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  • Return Double from Boost thread

    - by Benedikt Wutzi
    Hi I have an Boost thread which should return a double. The function looks like this: void analyser::findup(const double startwl, const double max, double &myret){ this->data.begin(); for(int i = (int)data.size() ; i >= 0;i--){ if(this->data[i].lambda > startwl){ if(this->data[i].db >= (max-30)) { myret = this->data[i+1].lambda; std::cout <<"in thread " << myret << std::endl; return; } } } } this function is called by another function: void analyser::start_find_up(const double startwl, const double max){ double tmp = -42.0; boost::thread up(&analyser::findup,*this, startwl,max,tmp); std::cout << "before join " << tmp << std::endl; up.join(); std::cout << "after join " << tmp << std::endl; } Anyway I've tried and googled almost anything but i can't get it to return a value. The output looks like this right now. before join -42 in thread 843.487 after join -42 Thanks for any help.

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  • Thread-safety of read-only memory access

    - by Edmund
    I've implemented the Barnes-Hut gravity algorithm in C as follows: Build a tree of clustered stars. For each star, traverse the tree and apply the gravitational forces from each applicable node. Update the star velocities and positions. Stage 2 is the most expensive stage, and so is implemented in parallel by dividing the set of stars. E.g. with 1000 stars and 2 threads, I have one thread processing the first 500 stars and the second thread processing the second 500. In practice this works: it speeds the computation by about 30% with two threads on a two-core machine, compared to the non-threaded version. Additionally, it yields the same numerical results as the original non-threaded version. My concern is that the two threads are accessing the same resource (namely, the tree) simultaneously. I have not added any synchronisation to the thread workers, so it's likely they will attempt to read from the same location at some point. Although access to the tree is strictly read-only I am not 100% sure it's safe. It has worked when I've tested it but I know this is no guarantee of correctness! Questions Do I need to make a private copy of the tree for each thread? Even if it is safe, are there performance problems of accessing the same memory from multiple threads?

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  • Passing variables from a thread to another form using C#

    - by kirstom14
    Hi, I am trying to pass 2 variables from a thread, in the MainForm, to another form, but when doing so an error occurs. private void TrackingThread( ) { float targetX = 0; float targetY = 0; while ( true ) { camera1Acquired.WaitOne( ); camera2Acquired.WaitOne( ); lock ( this ) { // stop the thread if it was signaled if ( ( x1 == -1 ) && ( y1 == -1 ) && ( x2 == -1 ) && ( y2 == -1 ) ) { break; } // get middle point targetX = ( x1 + x2 ) / 2; targetY = ( y1 + y2 ) / 2; } if (directionForm != null) { directionForm.RunMotors(targetX, targetY); } } } In the form, directionForm, I am simply displaying the variables targetX and targetY. The code for the directionForm.RunMotors() is the following: public void RunMotors(float x, float y) { label1.Text = "X-ordinate " + x.ToString(); label2.Text = "Y-ordinate " + y.ToString(); } The error happen when I am trying to display the two variables: "InvalidOperationException was unhandled Cross-threading operation not valid: Control label1 accessed from a thread other than . the thread it was created on" What shall I do??? Thanks in advance

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  • Need a Java based interruptible timer thread

    - by LambeauLeap
    I have a Main Program which is running a script on the target device(smart phone) and in a while loop waiting for stdout messages. However in this particular case, some of the heartbeat messages on the stdout could be spaced almost 45secs to a 1minute apart. something like: stream = device.runProgram(RESTORE_LOGS, new String[] {}); stream.flush(); String line = stream.readLine(); while (line.compareTo("") != 0) { reporter.commentOnJob(jobId, line); line = stream.readLine(); } So, I want to be a able to start a new interruptible thread after reading line from stdout with a required a sleep window. Upon being able to read a new line, I want to be able to interrupt/stop(having trouble killing the process), handle the newline of stdout text and restart a process. And it the event I am not able to read a line within the timer window(say 45secs) I want to a way to get out of my while loop either. I already tried the thread.run, thread.interrupt approach. But having trouble killing and starting a new thread. Is this the best way out or am I missing something obvious?

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  • .NET List Thread-Safe Implementation Suggestion needed

    - by Bamboo
    .Net List class isn't thread safe. I hope to achieve the minimal lock needed and yet still fulfilling the requirement such that as for reading, phantom record is allowed, and for writing, they must be thread-safe so there won't be any lost updates. So I have something like public static List<string> list = new List<string>(); In Methods that have **List.Add**/**List.Remove** , I always lock to assure thread safety lock (lockHelper) { list.Add(obj); or list.Remove(obj); } In Methods that requires **List Reading** I don't care about phantom record so I go ahead to read without any locking. In this case. Return a bool by checking whether a string had been added. if (list.Count() != 0) { return list.Contains("some string") } All I did was locking write accesses, and allow read accesses to go through without any locking. Is my thread safety idea valid? I understand there is List size expansion. Will it be ok? My guess is that when a List is expanding, it may uses a temp. list. This is ok becasue the temp list size will always have a boundary, and .Net class is well implemented, ie. there shouldn't be any indexOutOfBound or circular reference problems when reading was caught in updates.

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  • .NET SerialPort DataReceived event thread interference with main thread

    - by Kiran
    I am writing a serial communication program using the SerialPort class in C# to interact with a strip machine connected via a RS232 cable. When i send the command to the machine it responds with some bytes depending on the command. Like when i send a "\D" command, i am expecting to download the machine program data of 180 bytes as a continous string. As per the machine's manual, it suggests as a best practice to send an unreognized characters like comma (,) character to make sure the machine is initialized before sending the first command in the cycle. My serial communication code is as follows: public class SerialHelper { SerialPort commPort = null; string currentReceived = string.Empty; string receivedStr = string.Empty; private bool CommInitialized() { try { commPort = new SerialPort(); commPort.PortName = "COM1"; if (!commPort.IsOpen) commPort.Open(); commPort.BaudRate = 9600; commPort.Parity = System.IO.Ports.Parity.None; commPort.StopBits = StopBits.One; commPort.DataBits = 8; commPort.RtsEnable = true; commPort.DtrEnable = true; commPort.DataReceived += new SerialDataReceivedEventHandler(commPort_DataReceived); return true; } catch (Exception ex) { return false; } } void commPort_DataReceived(object sender, SerialDataReceivedEventArgs e) { SerialPort currentPort = (SerialPort)sender; currentReceived = currentPort.ReadExisting(); receivedStr += currentReceived; } internal int CommIO(string outString, int outLen, ref string inBuffer, int inLen) { receivedStr = string.Empty; inBuffer = string.Empty; if (CommInitialized()) { commPort.Write(outString); } System.Threading.Thread.Sleep(1500); int i = 0; while ((receivedStr.Length < inLen) && i < 10) { System.Threading.Thread.Sleep(500); i += 1; } if (!string.IsNullOrEmpty(receivedStr)) { inBuffer = receivedStr; } commPort.Close(); return inBuffer.Length; } } I am calling this code from a windows form as follows: len = SerialHelperObj.CommIO(",",1,ref inBuffer, 4) len = SerialHelperObj.CommIO(",",1,ref inBuffer, 4) If(inBuffer == "!?*O") { len = SerialHelperObj.CommIO("\D",2,ref inBuffer, 180) } A valid return value from the serial port looks like this: \D00000010000000000010 550 3250 0000256000 and so on ... I am getting some thing like this: \D00000010D,, 000 550 D,, and so on... I feel that my comm calls are getting interferred with the one when i send commands. But i am trying to make sure the result of the comma command then initiating the actual command. but the received thread is inserting the bytes from the previous communication cycle. Can any one please shed some light into this...? I lost quite some hair just trying to get this work. I am not sure where i am doing wrong

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  • .NET Thread Pool - Unresponsive WinForms UI

    - by Goober
    Scenario I have a Windows Forms Application. Inside the main form there is a loop that iterates around 3000 times, Creating a new instance of a class on a new thread to perform some calculations. Bearing in mind that this setup uses a Thread Pool, the UI does stay responsive when there are only around 100 iterations of this loop (100 Assets to process). But as soon as this number begins to increase heavily, the UI locks up into eggtimer mode and the thus the log that is writing out to the listbox on the form becomes unreadable. Question Am I right in thinking that the best way around this is to use a Background Worker? And is the UI locking up because even though I'm using lots of different threads (for speed), the UI itself is not on its own separate thread? Suggested Implementations greatly appreciated.

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  • C# Win Forms Thread Pool - Unresponsive UI

    - by Goober
    Scenario I have a Windows Form Application. Inside the main form there is a loop that iterates around 3000 times, Creating a new instance of a class on a new thread to perform some calculations. Baring in mind that this setup uses a Thread Pool, the UI does stay responsive when there are only around 100 iterations of this loop (100 Assets to process). But as soon as this number begins to increase heavily, the UI locks up into eggtimer mode and the thus the log that is writing out to the listbox on the form becomes unreadable. Question Am I right in thinking that the best way around this is to use a Background Worker? And is the UI locking up because even though I'm using lots of different threads (for speed), the UI itself is not on its own separate thread? Suggested Implementations greatly appreciated.

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  • python urllib2 thread safety

    - by jldupont
    Is urllib2 thread safe? I find that using urllib2.urlopen sometimes results in the thread issuing the call to stop functioning. Yes I have used the timeout option to no avail. Is there a thread safe HTTP GET functionality I could use? NOTE: I am not interested in using Twisted to solve this problem. I have used Twisted in the past and I love it but this time I need a simpler solution. NOTE2: I also tried httplib with the same result (blocking).

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  • ASP.NET Asynchronous Tasks - Worker Thread Not Releasing?

    - by user296752
    I am having an issue with testing asynchronous tasks in ASP.NET & IIS7. From what I have read, the worker thread should be released back into the thread pool while the I/O thread performs the async work, allowing ASP.NET to server other incoming requests. But when I simulate heavy load on the web application by making 20 simultaneous requests to a page (async.aspx) that performs long running async tasks, I am unable to browse to some other normal aspx page until the requests are just about done. Am I misunderstanding or missing something here? I am running Vista Biz x64, VS2008 + IIS7. I have the Async attribute applied to the Page directive.

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  • System.WIndows.Application static members are thread safe?

    - by Lirik
    The Application static members are supposed to be thread safe: The public static (Shared in Visual Basic) members of this type are thread safe. In addition, the FindResource and TryFindResource methods and the Properties and Resources properties are thread safe.1 How much can we trust that statement in a multithreaded environment when calling static member methods of System.Windows.Application? Update: It's all in reference to this question: http://stackoverflow.com/questions/2463822/threading-errors-with-application-loadcomponent-key-already-exists/2463866#2463866 I never thought I'd see a real bug in the library, but this must be the day for me... that question seems to show a genuine bug. Usually it's "user error," but this doesn't seem to be the case.

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  • C# How to kill parent thread

    - by Royson
    A parent has several child threads. If user click on stop button the parent thread should be killed with all child threads. //calls a main thread mainThread = new Thread(new ThreadStart(startWorking)); mainThread.Start(); //////////////////////////////////////////////// startWorking() { ManualResetEventInstance = new ManualResetEvent(false); ThreadPool.SetMaxThreads(m_ThreadPoolLimit, m_ThreadPoolLimit); for(int i = 0; i < list.count ; i++) { ThreadData obj_ThreadData = new ThreadData(); obj_ThreadData.name = list[i]; m_ThreadCount++; //execute WaitCallback obj_waitCallBack = new WaitCallback(startParsing); ThreadPool.QueueUserWorkItem(obj_waitCallBack, obj_ThreadData); } ManualResetEventInstance.WaitOne(); } I want to kill mainThread.

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  • How to make a thread stay runnig in c#

    - by menachem
    Hello, I have a Windows Form Application (Form1) that allow the user to open another Forms (FormGraph). In order to open the FormGraph App I use a thread that open it. Here is the code that the thread is running: private void ThreadCreateCurvedGraph() { FormGraph myGraph = new FormGraph(); myGraph.CreateCurvedGraph(...); myGraph.Show(); } My problem is that myGraph closed right after it's open. 1) Does anyone know why this is happening and how to make myGraph stay open? 2) After the user closed myGraph, How do I terminate the thread? Many thanks!

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  • Can NSTask safely be used outside the main thread?

    - by neoneye
    Yesterday I read somewhere that NSTask isn't thread safe and that bothers me a lot, because I'm running a NSTask within a NSThread and is so far not experiencing any threading issues with it. My code is organized like this A: main thread -> B: worker thread -> C: worker task C: The worker task is a commandline program. B: The worker thread can start/stop the worker task and send it commands. A: The main thread can send commands to the worker thread. If NSTask is supposed to be used only within the main thread, then I'm considering moving the NSTask start/stop code to the main thread, just to prevent possible threading issues. Can NSTask be used outside the main thread? And if not then what may be the threading issues with NSTask?

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  • python iterators and thread-safety

    - by Igor
    I have a class which is being operated on by two functions. One function creates a list of widgets and writes it into the class: def updateWidgets(self): widgets = self.generateWidgetList() self.widgets = widgets the other function deals with the widgets in some way: def workOnWidgets(self): for widget in self.widgets: self.workOnWidget(widget) each of these functions runs in it's own thread. the question is, what happens if the updateWidgets() thread executes while the workOnWidgets() thread is running? I am assuming that the iterator created as part of the for...in loop will keep some kind of reference to the old self.widgets object? So I will finish iterating over the old list... but I'd love to know for sure.

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  • C++ this as thread parameter, variables unavailable

    - by brecht
    I have three classes: class Rtss_Generator { int mv_transfersize; } class Rtss_GenSine : Rtss_Generator class Rtss_GenSineRpm : Rtss_GenSine Rtss_GenSine creates a thread in his constructer, it is started immediatly and the threadfunction is off-course declared static, waiting for an event to start calculating. the problem: all the variables that are accessed through the gen-pointer are 0, but it does not fail. Also, this-address in the constructer and the gen-pointer-address in the thread are the same, so the pointer is ok. this code is created and compile in visual studio 6.0 service pack 2003 ORIGINAL CODE no thread Rtss_GenSine::getNextData() { //[CALCULATION] //mv_transferSize is accessible and has ALWAYS value 1600 which is ok } NEW CODE Rtss_GenSine::Rtss_GenSine() { createThread(NULL, threadFunction, (LPVOID) this,0,0); } Rtss_GenSine::getNextData() { SetEvent(startCalculating); WaitForSingleObject(stoppedCalculaing, INFINITE); } DWORD Rtss_GenSine::threadFunction(LPVOID pParam) { Rtss_GenSine* gen = (Rtss_GenSine*) pParam; while(runThread) { WaitForSingleObject(startCalculating, INFINITE); ResetEvent(startCalculating) //[CALCULATION] //gen->mv_transferSize ---> it does not fail, but is always zero //all variables accessed via the gen-pointer are 0 setEvent(stoppedCalculaing) } }

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  • Java: is Exception class thread-safe?

    - by Vilius Normantas
    As I understand, Java's Exception class is certainly not immutable (methods like initCause and setStackTrace give some clues about that). So is it at least thread-safe? Suppose one of my classes has a field like this: private final Exception myException; Can I safely expose this field to multiple threads? I'm not willing to discuss concrete cases where and why this situation could occur. My question is more about the principle: can I tell that a class which exposes field of Exception type is thread-safe? Another example: class CustomException extends Exception { ... } Is this class thread-safe?

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  • Howto access thread data outside a thread

    - by Quandary
    Question: I start the MS Text-to-speech engine in a thread, in order to avoid a crash on DLL_attach. It starts fine, and the text to speech engine gets initialized, but I can't access ISpVoice outside the thread. How can I access ISpVoice outside the thread ? It's a global variable after all... #include <windows.h> #include <sapi.h> #include "XPThreads.h" ISpVoice * pVoice = NULL; unsigned long init_engine_thread(void* param) { Sleep(5000); printf("lolthread\n"); //HRESULT hr = CoInitializeEx(NULL, COINIT_MULTITHREADED); HRESULT hr = CoInitialize(NULL); if(FAILED(hr) ) { MessageBox(NULL, TEXT("Failed To Initialize"), TEXT("Error"), 0); char buffer[2000] ; sprintf(buffer, "An error occured: 0x%08X.\n", hr); FILE * pFile = fopen ( "c:\\temp\\CoInitialize_dll.txt" , "w" ); fwrite (buffer , 1 , strlen(buffer) , pFile ); fclose (pFile); } else { printf("trying to create instance.\n"); //HRESULT hr = CoCreateInstance(CLSID_SpVoice, NULL, CLSCTX_ALL, IID_ISpVoice, (void **) &pVoice); //hr = CoCreateInstance(CLSID_SpVoice, NULL, CLSCTX_ALL, IID_ISpVoice, (void **) &pVoice); //HRESULT hr = CoCreateInstance(__uuidof(ISpVoice), NULL, CLSCTX_INPROC_SERVER, IID_ISpVoice, (void **) &pVoice); HRESULT hr = CoCreateInstance(__uuidof(SpVoice), NULL, CLSCTX_ALL, IID_ISpVoice, (void **) &pVoice); if( SUCCEEDED( hr ) ) { printf("Succeeded\n"); hr = pVoice->Speak(L"The text to speech engine has been successfully initialized.", 0, NULL); } else { printf("failed\n"); MessageBox(NULL, TEXT("Failed To Create COM instance"), TEXT("Error"), 0); char buffer[2000] ; sprintf(buffer, "An error occured: 0x%08X.\n", hr); FILE * pFile = fopen ( "c:\\temp\\CoCreateInstance_dll.txt" , "w" ); fwrite (buffer , 1 , strlen(buffer) , pFile ); fclose (pFile); } } if(pVoice != NULL) { pVoice->Release(); pVoice = NULL; } CoUninitialize(); return NULL; } XPThreads* ptrThread = new XPThreads(init_engine_thread); BOOL APIENTRY DllMain( HMODULE hModule, DWORD ul_reason_for_call, LPVOID lpReserved) { switch (ul_reason_for_call) { case DLL_PROCESS_ATTACH: //init_engine(); LoadLibrary(TEXT("ole32.dll")); ptrThread->Run(); break; case DLL_THREAD_ATTACH: break; case DLL_THREAD_DETACH: break; case DLL_PROCESS_DETACH: break; } return TRUE; }

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  • C++ Thread Safe Integer

    - by Paul Ridgway
    Hello everyone, I have currently created a C++ class for a thread safe integer which simply stores an integer privately and has public get a set functions which use a boost::mutex to ensure that only one change at a time can be applied to the integer. Is this the most efficient way to do it, I have been informed that mutexes are quite resource intensive? The class is used a lot, very rapidly so it could well be a bottleneck... Googleing C++ Thread Safe Integer returns unclear views and oppinions on the thread safety of integer operations on different architectures. Some say that a 32bit int on a 32bit arch is safe, but 64 on 32 isn't due to 'alignment' Others say it is compiler/OS specific (which I don't doubt). I am using Ubuntu 9.10 on 32 bit machines, some have dual cores and so threads may be executed simultaneously on different cores in some cases and I am using GCC 4.4's g++ compiler. Thanks in advance...

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  • Win32 Thread Exits Unexpectedly

    - by sahs
    Hello, I'm writing a C++ application. I realized that one of my worker threads may terminate unexpectedly. The (VS 2005) debug log says: The thread 'Win32 Thread' (0x5d98) has exited with code -858993460 (0xcccccccc). I surrounded all the worker thread code with a try/catch block. So, if the reason was an exception, I would catch it. But I can't: try{ ... Connection* conn = connectionPool->getConnection(); // unexpected exit occurs here ... } catch(exception& e) { ... } I have ten threads running concurrently, and only one of them gets crashed after some time, while the others continue running (and getting new [OCCI] connections). Is there an exception type that is not caught by "exception"? Or what do I not know about threads/exceptions? Thanks.

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  • Minimizing Java Thread Context Switching Overhead

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

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

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

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  • thread destructors in C++0x vs boost

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

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  • Thread help with Android game

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

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  • VC++ - Asynchronous Thread

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

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