paint(g); } } what change should i make.When offscreen image is drawn the previous image also remain in screen.How to erase the previous image from the screen??

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• WinForm-style Invoke() in unmanaged C++

  - by Matt Green

  I've been playing with a DataBus-type design for a hobby project, and I ran into an issue. Back-end components need to notify the UI that something has happened. My implementation of the bus delivers the messages synchronously with respect to the sender. In other words, when you call Send(), the method blocks until all the handlers have called. (This allows callers to use stack memory management for event objects.) However, consider the case where an event handler updates the GUI in response to an event. If the handler is called, and the message sender lives on another thread, then the handler cannot update the GUI due to Win32's GUI elements having thread affinity. More dynamic platforms such as .NET allow you to handle this by calling a special Invoke() method to move the method call (and the arguments) to the UI thread. I'm guessing they use the .NET parking window or the like for these sorts of things. A morbid curiosity was born: can we do this in C++, even if we limit the scope of the problem? Can we make it nicer than existing solutions? I know Qt does something similar with the moveToThread() function. By nicer, I'll mention that I'm specifically trying to avoid code of the following form: if(! this->IsUIThread()) { Invoke(MainWindowPresenter::OnTracksAdded, e); return; } being at the top of every UI method. This dance was common in WinForms when dealing with this issue. I think this sort of concern should be isolated from the domain-specific code and a wrapper object made to deal with it. My implementation consists of: DeferredFunction - functor that stores the target method in a FastDelegate, and deep copies the single event argument. This is the object that is sent across thread boundaries. UIEventHandler - responsible for dispatching a single event from the bus. When the Execute() method is called, it checks the thread ID. If it does not match the UI thread ID (set at construction time), a DeferredFunction is allocated on the heap with the instance, method, and event argument. A pointer to it is sent to the UI thread via PostThreadMessage(). Finally, a hook function for the thread's message pump is used to call the DeferredFunction and de-allocate it. Alternatively, I can use a message loop filter, since my UI framework (WTL) supports them. Ultimately, is this a good idea? The whole message hooking thing makes me leery. The intent is certainly noble, but are there are any pitfalls I should know about? Or is there an easier way to do this?

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• What problems might arise when sharing an int between two threads?

  - by Tobbe

  Two threads accesses a shared int, x. What problems can arise from instruction reordering etc. Thread 1: x = 1; Thread 2: obj.f(x); What would change if x is declarared volatile? What would change if Thread 1 and Thread 2 runs on different cores?

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• Ruby: Alter class static method in a code block

  - by Phuong Nguy?n

  Given the Thread class with it current method. Now inside a test, I want to do this: def test_alter_current_thread Thread.current = a_stubbed_method # do something that involve the work of Thread.current Thread.current = default_thread_current end Basically, I want to alter the method of a class inside a test method and recover it after that. I know it sound complex for another language, like Java & C# (in Java, only powerful mock framework can do it). But it's ruby and I hope such nasty stuff would be available

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• What are common uses of condition variables in C++?

  - by jasonline

  I'm trying to learn about condition variables. I would like to know what are the common situations where condition variables are used. One example is in a blocking queue, where two threads access the queue - the producer thread pushes an item into the queue, while the consumer thread pops an item from the queue. If the queue is empty, the consumer thread is waiting until a signal is sent by the producer thread. What are other design situations where you need a condition variable to be used?

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• Python cannot go over internet network

  - by user1642826

  I am currently trying to work with python networking and I have reached a bit of a road block. I am not able to network with any computer but localhost, which is kind-of useless with what networking is concerned. I have tried on my local network, from one computer to another, and I have tried over the internet, both fail. The only time I can make it work is if (when running on the server's computer) it's ip is set as 'localhost' or '192.168.2.129' (computers ip). I have spent hours going over opening ports with my isp and have gotten nowhere, so I decided to try this forum. I have my windows firewall down and I have included some pictures of important screen shots. I have no idea what the problem is and this has spanned almost a year of calls to my isp. The computer, modem, and router have all been replaced in that time. Screen shots: import socket import threading import socketserver class ThreadedTCPRequestHandler(socketserver.BaseRequestHandler): def handle(self): data = self.request.recv(1024) cur_thread = threading.current_thread() response = "{}: {}".format(cur_thread.name, data) self.request.sendall(b'worked') class ThreadedTCPServer(socketserver.ThreadingMixIn, socketserver.TCPServer): pass def client(ip, port, message): sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.connect((ip, port)) try: sock.sendall(message) response = sock.recv(1024) print("Received: {}".format(response)) finally: sock.close() if __name__ == "__main__": # Port 0 means to select an arbitrary unused port HOST, PORT = "192.168.2.129", 9000 server = ThreadedTCPServer((HOST, PORT), ThreadedTCPRequestHandler) ip, port = server.server_address # Start a thread with the server -- that thread will then start one # more thread for each request server_thread = threading.Thread(target=server.serve_forever) # Exit the server thread when the main thread terminates server_thread.daemon = True server_thread.start() print("Server loop running in thread:", server_thread.name) ip = '12.34.56.789' print(ip, port) client(ip, port, b'Hello World 1') client(ip, port, b'Hello World 2') client(ip, port, b'Hello World 3') server.shutdown() I do not know where the error is occurring. I get this error: Traceback (most recent call last): File "C:\Users\Dr.Frev\Desktop\serverTest.py", line 43, in <module> client(ip, port, b'Hello World 1') File "C:\Users\Dr.Frev\Desktop\serverTest.py", line 18, in client sock.connect((ip, port)) socket.error: [Errno 10061] No connection could be made because the target machine actively refused it Any help will be greatly appreciated. *if this isn't a proper forum for this, could someone direct me to a more appropriate one.

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• DTOs Collections mapping Problem

  - by the_knight5000

  I'm working now on a multi-tier project which has layers as following : DAL BLL GUI Layer and Shared DTOs between BLL and GUI layers. I'm facing a problem in mapping the Objects from DAO To DTO, No problem in the simple objects. The problem is in the Objects who have child collections of another objects. ex: Author Category --Categories --Authors the execution goes in an infinite loop of mapping and it get more complex when I want model Self-join tables ex: Safe Safe --TransferSafe(Collection<Safe>) --TransferSafe(Collection<Safe>) the execution goes in an infinite loop of mapping any suggestions about a good solution or a practical mapping pattern?

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• Waiting for a subset of threads in a Java ThreadPool

  - by David Semeria

  Let's say I have a thread pool containing X items, and a given task employs Y of these items (where Y is much smaller than X). I want to wait for all of the threads of a given task (Y items) to finish, not the entire thread pool. If the thread pool's execute() method returned a reference to the employed thread I could simply join() to each of these Y threads, but it doesn't. Does anyone know of an elegant way to accomplish this? Thanks.

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• Ruby multiple background threads

  - by turri

  I need to run multiple background threads in a thread pool with timeout. The scheme is something like: #!/usr/bin/env ruby require 'thread' def foo(&block) bar(block) end def bar(block) Thread.abort_on_exception=true @main = Thread.new { block.call } end foo { sleep 1 puts 'test' } Why if i run that i get no output? (and no sleep wait?)

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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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• What Apache/PHP configurations do you know and how good are they?

  - by FractalizeR

  Hello. I wanted to ask you about PHP/Apache configuration methods you know, their pros and cons. I will start myself: ---------------- PHP as Apache module---------------- Pros: good speed since you don't need to start exe every time especially in mpm-worker mode. You can also use various PHP accelerators in this mode like APC or eAccelerator. Cons: if you are running apache in mpm-worker mode, you may face stability issues because every glitch in any php script will lead to unstability to the whole thread pool of that apache process. Also in this mode all scripts are executed on behalf of apache user. This is bad for security. mpm-worker configuration requires PHP compiled in thread-safe mode. At least CentOS and RedHat default repositories doesn't have thread-safe PHP version so on these OSes you need to compile at least PHP yourself (there is a way to activate worker mpm on Apache). The use of thread-safe PHP binaries is considered experimental and unstable. Plus, many PHP extensions does not support thread-safe mode or were not well-tested in thread-safe mode. ---------------- PHP as CGI ---------------- This seems to be the slowest default configuration which seems to be a "con" itself ;) ---------------- PHP as CGI via mod_suphp ---------------- Pros: suphp allows you to execute php scipts on behalf of the script file owner. This way you can securely separate different sites on the same machine. Also, suphp allows to use different php.ini files per virtual host. Cons: PHP in CGI mode means less performance. In this mode you can't use php accelerators like APC because each time new process is spawned to handle script rendering the cache of previous process useless. BTW, do you know the way to apply some accelerator in this config? I heard something about using shm for php bytecode cache. Also, you cannot configure PHP via .htaccess files in this mode. You will need to install PECL htscanner for this if you need to set various per-script options via .htaccess (php_value / php_flag directives) ---------------- PHP as CGI via suexec ---------------- This configuration looks the same as with suphp, but I heard, that it's slower and less safe. Almost same pros and cons apply. ---------------- PHP as FastCGI ---------------- Pros: FastCGI standard allows single php process to handle several scripts before php process is killed. This way you gain performance since no need to spin up new php process for each script. You can also use PHP accelerators in this configuration (see cons section for comment). Also, FCGI almost like suphp also allows php processes to be executed on behalf of some user. mod_fcgid seems to have the most complete fcgi support and flexibility for apache. Cons: The use of php accelerator in fastcgi mode will lead to high memory consumption because each PHP process will have his own bytecode cache (unless there is some accelerator that can use shared memory for bytecode cache. Is there such?). FastCGI is also a little bit complex to configure. You need to create various configuration files and make some configuration modifications. It seems, that fastcgi is the most stable, secure, fast and flexible PHP configuration, however, a bit difficult to be configured. But, may be, I missed something? Comments are welcome!

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• Code runs 6 times slower with 2 threads than with 1

  - by Edward Bird

  So I have written some code to experiment with threads and do some testing. The code should create some numbers and then find the mean of those numbers. I think it is just easier to show you what I have so far. I was expecting with two threads that the code would run about 2 times as fast. Measuring it with a stopwatch I think it runs about 6 times slower! void findmean(std::vector<double>*, std::size_t, std::size_t, double*); int main(int argn, char** argv) { // Program entry point std::cout << "Generating data..." << std::endl; // Create a vector containing many variables std::vector<double> data; for(uint32_t i = 1; i <= 1024 * 1024 * 128; i ++) data.push_back(i); // Calculate mean using 1 core double mean = 0; std::cout << "Calculating mean, 1 Thread..." << std::endl; findmean(&data, 0, data.size(), &mean); mean /= (double)data.size(); // Print result std::cout << " Mean=" << mean << std::endl; // Repeat, using two threads std::vector<std::thread> thread; std::vector<double> result; result.push_back(0.0); result.push_back(0.0); std::cout << "Calculating mean, 2 Threads..." << std::endl; // Run threads uint32_t halfsize = data.size() / 2; uint32_t A = 0; uint32_t B, C, D; // Split the data into two blocks if(data.size() % 2 == 0) { B = C = D = halfsize; } else if(data.size() % 2 == 1) { B = C = halfsize; D = hsz + 1; } // Run with two threads thread.push_back(std::thread(findmean, &data, A, B, &(result[0]))); thread.push_back(std::thread(findmean, &data, C, D , &(result[1]))); // Join threads thread[0].join(); thread[1].join(); // Calculate result mean = result[0] + result[1]; mean /= (double)data.size(); // Print result std::cout << " Mean=" << mean << std::endl; // Return return EXIT_SUCCESS; } void findmean(std::vector<double>* datavec, std::size_t start, std::size_t length, double* result) { for(uint32_t i = 0; i < length; i ++) { *result += (*datavec).at(start + i); } } I don't think this code is exactly wonderful, if you could suggest ways of improving it then I would be grateful for that also.

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• Node.js, Cygwin and Socket.io walk into a bar... Node.js throws ENOBUFS and everyone dies...

  - by A Wizard Did It

  I'm hoping someone here can help me out, I'm not having much luck figuring this out myself. I'm running node.js version 0.3.1 on Cygwin. I'm using Connect and Socket.io. I seem to be having some random problems with DNS or something, I haven't quite figured it out. The end result is that I the server is running fine, but when a browser attempts to connect to it the initial HTTP Request works, Socket.io connects, and then the server dies (output below). I don't think it has anything to do with the HTTP request because the server gets a lot data posted to it, and it was receiving requests and responding up until my connection that killed it. I've googled around and the closest thing I've found is DNS being set improperly. It's a network program meant to run only on an internal network, so I've set the nameserver x.x.x.x in my /etc/resolv.conf to the internal DNS. I've also added nameserver 8.8.8.8 in addition. I'm not sure what else to check, but would be grateful of any help. In node.exe.stackdump Exception: STATUS_ACCESS_VIOLATION at eip=610C51B9 eax=00000000 ebx=00000001 ecx=00000000 edx=00000308 esi=00000000 edi=010FCCB0 ebp=010FCAEC esp=010FCAC4 program=\\?\E:\cygwin\usr\local\bin\node.exe, pid 3296, thread unknown (0xBEC) cs=0023 ds=002B es=002B fs=0053 gs=002B ss=002B Stack trace: Frame Function Args 010FCAEC 610C51B9 (00000000, 00000000, 00000000, 00000000) 010FCBFC 610C5B55 (00000000, 00000000, 00000000, 00000000) 010FCCBC 610C693A (FFFFFFFF, FFFFFFFF, 750334F3, FFFFFFFE) 010FCD0C 61027CB2 (00000002, F4B994D5, 010FCE64, 00000002) 010FCD98 76306B59 (00000002, 010FCDD4, 763069A4, 00000002) End of stack trace Node Output: node.js:50 throw e; // process.nextTick error, or 'error' event on first tick ^ Error: ENOBUFS, No buffer space available at doConnect (net.js:642:19) at net.js:803:9 at dns.js:166:30 at IOWatcher.callback (dns.js:48:15) EDIT I'm hitting an LDAP server using http.createClient immediately after a client connects to get information, and that seems to be where the problem is that is causing ENOBUFS. I've edited the source to include && errno != ENOBUFS which now prevents the server from dying, however now the LDAP request isn't working. I'm not sure what the problem is that would cause that though. As I mentioned this is an internal only application, so I set the DNS servers in /etc/resolv.conf to the DNS servers that are being applied to the host machine. Not sure if this is part of the issue? EDIT 2 Here's some output from gdb --args ./node_g --debug ../myscript.js. I'm not sure if this is related to ENOBUFS, however, as it seems to be disconnecting immediately after connection with Socket.io [New thread 672.0x100] Error: dll starting at 0x76e30000 not found. Error: dll starting at 0x76250000 not found. Error: dll starting at 0x76e30000 not found. Error: dll starting at 0x76f50000 not found. [New thread 672.0xc90] [New thread 672.0x448] debugger listening on port 5858 [New thread 672.0xbf4] 14 Jan 18:48:57 - socket.io ready - accepting connections [New thread 672.0xed4] [New thread 672.0xd68] [New thread 672.0x1244] [New thread 672.0xf14] 14 Jan 18:49:02 - Initializing client with transport "websocket" assertion "b[1] == 0" failed: file "../src/node.cc", line 933, function: ssize_t node::DecodeWrite(char*, size_t, v8::Handle<v8::Value>, node::encoding) Program received signal SIGABRT, Aborted. 0x7724f861 in ntdll!RtlUpdateClonedSRWLock () from /cygdrive/c/Windows/system32/ntdll.dll (gdb) backtrace #0 0x7724f861 in ntdll!RtlUpdateClonedSRWLock () from /cygdrive/c/Windows/system32/ntdll.dll #1 0x7724f861 in ntdll!RtlUpdateClonedSRWLock () from /cygdrive/c/Windows/system32/ntdll.dll #2 0x75030816 in WaitForSingleObjectEx () from /cygdrive/c/Windows/syswow64/KernelBase.dll #3 0x0000035c in ?? () #4 0x00000000 in ?? () (gdb)

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• How to implement wait(); to wait for a notifyAll(); from enter button?

  - by Dakota Miller

  Sorry for the confusion I posted the Worng Logcat info. I updated the question. I want to click Start to start a thread then when enter is clicked i want the thad to continue and get the message and handle the message in the thread then output it to the main thread and update the text view. How would i start a thread to wait for enter to be pressed and get the bundle for the Handler? Here is my Code: public class MainActivity extends Activity implements OnClickListener { Handler mHandler; Button enter; Button start; TextView display; String dateString; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); enter = (Button) findViewById(R.id.enter); start = (Button) findViewById(R.id.start); display = (TextView) findViewById(R.id.Display); enter.setOnClickListener(this); start.setOnClickListener(this); mHandler = new Handler() { <=============================This is Line 31 public void handleMessage(Message msg) { // TODO Auto-generated method stub super.handleMessage(msg); Bundle bundle = msg.getData(); String string = bundle.getString("outKey"); display.setText(string); } }; } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } @Override public void onClick(View v) { // TODO Auto-generated method stub switch (v.getId()) { case R.id.enter: Message msgin = Message.obtain(); Bundle bundlein = new Bundle(); String in = "It Works!"; bundlein.putString("inKey", in); msgin.setData(bundlein); notifyAll(); break; case R.id.start: new myThread().hello.start(); break; } } public class myThread extends Thread { Thread hello = new Thread() { @Override public void run() { // TODO Auto-generated method stub super.run(); Looper.prepare(); try { wait(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } Handler Mhandler = new Handler() { @Override public void handleMessage(Message msg) { // TODO Auto-generated method stub super.handleMessage(msg); Bundle bundle = msg.getData(); dateString = bundle.getString("inKey"); } }; Looper.loop(); Message msg = Message.obtain(); Bundle bundle = new Bundle(); bundle.putString("outKey", dateString); msg.setData(bundle); mHandler.sendMessage(msg); } }; } } Here is the logcat info: 06-27 00:00:24.832: E/AndroidRuntime(18513): FATAL EXCEPTION: Thread-1210 06-27 00:00:24.832: E/AndroidRuntime(18513): java.lang.IllegalMonitorStateException: object not locked by thread before wait() 06-27 00:00:24.832: E/AndroidRuntime(18513): at java.lang.Object.wait(Native Method) 06-27 00:00:24.832: E/AndroidRuntime(18513): at java.lang.Object.wait(Object.java:364) 06-27 00:00:24.832: E/AndroidRuntime(18513): at com .example.learninghandlers.MainActivity$myThread$1.run(MainActivity.java:77)

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• Synchronous communication using NSOperationQueue

  - by chip_munks

  I am new to Objective C programming. I have created two threads called add and display using the NSInvocationOperation and added it on to the NSOperationQueue. I make the display thread to run first and then run the add thread. The display thread after printing the "Welcome to display" has to wait for the results to print from the add method. So i have set the waitUntilFinished method. Both the Operations are on the same queue. If i use waitUntilFinished for operations on the same queue there may be a situation for deadlock to happen(from apples developer documentation). Is it so? To wait for particular time interval there is a method called waitUntilDate: But if i need to like this wait(min(100,dmax)); let dmax = 20; How to do i wait for these conditions? It would be much helpful if anyone can explain with an example. EDITED: threadss.h ------------ #import <Foundation/Foundation.h> @interface threadss : NSObject { BOOL m_bRunThread; int a,b,c; NSOperationQueue* queue; NSInvocationOperation* operation; NSInvocationOperation* operation1; NSConditionLock* theConditionLock; } -(void)Thread; -(void)add; -(void)display; @end threadss.m ------------ #import "threadss.h" @implementation threadss -(id)init { if (self = [super init]) { queue = [[NSOperationQueue alloc]init]; operation = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(display) object:nil]; operation1 = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(add) object:nil]; theConditionLock = [[NSConditionLock alloc]init]; } return self; } -(void)Thread { m_bRunThread = YES; //[operation addDependency:operation1]; if (m_bRunThread) { [queue addOperation:operation]; } //[operation addDependency:operation1]; [queue addOperation:operation1]; //[self performSelectorOnMainThread:@selector(display) withObject:nil waitUntilDone:YES]; //NSLog(@"I'm going to do the asynchronous communication btwn the threads!!"); //[self add]; //[operation addDependency:self]; sleep(1); [queue release]; [operation release]; //[operation1 release]; } -(void)add { NSLog(@"Going to add a and b!!"); a=1; b=2; c = a + b; NSLog(@"Finished adding!!"); } -(void)display { NSLog(@"Into the display method"); [operation1 waitUntilFinished]; NSLog(@"The Result is:%d",c); } @end main.m ------- #import <Foundation/Foundation.h> #import "threadss.h" int main (int argc, const char * argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; threadss* thread = [[threadss alloc]init]; [thread Thread]; [pool drain]; return 0; } This is what i have tried with a sample program. output 2011-06-03 19:40:47.898 threads_NSOperationQueue[3812:1503] Going to add a and b!! 2011-06-03 19:40:47.898 threads_NSOperationQueue[3812:1303] Into the display method 2011-06-03 19:40:47.902 threads_NSOperationQueue[3812:1503] Finished adding!! 2011-06-03 19:40:47.904 threads_NSOperationQueue[3812:1303] The Result is:3 Is the way of invoking the thread is correct. 1.Will there be any deadlock condition? 2.How to do wait(min(100,dmax)) where dmax = 50.

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