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• Ruby Multithreading: making one thread wait for a signal from another

  - by Peter

  In Ruby, I want to have two threads running at the same time, and want the background thread to periodically signal the foreground thread. How do I get the foreground thread to block until the background thread says 'go'? I can think of a few ways to do it, but am after the most appropriate, idiomatic Ruby method. In code: loop do # background, thread 1 sleep 3 receive_input # tell foreground input is ready # <-- how do I do this? end and loop do # foreground, thread 2 wait_for_signal_from_background # <-- how do I do this? do_something end

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• Issue with maxWorkerThreads and thread count

  - by Kartik M

  I have created an ASP.NET application which creates threads in an infinite loop. I set maxWorkerThreads to 20 in processModel in machine.config. When I checked the Thread count in perfmon there was around 7000 threads created in worker process. In PageLoad() I have: using System.Threading; ... int count = 0; var threadList = new System.Collections.Generic.List<System.Threading.Thread>(); try { while (true) { Thread newThread = new Thread(ThreadStart(DummyCall), 1024); newThread.Start(); threadList.Add(newThread); count++; } } catch (Exception ex) { Response.Write(count + " : " + ex.ToString()); } Function: void DummyCall() { System.Threading.Thread.Sleep(1000000000); } How do I restrict thread creation in ASP.NET with IIS6/7?

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• C# threading a FolderBrowserDialog

  - by Marthin

  Hi, Im trying to use the FolderBrowserDialog to select a folder in C#. At first I got a Thread exception, so I googled what was wrong and fixed that but now im stuck at a nother problem. I whant to know when a folder has been selected. This is what i'v got right now. private void btnWorkingFolder_Click(object sender, EventArgs e) { var t = new Thread(SelectFolder); t.IsBackground = true; t.SetApartmentState(ApartmentState.STA); t.Start(); } private void SelectFolder() { FolderBrowserDialog dialog = new FolderBrowserDialog(); if (dialog.ShowDialog() == DialogResult.OK) { txtWorkFolder.Text = dialog.SelectedPath; } } } The problem here is that i cant Set the Text for txtWorkingFolder since im not in the same thread. I dont want to change the thread for txtWorkingFolder, so my question is this, how do I change it's value from the new thread once the DialogResult.OK has been set? Thx for any help! /Marthin

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• dealloc on Background Thread

  - by Mark Brackett

  Is it an error to call dealloc on a UIViewController from a background thread? It seems that UITextView (can?) eventually call _WebTryThreadLock which results in: bool _WebTryThreadLock(bool): 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. Background: I have a subclassed NSOperation that takes a selector and a target object to notify. -(id)initWithTarget:(id)target { if (self = [super init]) { _target = [target retain]; } return self; } -(void)dealloc { [_target release]; [super dealloc]; } If the UIViewController has already been dismissed when the NSOperation gets around to running, then the call to release triggers it's dealloc on a background thread.

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• WCF Service with callbacks coming from background thread?

  - by Mark Struzinski

  Here is my situation. I have written a WCF service which calls into one of our vendor's code bases to perform operations, such as Login, Logout, etc. A requirement of this operation is that we have a background thread to receive events as a result of that action. For example, the Login action is sent on the main thread. Then, several events are received back from the vendor service as a result of the login. There can be 1, 2, or several events received. The background thread, which runs on a timer, receives these events and fires an event in the wcf service to notify that a new event has arrived. I have implemented the WCF service in Duplex mode, and planned to use callbacks to notify the UI that events have arrived. Here is my question: How do I send new events from the background thread to the thread which is executing the service? Right now, when I call OperationContext.Current.GetCallbackChannel<IMyCallback>(), the OperationContext is null. Is there a standard pattern to get around this? I am using PerSession as my SessionMode on the ServiceContract. UPDATE: I thought I'd make my exact scenario clearer by demonstrating how I'm receiving events from the vendor code. My library receives each event, determines what the event is, and fires off an event for that particular occurrence. I have another project which is a class library specifically for connecting to the vendor service. I'll post the entire implementation of the service to give a clearer picture: [ServiceBehavior( InstanceContextMode = InstanceContextMode.PerSession )] public class VendorServer:IVendorServer { private IVendorService _vendorService; // This is the reference to my class library public VendorServer() { _vendorServer = new VendorServer(); _vendorServer.AgentManager.AgentLoggedIn += AgentManager_AgentLoggedIn; // This is the eventhandler for the event which arrives from a background thread } public void Login(string userName, string password, string stationId) { _vendorService.Login(userName, password, stationId); // This is a direct call from the main thread to the vendor service to log in } private void AgentManager_AgentLoggedIn(object sender, EventArgs e) { var agentEvent = new AgentEvent { AgentEventType = AgentEventType.Login, EventArgs = e }; } } The AgentEvent object contains the callback as one of its properties, and I was thinking I'd perform the callback like this: agentEvent.Callback = OperationContext.Current.GetCallbackChannel<ICallback>(); How would I pass the OperationContext.Current instance from the main thread into the background thread?

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• How does the event dispatch thread work?

  - by Roman

  With the help of people on stackoverflow I was able to get the following working code of the simples GUI countdown (it just displays a window counting down seconds). My main problem with this code is the invokeLater stuff. As far as I understand the invokeLater send a task to the event dispatching thread (EDT) and then the EDT execute this task whenever it "can" (whatever it means). Is it right? To my understanding the code works like that: In the main method we use invokeLater to show the window (showGUI method). In other words, the code displaying the window will be executed in the EDT. In the main method we also start the counter and the counter (by construction) is executed in another thread (so it is not in the event dispatching thread). Right? The counter is executed in a separate thread and periodically it calls updateGUI. The updateGUI is supposed to update GUI. And GUI is working in the EDT. So, updateGUI should also be executed in the EDT. It is why the code for the updateGUI is inclosed in the invokeLater. Is it right? What is not clear to me is why we call the counter from the EDT. Anyway it is not executed in the EDT. It starts immediately a new thread and the counter is executed there. So, why we cannot call the counter in the main method after the invokeLater block? import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.SwingUtilities; public class CountdownNew { static JLabel label; // Method which defines the appearance of the window. public static void showGUI() { JFrame frame = new JFrame("Simple Countdown"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); label = new JLabel("Some Text"); frame.add(label); frame.pack(); frame.setVisible(true); } // Define a new thread in which the countdown is counting down. public static Thread counter = new Thread() { public void run() { for (int i=10; i>0; i=i-1) { updateGUI(i,label); try {Thread.sleep(1000);} catch(InterruptedException e) {}; } } }; // A method which updates GUI (sets a new value of JLabel). private static void updateGUI(final int i, final JLabel label) { SwingUtilities.invokeLater( new Runnable() { public void run() { label.setText("You have " + i + " seconds."); } } ); } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { showGUI(); counter.start(); } }); } }

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• Facebook API returning wrong unread thread count

  - by houbysoft

  I'm trying to query the thread FQL table to get all unread messages, and also the count of unread items in the thread. This is how I query the table: SELECT thread_id,updated_time,snippet,snippet_author,unread FROM thread WHERE folder_id=0 AND unread!=0 From reading the doc to which I linked above, it seems to me that unread should include the count of unread messages in the thread. However, I just tested the above call and Facebook gives me back a value of unread=1, despite the thread in question having 4 unread items. This is how the thread looks on facebook.com (notice the (4), showing that unread should be 4): This is what the API returns to me, which is wrong (notice the "unread":1): { "data":[ { "name":"messages", "fql_result_set":[ { "thread_id":"BLAH BLAH BLAH", "updated_time":1333317140, "snippet":"BLAH BLAH BLAH", "snippet_author":BLAH, "unread":1 } ] } ] } Am I doing something wrong, or is this a bug?

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• iPhone: One Object, One Thread

  - by GingerBreadMane

  On the iPhone, I would like to do some operations on an image in a separate thread. Rather than dealing with semiphores, locking, etc., I'd like to use the 'One Object, One Thread' method of safely writing this concurrent operation. I'm not sure what is the correct way to copy my object into a new thread so that the object is not accessed in the main thread. Do I use the 'copy' method? If so, do I do this before the thread or inside the thread? ... -(void)someMethod{ UIImage *myImage; [NSThread detachNewThreadSelector:@selector(getRotatedImage:) toTarget:self withObject:myImage]; } -(void)getRotatedImage:(UIImage *)image{ ... ... UIImage *copiedImage = [image copy]; ... ... }

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• How does one implement a truly asynchronous java thread

  - by Ritesh M Nayak

  I have a function that needs to perfom two operations, one which finishes fast and one which takes a long time to run. I want to be able to delegate the long running operation to a thread and I dont care when the thread finishes, but the threads needs to complete. I implemented this as shown below , but, my secondoperation never gets done as the function exits after the start() call. How I can ensure that the function returns but the second operation thread finishes its execution as well and is not dependent on the parent thread ? public void someFunction(String data) { smallOperation() Blah a = new Blah(); Thread th = new Thread(a); th.Start(); } class SecondOperation implements Runnable { public void run(){ // doSomething long running } }

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• How can I synchronize database access between a write-thread and a read-thread?

  - by Runcible

  My program has two threads: Main execution thread that handles user input and queues up database writes A utility thread that wakes up every second and flushes the writes to the database Inside the main thread, I occasionally need to make reads on the database. When this happens, performance is not important, but correctness is. (In a perfect world, I would be reading from a cache, not making a round-trip to the database - but let's put that aside for the sake of discussion.) How do I make sure that the main thread sees a correct / quiescent database? A standard mutex won't work, since I run the risk of having the main thread grab the mutex before the data gets flushed to the database. This would be a big race condition. What I really want is some sort of mutex that lets the main thread of execution proceed only AFTER the mutex has been grabbed and released once. Does such a thing exist? What's the best way to solve this problem?

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• Putting a thread to sleep until event X occurs

  - by tipu

  I'm writing to many files in a threaded app and I'm creating one handler per file. I have HandlerFactory class that manages the distribution of these handlers. What I'd like to do is that thread A requests and gets foo.txt's file handle from the HandlerFactory class thread B requests foo.txt's file handler handler class recognizes that this file handle has been checked out handler class puts thread A to sleep thread B closes file handle using a wrapper method from HandlerFactory HandlerFactory notifies sleeping threads thread B wakes and successfully gets foo.txt's file handle This is what I have so far, def get_handler(self, file_path, type): self.lock.acquire() if file_path not in self.handlers: self.handlers[file_path] = open(file_path, type) elif not self.handlers[file_path].closed: time.sleep(1) self.lock.release() return self.handlers[file_path][type] I believe this covers the sleeping and handler retrieval successfully, but I am unsure how to wake up all threads, or even better wake up a specific thread.

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• Start a thread using a method pointer

  - by Michael

  Hi ! I'm trying to develop a thread abstraction (POSIX thread and thread from the Windows API), and I would very much like it to be able to start them with a method pointer, and not a function pointer. What I would like to do is an abstraction of thread being a class with a pure virtual method "runThread", which would be implanted in the future threaded class. I don't know yet about the Windows thread, but to start a POSIX thread, you need a function pointer, and not a method pointer. And I can't manage to find a way to associate a method with an instance so it could work as a function. I probably just can't find the keywords (and I've been searching a lot), I think it's pretty much what Boost::Bind() does, so it must exist. Can you help me ?

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• [C++] Start a thread using a method pointer

  - by Michael

  Hi ! I'm trying to develop a thread abstraction (POSIX thread and thread from the Windows API), and I would very much like it to be able to start them with a method pointer, and not a function pointer. What I would like to do is an abstraction of thread being a class with a pure virtual method "runThread", which would be implanted in the future threaded class. I don't know yet about the Windows thread, but to start a POSIX thread, you need a function pointer, and not a method pointer. And I can't manage to find a way to associate a method with an instance so it could work as a function. I probably just can't find the keywords (and I've been searching a lot), I think it's pretty much what Boost::Bind() does, so it must exist. Can you help me ?

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• Threading in java vs C#

  - by ffayyaz

  I need a little confirmation over something i am confused at . I know how threads work in java. new DialList(string a , string b).start(); // where DialList is a class public class DialList extends Thread { public DialList(String a, string b) { FilePath = a; ThreadLogFile = b"; } public void run() { // some code to run in different thread } } Now i want to run same code in C# , Shall i put the code which is in run() into a method and do something like Thread t = new Thread (runcsharp); // Kick off a new thread t.Start(); static void runcsharp() { // code } or is there some other way to do it ?

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• Running a loop (such as one for a mock webserver) within a thread

  - by bob c

  I'm trying to run a mock webserver within a thread within a class. I've tried passing the class' @server property to the thread block but as soon as I try to do server.accept the thread stops. Is there some way to make this work? I want to basically be able to run a webserver off of this script while still taking user input via stdin.gets. Is this possible? class Server def initialize() @server = TCPServer.new(8080) end def run() @thread = Thread.new(@server) { |server| while true newsock = server.accept puts "some stuff after accept!" next if !newsock # some other stuff end } end end def processCommand() # some user commands here end test = Server.new while true do processCommand(STDIN.gets) end In the above sample, the thread dies on server.accept

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• What will or won't cause a thread to block (a question from a test)

  - by fingerprint211b

  I've had a test, and there was a question I lost some points on, because I wasn't able to answer it : Which of the following is NOT a condition which can cause a thread to block : Calling an objects's wait() method Waiting for an I/O operation Calling sleep() Calling yield() Calling join() As far as I know, all of these are blocking calls : wait() returns when an something calls notify(), blocks until then If the thread is WAITING for an I/O operation then it's obviously blocked sleep(), obviously, blocks until the time runs out, or something wakes up the thread yield() "cancels the rest of the thread's timeslice" (lacking a better term), and returns only when the thread is active again join() blocks until the thread it's waiting for terminates. Am I missing something here?

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• Windows App. Thread Aborting Issue

  - by Patrick

  I'm working on an application that has to make specific decisions based on files that are placed into a folder being watched by a file watcher. Part of this decision making process involves renaming files before moving them off to another folder to be processed. Since I'm working with files of all different sizes I created an object that checks the file in a seperate thread to verify that it is "available" and when it is it fires an event. When I run the rename code from inside this available event it works. public void RenameFile_Test() { string psFilePath = @"C:\File1.xlsx"; tgt_File target = new FileObject(psFilePath); target.FileAvailable += new FileEventHandler(OnFileAvailable); target.FileUnAvailable += new FileEventHandler(OnFileUnavailable); } private void OnFileAvailable(object source, FileEventArgs e) { ((FileObject)source).RenameFile(@"C:\File2.xlsx"); } The problem I'm running into is that when the extensions are different from the source file and the rename to file I am making a call to a conversion factory that returns a factory object based on the type of conversion and then converts the file accordingly before doing the rename. When I run that particular piece of code in unit test it works, the factory object is returned, and the conversion happens correctly. But when I run it within the process I get up to the... moExcelApp = new Application(); part of converting an .xls or .xlsx to a .csv and i get a "Thread was being Aborted" error. Any thoughts? Update: There is a bit more information and a bit of map of how the application works currently. Client Application running FSW On File Created event Creates a FileObject passing in the path of the file. On construction the file is validated: if file exists is true then, Thread toAvailableCheck = new Thread(new ThreadStart(AvailableCheck)); toAvailableCheck.Start(); The AvailableCheck Method repeatedly tries to open a streamreader to the file until the reader is either created or the number of attempts times out. If the reader is opened, it fires the FileAvailable event, if not it fires the FileUnAvailable event, passing back itself in the event. The client application is wired to catch those events from inside the Oncreated event of the FSW. the OnFileAvailable method then calls the rename functionality which contains the excel interop call. If the file is being renamed (not converted, extensions stay the same) it does a move to change the name from the old file name to the new, and if its a conversion it runs a conversion factory object which returns the correct type of conversion based on the extensions of the source file and the destination file name. If it is a simple rename it works w/o a problem. If its a conversion (which is the XLS to CSV object that is returned as a part of the factory) the very first thing it does is create a new application object. That is where the application bombs. When i test the factory and conversion/rename process outside of the thread and in its own unit test the process works w/o a problem. Update: I tested the Excel Interop inside a thread by doing this: [TestMethod()] public void ExcelInteropTest() { Thread toExcelInteropThreadTest = new Thread(new ThreadStart(Instantiate_App)); toExcelInteropThreadTest.Start(); } private void Instantiate_App() { Application moExcelApp = new Application(); moExcelApp.Quit(); } And on the line where the application is instatntiated I got the 'A first chance exception of type 'System.Threading.ThreadAbortException' error. So I added; toExcelInteropThreadTest.SetApartmentState(ApartmentState.MTA); after the thread instantiation and before the thread start call and still got the same error. I'm getting the notion that I'm going to have to reconsider the design.

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• An unspecified error occurred on the render thread. (NotifyPartitionIsZombie)

  - by red-X

  oke heres the problem, I have a ContentControl3D object from thriple in that im creating a LibraryStack with images it runs fine, until i run the function where the LibraryStack gets created and filled. when i click on any of the objects inside i get the following error An unspecified error occurred on the render thread. with stacktrace at System.Windows.Media.MediaContext.NotifyPartitionIsZombie(Int32 failureCode) at System.Windows.Media.MediaContext.NotifyChannelMessage() at System.Windows.Interop.HwndTarget.HandleMessage(Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Interop.HwndSource.HwndTargetFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter) at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) at System.Windows.Threading.Dispatcher.WrappedInvoke(Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) at System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Boolean isSingleParameter) at System.Windows.Threading.Dispatcher.Invoke(DispatcherPriority priority, Delegate method, Object arg) at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam) at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg) at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame) at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame) at System.Windows.Threading.Dispatcher.Run() at System.Windows.Application.RunDispatcher(Object ignore) at System.Windows.Application.RunInternal(Window window) at System.Windows.Application.Run(Window window) at System.Windows.Application.Run() at WelkoMap.App.Main() in F:\MediaGarde\Surface\Development\WelkoMap\WelkoMap\obj\Debug\App.g.cs:line 0 at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args) at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args) at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() at System.Threading.ThreadHelper.ThreadStart_Context(Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ThreadHelper.ThreadStart() heres the code that adds and creates the LibraryStack and fills it public void ReplaceBackContent(List<Image> images, List<MediaElement> videos) { ContentControl3D control = this.TryFindParent<ContentControl3D>(); if (control == null) { return; } LibraryStack stack = new LibraryStack(); foreach (Image image in images) { if (image.Parent != null) { continue; } LibraryStackItem item = new LibraryStackItem(); item.Content = image; stack.Items.Add(item); } control.BackContent = stack; } Since it has the NotifyPartitionIsZombie error i already installed windows update KB967634 which had absolutely no effect at all

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• 500 Worker Threads, what kind of thread pool?

  - by Submerged

  I am wondering if this is the best way to do this. I have about 500 threads that run indefinitely, but Thread.sleep for a minute when done one cycle of processing. ExecutorService es = Executors.newFixedThreadPool(list.size()+1); for (int i = 0; i < list.size(); i++) { es.execute(coreAppVector.elementAt(i)); //coreAppVector is a vector of extends thread objects } The code that is executing is really simple and basically just this class aThread extends Thread { public void run(){ while(true){ Thread.sleep(ONE_MINUTE); //Lots of computation every minute } } } I do need a separate threads for each running task, so changing the architecture isn't an option. I tried making my threadPool size equal to Runtime.getRuntime().availableProcessors() which attempted to run all 500 threads, but only let 8 (4xhyperthreading) of them execute. The other threads wouldn't surrender and let other threads have their turn. I tried putting in a wait() and notify(), but still no luck. If anyone has a simple example or some tips, I would be grateful! Well, the design is arguably flawed. The threads implement Genetic-Programming or GP, a type of learning algorithm. Each thread analyzes advanced trends makes predictions. If the thread ever completes, the learning is lost. That said, I was hoping that sleep() would allow me to share some of the resources while one thread isn't "learning"

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• Exception calling remote SOAP call from thread

  - by Duncan

  This is an extension / next step of this question I asked a few minutes ago. I've a Delphi application with a main form and a thread. Every X seconds the thread makes a web services request for a remote object. It then posts back to the main form which handles updating the UI with the new information. I was previously using a TTimer object in my thread, and when the TTimer callback function ran, it ran in the context of the main thread (but the remote web services request did work). This rather defeated the purpose of the separate thread, and so I now have a simple loop and sleep routine in my thread's Execute function. The problem is, an exception is thrown when returning from GetIMySOAPService(). procedure TPollingThread.Execute; var SystemStatus : TCWRSystemStatus; begin while not Terminated do begin sleep(5000); try SystemStatus := GetIMySOAPService().GetSystemStatus; PostMessage( ParentHandle, Integer(apiSystemStatus), Integer(SystemStatus), 0 ); SystemStatus.DataContext := nil; LParam(SystemStatus) := 0; except end; end; end; Can anyone advise as to why this exception is being thrown when calling this function from the thread? I'm sure I'm overlooking something fundamental and simple. Thanks, Duncan

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• how to restart a Thread?

  - by wizztjh

  It is a RMI Server object , so many sethumanActivity() might be run , how do i make sure the previous changeToFalse thread will be stop or halt before the new changeToFalse run? t. interrupt ? Basically when sethumanActivity() is invoke , the humanActivity will be set to true , but a thread will be run to set it back to false. But I am thinking for how to disable or kill the thread when another sethumanActivity() invoked? public class VitaminDEngine implements VitaminD { public boolean humanActivity = false; changeToFalse cf = new changeToFalse(); Thread t = new Thread(cf); private class changeToFalse implements Runnable{ @Override public void run() { try { Thread.sleep(4000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } humanActivity = false; } } @Override public void sethumanActivity() throws RemoteException { // TODO Auto-generated method stub humanActivity = true; t.start(); } public boolean gethumanActivity() throws RemoteException { // TODO Auto-generated method stub return humanActivity; } } Edited after the help of SOer package smartOfficeJava; import java.rmi.RemoteException; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class VitaminDEngine implements VitaminD { public volatile boolean humanActivity = false; changeToFalse cf = new changeToFalse(); ExecutorService service = Executors.newSingleThreadExecutor(); private class changeToFalse implements Runnable{ @Override public void run() { try { Thread.sleep(4000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } humanActivity = false; } } @Override public synchronized void sethumanActivity() throws RemoteException { humanActivity = true; service.submit(cf); } public synchronized boolean gethumanActivity() throws RemoteException { return humanActivity; } }

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• python can't start a new thread

  - by Giorgos Komnino

  I am building a multi threading application. I have setup a threadPool. [ A Queue of size N and N Workers that get data from the queue] When all tasks are done I use tasks.join() where tasks is the queue . The application seems to run smoothly until suddently at some point (after 20 minutes in example) it terminates with the error thread.error: can't start new thread Any ideas? Edit: The threads are daemon Threads and the code is like: while True: t0 = time.time() keyword_statuses = DBSession.query(KeywordStatus).filter(KeywordStatus.status==0).options(joinedload(KeywordStatus.keyword)).with_lockmode("update").limit(100) if keyword_statuses.count() == 0: DBSession.commit() break for kw_status in keyword_statuses: kw_status.status = 1 DBSession.commit() t0 = time.time() w = SWorker(threads_no=32, network_server='http://192.168.1.242:8180/', keywords=keyword_statuses, cities=cities, saver=MySqlRawSave(DBSession), loglevel='debug') w.work() print 'finished' When the daemon threads are killed? When the application finishes or when the work() finishes? Look at the thread pool and the worker (it's from a recipe ) from Queue import Queue from threading import Thread, Event, current_thread import time event = Event() class Worker(Thread): """Thread executing tasks from a given tasks queue""" def __init__(self, tasks): Thread.__init__(self) self.tasks = tasks self.daemon = True self.start() def run(self): '''Start processing tasks from the queue''' while True: event.wait() #time.sleep(0.1) try: func, args, callback = self.tasks.get() except Exception, e: print str(e) return else: if callback is None: func(args) else: callback(func(args)) self.tasks.task_done() class ThreadPool: """Pool of threads consuming tasks from a queue""" def __init__(self, num_threads): self.tasks = Queue(num_threads) for _ in range(num_threads): Worker(self.tasks) def add_task(self, func, args=None, callback=None): ''''Add a task to the queue''' self.tasks.put((func, args, callback)) def wait_completion(self): '''Wait for completion of all the tasks in the queue''' self.tasks.join() def broadcast_block_event(self): '''blocks running threads''' event.clear() def broadcast_unblock_event(self): '''unblocks running threads''' event.set() def get_event(self): '''returns the event object''' return event

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• Android: Error trying to edit button text after thread sleep

  - by Vass

  (programming Android in Eclipse) I am trying to set up a delay in changing the text in a button. I am getting errors only after there is a delay and the text needs to be changed. Here is the simplified code without a while loop: final Button button_target = (Button) findViewById(R.id.button_target); Thread textChange = new Thread(new Runnable() { public void run(){ button_target.setText("fog"); try{ Thread.sleep(3000); }catch(InterruptedException e){} } }); textChange.start(); And now here is the code where a change of text on the button is required after the sleep which now causes and error and exit (forced): final Button button_target = (Button) findViewById(R.id.button_target); Thread textChange = new Thread(new Runnable() { public void run(){ button_target.setText("cat"); try{ Thread.sleep(3000); }catch(InterruptedException e){} button_target.setText("dog"); } }); textChange.start(); what am I doing to cause the error? Is there another method that I should do to be able to invoke a sleep or delay to the thread so that a text change operation can be performed? (the actual code has a while loop but I believe this form puts the error in highlight)

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• How to update GUI thread/class from worker thread/class?

  - by user315182

  First question here so hello everyone. The requirement I'm working on is a small test application that communicates with an external device over a serial port. The communication can take a long time, and the device can return all sorts of errors. The device is nicely abstracted in its own class that the GUI thread starts to run in its own thread and has the usual open/close/read data/write data basic functions. The GUI is also pretty simple - choose COM port, open, close, show data read or errors from device, allow modification and write back etc. The question is simply how to update the GUI from the device class? There are several distinct types of data the device deals with so I need a relatively generic bridge between the GUI form/thread class and the working device class/thread. In the GUI to device direction everything works fine with [Begin]Invoke calls for open/close/read/write etc. on various GUI generated events. I've read the thread here (How to update GUI from another thread in C#?) where the assumption is made that the GUI and worker thread are in the same class. Google searches throw up how to create a delegate or how to create the classic background worker but that's not at all what I need, although they may be part of the solution. So, is there a simple but generic structure that can be used? My level of C# is moderate and I've been programming all my working life, given a clue I'll figure it out (and post back)... Thanks in advance for any help.

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• Closing thread using ExitThread - C

  - by Jamie Keeling

  I have a simple program that creates a thread, loops twenty times and then makes a call to close itself and perform the necessary cleanup. When I debug the program it reaches the ExitThread(); method and pauses, ignoring the printf(); I have set up after it to signal to me it's closed. Is this normal or am I forgetting to do something? I'm new to threading using C. Main() void main() { Time t; int i = 0; StartTimer(); for(i = 0; i < 20; i++) { t = GetTime(); printf("%d.%.3d\n", t.seconds, t.milliseconds); Sleep(100); } StopTimer(); } Thread Creation void StartTimer() { DWORD threadId; seconds = 0; milliseconds = 0; // Create child thread hThread = CreateThread( NULL, // lpThreadAttributes (default) 0, // dwStackSize (default) ThreadFunc, // lpStartAddress NULL, // lpParameter 0, // dwCreationFlags &threadId // lpThreadId (returned by function) ); // Check child thread was created successfully if(hThread == NULL) { printf("Error creating thread\n"); } } Thread Close void StopTimer() { DWORD exitCode; if(GetExitCodeThread(hThread,&exitCode) != 0) { ExitThread(exitCode); printf("Thread closed"); if(CloseHandle(hThread)) { printf("Handle closed"); } } }

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