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  • Java: Allowing the child thread to kill itself on InterruptedException?

    - by Zombies
    I am using a ThreadPool via ExecutorService. By calling shutDownNow() it interrupts all running threads in the pool. When this happens I want these threads to give up their resources (socket and db connections) and simply die, but without continuing to run anymore logic, eg: inserting anything into the DB. What is the simplest way to achieve this? Bellow is some sample code: public void threadTest() { Thread t = new Thread(new Runnable() { public void run() { try { Thread.sleep(999999); } catch (InterruptedException e) { //invoke thread suicide logic here } } }); t.start(); t.interrupt(); try { Thread.sleep(4000); } catch (InterruptedException e) { } }

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  • What is the fastest (possibly unsafe) way to read a byte[]?

    - by Aidiakapi
    I'm working on a server project in C#, and after a TCP message is received, it is parsed, and stored in a byte[] of exact size. (Not a buffer of fixed length, but a byte[] of an absolute length in which all data is stored.) Now for reading this byte[] I'll be creating some wrapper functions (also for compatibility), these are the signatures of all functions I need: public byte ReadByte(); public sbyte ReadSByte(); public short ReadShort(); public ushort ReadUShort(); public int ReadInt(); public uint ReadUInt(); public float ReadFloat(); public double ReadDouble(); public string ReadChars(int length); public string ReadString(); The string is a \0 terminated string, and is probably encoded in ASCII or UTF-8, but I cannot tell that for sure, since I'm not writing the client. The data exists of: byte[] _data; int _offset; Now I can write all those functions manually, like this: public byte ReadByte() { return _data[_offset++]; } public sbyte ReadSByte() { byte r = _data[_offset++]; if (r >= 128) return (sbyte)(r - 256); else return (sbyte)r; } public short ReadShort() { byte b1 = _data[_offset++]; byte b2 = _data[_offset++]; if (b1 >= 128) return (short)(b1 * 256 + b2 - 65536); else return (short)(b1 * 256 + b2); } public short ReadUShort() { byte b1 = _data[_offset++]; return (short)(b1 * 256 + _data[_offset++]); } But I wonder if there's a faster way, not excluding the use of unsafe code, since this seems a little bit too much work for simple processing.

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  • How are the concepts of process and threads implementated in Linux kernel?

    - by Shan
    Can any one explain how are the concepts of process and threads implemented in Linux kernel ? I am looking for an intuitive explanation with some C snippets ( and important data structures) that clearly distinguishes between the two. I am just looking for the key implementation ideas I should get hold off. Essentially, I want to understand them and implement something similar in an embedded target (not supporte by any OS) in C language.

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  • Crossthread exception and invokerequired solution doesn't change my control value

    - by Pilouk
    EDIT Solution : Here i'm setting my byref value in each object then i'm running a backgroundworker Private Sub TelechargeFichier() Dim DocManquant As Boolean = False Dim docName As String = "" Dim lg As String = "" Dim telechargementFini As Boolean = False lblMessage.Text = EasyDealChangeLanguage.Instance.GetStringFromResourceName("1478") prgBar.Maximum = m_listeFichiers.Count For i As Integer = 0 To m_listeFichiers.Count - 1 m_listeFichiers(i).Set_ByRefLabel(lblMessage) m_listeFichiers(i).Set_ByRefPrgbar(prgBar) m_listeThreads.Add(New Thread(AddressOf m_listeFichiers(i).DownloadMe)) Next m_bgWorker = New BackgroundWorker m_bgWorker.WorkerReportsProgress = True AddHandler m_bgWorker.DoWork, AddressOf DownloadFiles m_bgWorker.RunWorkerAsync() ''Completed 'lblMessage.Text = EasyDealChangeLanguage.Instance.GetStringFromResourceName("1383") 'Me.DialogResult = System.Windows.Forms.DialogResult.OK End Sub Here is my downloadFiles function : Note that each start will do the downloadMe function see below too Private Sub DownloadFiles(sender As Object, e As DoWorkEventArgs) For i As Integer = 0 To m_listeThreads.Count - 1 m_listeThreads(i).Start() Next For i As Integer = 0 To m_listeThreads.Count - 1 m_listeThreads(i).Join() Next End Sub I have multiple thread that each will download a ftp file. I would like that each file that have been completed will set a value to a progress bar and a label from my UI thread. For some reason invokerequired never change to false. Here is my little function that start all the thread Private Sub TelechargeFichier() Dim DocManquant As Boolean = False Dim docName As String = "" Dim lg As String = "" Dim telechargementFini As Boolean = False lblMessage.Text = EasyDealChangeLanguage.Instance.GetStringFromResourceName("1478") prgBar.Maximum = m_listeFichiers.Count For i As Integer = 0 To m_listeFichiers.Count - 1 m_listeFichiers(i).Set_ByRefLabel(lblMessage) m_listeFichiers(i).Set_ByRefPrgbar(prgBar) m_listeThreads.Add(New Thread(AddressOf m_listeFichiers(i).DownloadMe)) Next For i As Integer = 0 To m_listeThreads.Count - 1 m_listeThreads(i).Start() Next For i As Integer = 0 To m_listeThreads.Count - 1 m_listeThreads(i).Join() Next 'Completed lblMessage.Text = EasyDealChangeLanguage.Instance.GetStringFromResourceName("1383") Me.DialogResult = System.Windows.Forms.DialogResult.OK End Sub Here my property that hold the Byref control from the UI thread. This is in my object which content the addressof function that will download the file (DownloadMe) Public Sub Set_ByRefPrgbar(ByRef prgbar As ProgressBar) m_prgBar = prgbar End Sub Public Sub Set_ByRefLabel(ByRef lbl As EasyDeal.Controls.EasyDealLabel3D) m_lblMessage = lbl End Sub Here is the download function : Public Sub DownloadMe() Dim ftpReq As FtpWebRequest Dim ftpResp As FtpWebResponse = Nothing Dim streamInput As Stream Dim fileStreamOutput As FileStream Try ftpReq = CType(WebRequest.Create(EasyDeal.Controls.Common.FTP_CONNECTION & m_downloadFtpPath & m_filename), FtpWebRequest) ftpReq.Credentials = New NetworkCredential(FTP_USER, FTP_PASS) ftpReq.Method = WebRequestMethods.Ftp.DownloadFile ftpResp = ftpReq.GetResponse streamInput = ftpResp.GetResponseStream() fileStreamOutput = New FileStream(m_outputPath, FileMode.Create, FileAccess.ReadWrite) ReadWriteStream(streamInput, fileStreamOutput) Catch ex As Exception 'Au pire la fichier sera pas downloader Finally If ftpResp IsNot Nothing Then ftpResp.Close() End If Dim nomFichier As String = m_displaynameEN If EasyDealChangeLanguage.GetCurrentLanguageTypes = EasyDealChangeLanguage.EnumLanguageType.Francais Then nomFichier = m_displaynameFR End If If m_lblMessage IsNot Nothing Then EasyDealCommon.TH_SetControlText(m_lblMessage, String.Format(EasyDealChangeLanguage.Instance.GetStringFromResourceName("1479"), nomFichier)) End If If m_prgBar IsNot Nothing Then EasyDealCommon.TH_SetPrgValue(m_prgBar, 1) End If End Try End Sub Here is the crossthread invoke solution function : Public Sub TH_SetControlText(ByVal ctl As Control, ByVal text As String) If ctl.InvokeRequired Then ctl.BeginInvoke(New Action(Of Control, String)(AddressOf TH_SetControlText), ctl, text) Else ctl.Text = text End If End Sub Public Sub TH_SetPrgValue(ByVal prg As ProgressBar, ByVal value As Integer) If prg.InvokeRequired Then prg.BeginInvoke(New Action(Of ProgressBar, Integer)(AddressOf TH_SetPrgValue), prg, value) Else prg.Value += value End If End Sub The problem is the invokerequired never get to false it actually goes in to beginInvoke but never end in the Else section to set the value.

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  • How to call a function though Control.BeginInvoke in a signal-slot-like fashion?

    - by Dimitri C.
    I'd like a delegate that calls a function in a different thread when it is invoked. Currently, I'm using the following implementation: delegate void someFunctionDelegate(); //... someFunctionDelegate callBackFunction = someForm.SomeFunction; someForm.Invoke(someFunctionDelegate); However, I'd like a more compact form, combining both the someForm instance and the SomeForm.SomeFunction member function. I'm thinking of something like this: var callBackFunction = new AsynchronousCrossThreadDelegate(someForm, SomeForm.SomeFunction); callBackFunction(); // Should call someForm.BeginInvoke(SomeForm.SomeFunction); Is there a way to do so in C#/.NET? Update I'm looking for a solution that will work for functions with 0 or more parameters.

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  • Is it safe to use a boolean flag to stop a thread from running in C#

    - by Lirik
    My main concern is with the boolean flag... is it safe to use it without any synchronization? I've read in several places that it's atomic. class MyTask { private ManualResetEvent startSignal; private CountDownLatch latch; private bool running; MyTask(CountDownLatch latch) { running = false; this.latch = latch; startSignal = new ManualResetEvent(false); } // A method which runs in a thread public void Run() { startSignal.WaitOne(); while(running) { startSignal.WaitOne(); //... some code } latch.Signal(); } public void Stop() { running = false; startSignal.Set(); } public void Start() { running = true; startSignal.Set(); } public void Pause() { startSignal.Reset(); } public void Resume() { startSignal.Set(); } } Is this a safe way to design a task? Any suggestions, improvements, comments? Note: I wrote my custom CountDownLatch class in case you're wondering where I'm getting it from.

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  • Can I safely bind to data on multi-threaded applications?

    - by Paul
    Hi everyone, I'm trying to solve a classic problem - I have a multi-threaded application which runs some processor-intensive calculations, with a GUI interface. Every time one of the threads has completed a task, I'd like to update a status on a table taskID | status I use DataGridView and BindingList in the following way: BindingList<Task> tasks; dataGridView.DataSource = tasks public class Task : INotifyPropertyChanged { ID{get;} Status{get;set;} } Can a background thread safely update a task's status? and changes will be seen in the correct order in the GUI? Second Question: When do I need to call to PropertyChanged? I tried running with and without the call, didn't seem to bother.. Third Question: I've seen on MSDN that dataGridView uses BindingSource as a mediator between DataGridView.DataSource and BindingList Is this really necessary?

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  • How do I stop Ant from hanging after executing a java program that attempted to interrupt a thread (and failed) and continued?

    - by Zugwalt
    I have Ant build and execute a java program. This program tries to do something that sometimes hangs, so we execute it in a thread. actionThread.start(); try { actionThread.join(10000); } catch (InterruptedException e) { System.out.println("InterruptedException: "+e.getMessage()); } if (actionThread.isAlive()) { actionThread.interrupt(); System.out.println("Thread timed out and never died"); } The ant call looks like this: <java fork="true" failonerror="yes" classname="myPackage.myPathName" classpath="build"> <arg line=""/> <classpath> <pathelement location="bin" /> <fileset dir="lib"> <include name="**/*.jar"/> </fileset> </classpath> </java> And when this runs I see the "Thread timed out and never died" statement, and I also see the main program finish execution, but then Ant just hangs. Presumably it is waiting for the child threads to finish, but they never will. How can I have Ant be done once it is done executing main() and just kill or ignore dead threads?

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  • Mouse move and thread

    - by bsebi
    When I move the mouse over the window, the program runs much faster (cc. 3 times). This is a real time webcam .Net/Mono application running on a MacBook. On Windows works perfect. Is this maybe a power saving function of the laptop? The code: Thread t = new Thread(Foo); t.Priority = ThreadPriority.Highest; // I've tried without priority too, doesn't matter t.Start(); ... void Foo() { while (true) { ++k; // then write k to the window somehow } }

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  • how to call windows paint event from child thread

    - by RAJ K
    If I am wrong then please correct me as I am new in this. I have one thread which display image captured from webcam on a windows created using CreateWindowEx() function. Now when i execute my program I can see that my paint code (in WindowProc()) in never reached (called InvalidateRect() from child thread to redraw), checked using breakpoint. Actually frame capture and display is being done in thread and I think because its in child thread and Window is in Main thread that is why its not able to call paint event. Can you help me on this

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  • Semaphore - What is the use of initial count?

    - by Sandbox
    http://msdn.microsoft.com/en-us/library/system.threading.semaphoreslim.aspx To create a semaphore, I need to provide an initial count and maximum count. MSDN states that an initial count is - The initial number of requests for the semaphore that can be granted concurrently. While it states that maximum count is The maximum number of requests for the semaphore that can be granted concurrently. I can understand that the maximum count is the maximum number of threads that can access a resource concurrently. But, what is the use of initial count? If I create a semaphore with an initial count of 0 and a maximum count of 2, none of my threadpool threads are able to access the resource. If I set the initial count as 1 and maximum count as 2 then only thread pool thread can access the resource. It is only when I set both initial count and maximum count as 2, 2 threads are able to access the resource concurrently. So, I am really confused about the significance of initial count? SemaphoreSlim semaphoreSlim = new SemaphoreSlim(0, 2); //all threadpool threads wait SemaphoreSlim semaphoreSlim = new SemaphoreSlim(1, 2);//only one thread has access to the resource at a time SemaphoreSlim semaphoreSlim = new SemaphoreSlim(2, 2);//two threadpool threads can access the resource concurrently

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  • How solve consumer/producer task using semaphores

    - by user1074896
    I have SimpleProducerConsumer class that illustrate consumer/producer problem (I am not sure that it's correct). public class SimpleProducerConsumer { private Stack<Object> stack = new Stack<Object>(); private static final int STACK_MAX_SIZE = 10; public static void main(String[] args) { SimpleProducerConsumer pc = new SimpleProducerConsumer(); new Thread(pc.new Producer(), "p1").start(); new Thread(pc.new Producer(), "p2").start(); new Thread(pc.new Consumer(), "c1").start(); new Thread(pc.new Consumer(), "c2").start(); new Thread(pc.new Consumer(), "c3").start(); } public synchronized void push(Object d) { while (stack.size() >= STACK_MAX_SIZE) try { wait(); } catch (InterruptedException e) { e.printStackTrace(); } try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } stack.push(new Object()); System.out.println("push " + Thread.currentThread().getName() + " " + stack.size()); notify(); } public synchronized Object pop() { while (stack.size() == 0) try { wait(); } catch (InterruptedException e) { e.printStackTrace(); } try { Thread.sleep(50); } catch (InterruptedException e) { e.printStackTrace(); } stack.pop(); System.out.println("pop " + Thread.currentThread().getName() + " " + stack.size()); notify(); return null; } class Consumer implements Runnable { @Override public void run() { while (true) { pop(); } } } class Producer implements Runnable { @Override public void run() { while (true) { push(new Object()); } } } } I found simple realization of semaphore(here:http://docs.oracle.com/javase/tutorial/essential/concurrency/guardmeth.html I know that there is concurrency package) How I need to change code to exchange java objects monitors to my custom semaphore. (To illustrate C/P problem using semaphores) Semaphore: class Semaphore { private int counter; public Semaphore() { this(0); } public Semaphore(int i) { if (i < 0) throw new IllegalArgumentException(i + " < 0"); counter = i; } public synchronized void release() { if (counter == 0) { notify(); } counter++; } public synchronized void acquire() throws InterruptedException { while (counter == 0) { wait(); } counter--; } }

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  • MonoTouch Load image in background

    - by user1058951
    I am having a problem trying to load an image and display it using System.Threading.Task My Code is as follows Task DownloadTask { get; set; } public string Instrument { get; set; } public PriceChartViewController(string Instrument) { this.Instrument = Instrument; DownloadTask = Task.Factory.StartNew(() => { }); } private void LoadChart(ChartType chartType) { NSData data = new NSData(); DownloadTask = DownloadTask.ContinueWith(prevTask => { try { UIApplication.SharedApplication.NetworkActivityIndicatorVisible = true; NSUrl nsUrl = new NSUrl(chartType.Uri(Instrument)); data = NSData.FromUrl(nsUrl); } finally { UIApplication.SharedApplication.NetworkActivityIndicatorVisible = false; } }); DownloadTask = DownloadTask.ContinueWith(t => { UIImage image = new UIImage(data); chartImageView = new UIImageView(image); chartImageView.ContentScaleFactor = 2f; View.AddSubview(chartImageView); this.Title = chartType.Title; }, CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, TaskScheduler.FromCurrentSynchronizationContext()); } The second Continue with does not seem to be being called? Initially my code looked like the following without the background processing and it worked perfectly. private void oldLoadChart(ChartType chartType) { UIApplication.SharedApplication.NetworkActivityIndicatorVisible = true; NSUrl nsUrl = new NSUrl(chartType.Uri(Instrument)); NSData data = NSData.FromUrl(nsUrl); UIImage image = new UIImage(data); chartImageView = new UIImageView(image); chartImageView.ContentScaleFactor = 2f; View.AddSubview(chartImageView); this.Title = chartType.Title; UIApplication.SharedApplication.NetworkActivityIndicatorVisible = false; } Does anyone know what I am doing wrong?

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  • Download multiple files in background in Android

    - by Addev
    Basically I'm trying to make a little app for watching offline content. So there's a moment where the user selects to download the contents (and the app should download about 300 small files and images). I'd like to show the user how does the process go if he enters the proper activity. Showing a list of all the files, telling what has been already downloaded, in progress or waiting for download. My problem is that I really don't know what approach to take for achieve this. Since the download should last until finished I imagine the solution is an Service, but whats best? an IntentService, a Bound Service or an Standard Service calling a startService() for each download? And how can I keep my objects updated for displaying them later? should I use a database or objects in memory? Thanks

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  • memcpy() safety on adjacent memory regions

    - by JaredC
    I recently asked a question on using volatile and was directed to read some very informative articles from Intel and others discussing memory barriers and their uses. After reading these articles I have become quite paranoid though. I have a 64-bit machine. Is it safe to memcpy into adjacent, non-overlapping regions of memory from multiple threads? For example, say I have a buffer: char buff[10]; Is it always safe for one thread to memcpy into the first 5 bytes while a second thread copies into the last 5 bytes? My gut reaction (and some simple tests) indicate that this is completely safe, but I have been unable to find documentation anywhere that can completely convince me.

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  • Error with threads during automatic testing on TeamCity 5

    - by yeyeyerman
    Hello, I'm having some problems executing the tests of the application I'm developing. All the tests execute normally with ReSharper and in NCover. However, the execution of one of these tests in TeamCity is generating an error. This test initializes two objects, the object under test and a simulator of a real object. Both objects will communicate throug a serial link in a representation of the real scenario. ObjectSimulator r_simulator = new ObjectSimulator(...); ObjectDriver r_driver = new ObjectDriver(...); Assert.IsTrue(r_driver.Connect() == ErrorCode.Success); The simulator just do the following in the constructor public class ObjectSimulator { ... public ObjectSimulator() { // serial port configuration m_port = new SerialPort(); m_port.DataReceived += DataReceivedEvent; } ... } The main object has two threads. The main thread of the application and a timer to refresh a watchdog timer in the real object. public ErrorCode Connect() { ... StartSynchroTimer(); Thread.Sleep(4); // to check if the timer is working properly ... } The problem is comming from the Thread.Sleep() call, as when I remove it everything works. It seems like the ObjectSimulator also sleeps and doesn't receive the DataReceived event. How can I resolve this issue?

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  • Fast inter-process (inter-threaded) communications IPC on large multi-cpu system.

    - by IPC
    What would be the fastest portable bi-directional communication mechanism for inter-process communication where threads from one application need to communicate to multiple threads in another application on the same computer, and the communicating threads can be on different physical CPUs). I assume that it would involve a shared memory and a circular buffer and shared synchronization mechanisms. But shared mutexes are very expensive (and there are limited number of them too) to synchronize when threads are running on different physical CPUs.

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  • C# WinForms populating TreeView from List<myObj>

    - by user743354
    I have this structure of classes: public class L3Message { public int Number { get; set; } public string MessageName { get; set; } public string Device { get; set; } public string Time { get; set; } public string ScramblingCode { get; set; } public List<Parameter> Parameters { get; set; } public L3Message() { Parameters = new List<Parameter>(); } } public class Parameter { public int numOfWhitespaces { get; set; } public string ParameterName { get; set; } public string ParameterValue { get; set; } public Parameter Parent { get; set; } public List<Parameter> SubParameters { get; set; } public Parameter() { SubParameters = new List<Parameter>(); } } So, as return type from one of my Methods I have List of L3Messages (List < L3Message ), and I need to map that to TreeView in WinForms (populate TreeView from that List). If possible, I would like to that in separate thread. How can I achieve that?

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  • Does thread pool size keep growing for scheduledthreadpoolexecutor?

    - by Sourajit Basak
    Imagine a situation where tasks are being added to scheduledthreadpoolexecutor. Each of these tasks will keep on running at different periodic intervals. Although all such tasks will not be running at the same time because each is set at different intervals, there may be a situation where a high number of threads are competing for execution. Is there any restriction on total number of threads ? It seems there is a restriction on the total number of idle threads. And does this concept of idle thread imply that long running tasks (thread) may be destroyed and recreated when needed ?

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  • Turn based synchronization between threads

    - by Amarus
    I'm trying to find a way to synchronize multiple threads having the following conditions: * There are two types of threads: 1. A single "cyclic" thread executing an infinite loop to do cyclic calculations 2. Multiple short-lived threads not started by the main thread * The cyclic thread has a sleep duration between each cycle/loop iteration * The other threads are allowed execute during the inter-cycle sleep of the cyclic thread: - Any other thread that attempts to execute during an active cycle should be blocked - The cyclic thread will wait until all other threads that are already executing to be finished Here's a basic example of what I was thinking of doing: // Somewhere in the code: ManualResetEvent manualResetEvent = new ManualResetEvent(true); // Allow Externally call CountdownEvent countdownEvent = new CountdownEvent(1); // Can't AddCount a CountdownEvent with CurrentCount = 0 void ExternallyCalled() { manualResetEvent.WaitOne(); // Wait until CyclicCalculations is having its beauty sleep countdownEvent.AddCount(); // Notify CyclicCalculations that it should wait for this method call to finish before starting the next cycle Thread.Sleep(1000); // TODO: Replace with actual method logic countdownEvent.Signal(); // Notify CyclicCalculations that this call is finished } void CyclicCalculations() { while (!stopCyclicCalculations) { manualResetEvent.Reset(); // Block all incoming calls to ExternallyCalled from this point forward countdownEvent.Signal(); // Dirty workaround for the issue with AddCount and CurrentCount = 0 countdownEvent.Wait(); // Wait until all of the already executing calls to ExternallyCalled are finished countdownEvent.Reset(); // Reset the CountdownEvent for next cycle. Thread.Sleep(2000); // TODO: Replace with actual method logic manualResetEvent.Set(); // Unblock all threads executing ExternallyCalled Thread.Sleep(1000); // Inter-cycles delay } } Obviously, this doesn't work. There's no guarantee that there won't be any threads executing ExternallyCalled that are in between manualResetEvent.WaitOne(); and countdownEvent.AddCount(); at the time the main thread gets released by the CountdownEvent. I can't figure out a simple way of doing what I'm after, and almost everything that I've found after a lengthy search is related to producer/consumer synchronization which I can't apply here.

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