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  • Singleton again, but with multi-thread and Objective-C

    - by Tonny Xu
    I know Singleton pattern has been discussed so much. But because I'm not fully understand the memory management mechanism in Objective-C, so when I combined Singleton implementation with multithreading, I got a big error and cost me a whole day to resolve it. I had a singleton object, let's call it ObjectX. I declared an object inside ObjectX that will detach a new thread, let's call that object objectWillSpawnNewThread, when I called [[ObjectX sharedInstance].objectWillSpawnNewThread startNewThread]; The new thread could not be executed correctly, and finally I found out that I should not declare the object objectWillSpawnNewThread inside the singleton class. Here are my questions: How does Objective-C allocate static object in the memory? Where does Objective-C allocate them(Main thread stack or somewhere else)? Why would it be failed if we spawn a new thread inside the singleton object? I had searched the Objective-C language [ObjC.pdf] and Objective-C memory management document, maybe I missed something, but I currently I could not find any helpful information.

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  • Is DataRow thread safe? How to update a single datarow in a datatable using multiple threads? - .net

    - by NLV
    Hello all I want to update a single datarow in a datatable using multiple threads. Is this actually possible? I've written the following code implementing a simple multi-threading to update a single datarow. I get different results each time. Why is it so? public partial class Form1 : Form { private static DataTable dtMain; private static string threadMsg = string.Empty; public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { Thread[] thArr = new Thread[5]; dtMain = new DataTable(); dtMain.Columns.Add("SNo"); DataRow dRow; dRow = dtMain.NewRow(); dRow["SNo"] = 5; dtMain.Rows.Add(dRow); dtMain.AcceptChanges(); ThreadStart ts = new ThreadStart(delegate { dtUpdate(); }); thArr[0] = new Thread(ts); thArr[1] = new Thread(ts); thArr[2] = new Thread(ts); thArr[3] = new Thread(ts); thArr[4] = new Thread(ts); thArr[0].Start(); thArr[1].Start(); thArr[2].Start(); thArr[3].Start(); thArr[4].Start(); while (!WaitTillAllThreadsStopped(thArr)) { Thread.Sleep(500); } foreach (Thread thread in thArr) { if (thread != null && thread.IsAlive) { thread.Abort(); } } dgvMain.DataSource = dtMain; } private void dtUpdate() { for (int i = 0; i < 1000; i++) { try { dtMain.Rows[0][0] = Convert.ToInt32(dtMain.Rows[0][0]) + 1; dtMain.AcceptChanges(); } catch { continue; } } } private bool WaitTillAllThreadsStopped(Thread[] threads) { foreach (Thread thread in threads) { if (thread != null && thread.ThreadState == ThreadState.Running) { return false; } } return true; } } Any thoughts on this? Thank you NLV

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  • Mac OS X Client With Static DHCP Assignment Requests Wrong IP via Option 50

    - by Starchy
    I have a number of Mac (and a few Linux) laptops getting DHCP from a Force10 layer 3 switch, the only DHCP server on the subnet. There's a global dynamic pool, and for each full-time employee's laptop I have a single IP static pool set by MAC address. One and only one of the clients, running OS X 10.7.5, consistently fails to get a static assignment. The MAC address in the static pool definition has been carefully re-checked. Running tcpdump on a mirrored port when the laptop connects, I see that it is specifically requesting 10.100.0.252 (a dynamic address): 11:32:10.108280 IP (tos 0x0, ttl 255, id 28293, offset 0, flags [none], proto UDP (17), length 328) 0.0.0.0.bootpc > broadcasthost.bootps: [udp sum ok] BOOTP/DHCP, Request from 3c:07:54:xx:xx:xx (oui Unknown), length 300, xid 0x1399da89, Flags [none] (0x0000) Client-Ethernet-Address 3c:07:54:xx:xx:xx (oui Unknown) Vendor-rfc1048 Extensions Magic Cookie 0x63825363 DHCP-Message Option 53, length 1: Request Parameter-Request Option 55, length 9: Subnet-Mask, Default-Gateway, Domain-Name-Server, Domain-Name Option 119, LDAP, Option 252, Netbios-Name-Server Netbios-Node MSZ Option 57, length 2: 1500 Client-ID Option 61, length 7: ether 3c:07:54:xx:xx:xx Requested-IP Option 50, length 4: 10.100.0.252 Lease-Time Option 51, length 4: 7776000 Hostname Option 12, length 10: "host-name" END Option 255, length 0 PAD Option 0, length 0, occurs 8 I haven't been able to find any extra system prefs or unusual software on the laptop. Disabling the interface and rebooting or temporarily setting the IP manually both fail to make any difference. Any suggestions appreciated.

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  • Query on simple C++ threadpool implementation

    - by ticketman
    Stackoverflow has been a tremendous help to me and I'd to give something back to the community. I have been implementing a simple threadpool using the tinythread C++ portable thread library, using what I have learnt from Stackoverflow. I am new to thread programming, so not that comfortable with mutexes, etc. I have a question best asked after presenting the code (which runs quite well under Linux): // ThreadPool.h class ThreadPool { public: ThreadPool(); ~ThreadPool(); // Creates a pool of threads and gets them ready to be used void CreateThreads(int numOfThreads); // Assigns a job to a thread in the pool, but doesn't start the job // Each SubmitJob call will use up one thread of the pool. // This operation can only be undone by calling StartJobs and // then waiting for the jobs to complete. On completion, // new jobs may be submitted. void SubmitJob( void (*workFunc)(void *), void *workData ); // Begins execution of all the jobs in the pool. void StartJobs(); // Waits until all jobs have completed. // The wait will block the caller. // On completion, new jobs may be submitted. void WaitForJobsToComplete(); private: enum typeOfWorkEnum { e_work, e_quit }; class ThreadData { public: bool ready; // thread has been created and is ready for work bool haveWorkToDo; typeOfWorkEnum typeOfWork; // Pointer to the work function each thread has to call. void (*workFunc)(void *); // Pointer to work data void *workData; ThreadData() : ready(false), haveWorkToDo(false) { }; }; struct ThreadArgStruct { ThreadPool *threadPoolInstance; int threadId; }; // Data for each thread ThreadData *m_ThreadData; ThreadPool(ThreadPool const&); // copy ctor hidden ThreadPool& operator=(ThreadPool const&); // assign op. hidden // Static function that provides the function pointer that a thread can call // By including the ThreadPool instance in the void * parameter, // we can use it to access other data and methods in the ThreadPool instance. static void ThreadFuncWrapper(void *arg) { ThreadArgStruct *threadArg = static_cast<ThreadArgStruct *>(arg); threadArg->threadPoolInstance->ThreadFunc(threadArg->threadId); } // The function each thread calls void ThreadFunc( int threadId ); // Called by the thread pool destructor void DestroyThreadPool(); // Total number of threads available // (fixed on creation of thread pool) int m_numOfThreads; int m_NumOfThreadsDoingWork; int m_NumOfThreadsGivenJobs; // List of threads std::vector<tthread::thread *> m_ThreadList; // Condition variable to signal each thread has been created and executing tthread::mutex m_ThreadReady_mutex; tthread::condition_variable m_ThreadReady_condvar; // Condition variable to signal each thread to start work tthread::mutex m_WorkToDo_mutex; tthread::condition_variable m_WorkToDo_condvar; // Condition variable to signal the main thread that // all threads in the pool have completed their work tthread::mutex m_WorkCompleted_mutex; tthread::condition_variable m_WorkCompleted_condvar; }; cpp file: // // ThreadPool.cpp // #include "ThreadPool.h" // This is the thread function for each thread. // All threads remain in this function until // they are asked to quit, which only happens // when terminating the thread pool. void ThreadPool::ThreadFunc( int threadId ) { ThreadData *myThreadData = &m_ThreadData[threadId]; std::cout << "Hello world: Thread " << threadId << std::endl; // Signal that this thread is ready m_ThreadReady_mutex.lock(); myThreadData->ready = true; m_ThreadReady_condvar.notify_one(); // notify the main thread m_ThreadReady_mutex.unlock(); while(true) { //tthread::lock_guard<tthread::mutex> guard(m); m_WorkToDo_mutex.lock(); while(!myThreadData->haveWorkToDo) // check for work to do m_WorkToDo_condvar.wait(m_WorkToDo_mutex); // if no work, wait here myThreadData->haveWorkToDo = false; // need to do this before unlocking the mutex m_WorkToDo_mutex.unlock(); // Do the work switch(myThreadData->typeOfWork) { case e_work: std::cout << "Thread " << threadId << ": Woken with work to do\n"; // Do work myThreadData->workFunc(myThreadData->workData); std::cout << "#Thread " << threadId << ": Work is completed\n"; break; case e_quit: std::cout << "Thread " << threadId << ": Asked to quit\n"; return; // ends the thread } // Now to signal the main thread that my work is completed m_WorkCompleted_mutex.lock(); m_NumOfThreadsDoingWork--; // Unsure if this 'if' would make the program more efficient // if(NumOfThreadsDoingWork == 0) m_WorkCompleted_condvar.notify_one(); // notify the main thread m_WorkCompleted_mutex.unlock(); } } ThreadPool::ThreadPool() { m_numOfThreads = 0; m_NumOfThreadsDoingWork = 0; m_NumOfThreadsGivenJobs = 0; } ThreadPool::~ThreadPool() { if(m_numOfThreads) { DestroyThreadPool(); delete [] m_ThreadData; } } void ThreadPool::CreateThreads(int numOfThreads) { // Check a thread pool has already been created if(m_numOfThreads > 0) return; m_NumOfThreadsGivenJobs = 0; m_NumOfThreadsDoingWork = 0; m_numOfThreads = numOfThreads; m_ThreadData = new ThreadData[m_numOfThreads]; ThreadArgStruct threadArg; for(int i=0; i<m_numOfThreads; ++i) { threadArg.threadId = i; threadArg.threadPoolInstance = this; // Creates the thread and save in a list so we can destroy it later m_ThreadList.push_back( new tthread::thread( ThreadFuncWrapper, (void *)&threadArg ) ); // It takes a little time for a thread to get established. // Best wait until it gets established before creating the next thread. m_ThreadReady_mutex.lock(); while(!m_ThreadData[i].ready) // Check if thread is ready m_ThreadReady_condvar.wait(m_ThreadReady_mutex); // If not, wait here m_ThreadReady_mutex.unlock(); } } // Adds a job to the batch, but doesn't start the job void ThreadPool::SubmitJob(void (*workFunc)(void *), void *workData) { // Check that the thread pool has been created if(!m_numOfThreads) return; if(m_NumOfThreadsGivenJobs >= m_numOfThreads) return; m_ThreadData[m_NumOfThreadsGivenJobs].workFunc = workFunc; m_ThreadData[m_NumOfThreadsGivenJobs].workData = workData; std::cout << "Submitted job " << m_NumOfThreadsGivenJobs << std::endl; m_NumOfThreadsGivenJobs++; } void ThreadPool::StartJobs() { // Check that the thread pool has been created // and some jobs have been assigned if(!m_numOfThreads || !m_NumOfThreadsGivenJobs) return; // Set 'haveworkToDo' flag for all threads m_WorkToDo_mutex.lock(); for(int i=0; i<m_NumOfThreadsGivenJobs; ++i) m_ThreadData[i].haveWorkToDo = true; m_NumOfThreadsDoingWork = m_NumOfThreadsGivenJobs; // Reset this counter so we can resubmit jobs later m_NumOfThreadsGivenJobs = 0; // Notify all threads they have work to do m_WorkToDo_condvar.notify_all(); m_WorkToDo_mutex.unlock(); } void ThreadPool::WaitForJobsToComplete() { // Check that a thread pool has been created if(!m_numOfThreads) return; m_WorkCompleted_mutex.lock(); while(m_NumOfThreadsDoingWork > 0) // Check if all threads have completed their work m_WorkCompleted_condvar.wait(m_WorkCompleted_mutex); // If not, wait here m_WorkCompleted_mutex.unlock(); } void ThreadPool::DestroyThreadPool() { std::cout << "Ask threads to quit\n"; m_WorkToDo_mutex.lock(); for(int i=0; i<m_numOfThreads; ++i) { m_ThreadData[i].haveWorkToDo = true; m_ThreadData[i].typeOfWork = e_quit; } m_WorkToDo_condvar.notify_all(); m_WorkToDo_mutex.unlock(); // As each thread terminates, catch them here for(int i=0; i<m_numOfThreads; ++i) { tthread::thread *t = m_ThreadList[i]; // Wait for thread to complete t->join(); } m_numOfThreads = 0; } Example of usage: (this calculates pi-squared/6) struct CalculationDataStruct { int inputVal; double outputVal; }; void LongCalculation( void *theSums ) { CalculationDataStruct *sums = (CalculationDataStruct *)theSums; int terms = sums->inputVal; double sum; for(int i=1; i<terms; i++) sum += 1.0/( double(i)*double(i) ); sums->outputVal = sum; } int main(int argc, char** argv) { int numThreads = 10; // Create pool ThreadPool threadPool; threadPool.CreateThreads(numThreads); // Create thread workspace CalculationDataStruct sums[numThreads]; // Set up jobs for(int i=0; i<numThreads; i++) { sums[i].inputVal = 3000*(i+1); threadPool.SubmitJob(LongCalculation, &sums[i]); } // Run the jobs threadPool.StartJobs(); threadPool.WaitForJobsToComplete(); // Print results for(int i=0; i<numThreads; i++) std::cout << "Sum of " << sums[i].inputVal << " terms is " << sums[i].outputVal << std::endl; return 0; } Question: In the ThreadPool::ThreadFunc method, would better performance be obtained if the following if statement if(NumOfThreadsDoingWork == 0) was included? Also, I'd be grateful of criticisms and ways to improve the code. At the same time, I hope the code is of use to others.

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  • Public static ip for vagrant box

    - by Numbata
    I have server (Debian Squeeze) with 1 ethernet card and 2 public static IPs (188.120.245.4 and 188.120.244.5). What I want: Setup virtual box (Ubuntu) with access via static IP (188.120.244.5). What I was trying: config.vm.forward_port - good idea: setup interface "eth1:1" with 188.120.244.5 on host-machine, and add to Vagrant file "config.vm.forward_port = hmm..?" config.vm.network :hostonly, "188.120.244.5" - not working. Was created new interface on host-machine with ip "188.120.244.1". Of course 188.120.244.1 IP isn't mine and I can't access my server via this IP. config.vm.network :bridged - I'm confused how this works :) What I have now: Not working configuration. Debian-host-machine# cat Vagrantfile Vagrant::Config.run do |config| config.vm.define :gitlab do |box_config| box_config.vm.box = "ubuntu" box_config.vm.host_name = "ubuntu" box_config.vm.network :bridged box_config.vm.network :hostonly, "188.120.244.5", :auto_config => false end end Debian-host-machine# ifconfig eth1 Link encap:Ethernet HWaddr 00:15:17:69:71:bb inet addr:188.120.245.4 Bcast:188.120.247.255 Mask:255.255.248.0 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 vboxnet0 Link encap:Ethernet HWaddr 0a:00:27:00:00:00 inet addr:188.120.244.1 Bcast:188.120.246.255 Mask:255.255.255.0 Ubuntu-virtual-machine# ifconfig eth0 Link encap:Ethernet HWaddr 08:00:27:ee:8d:0c inet addr:10.0.2.15 Bcast:10.0.2.255 Mask:255.255.255.0 eth1 Link encap:Ethernet HWaddr 08:00:27:45:71:87 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 How I can access virtual box via public static IP from network? I'm using Oracle VM VirtualBox Manager 4.1.18 and Vagrant version 1.0.3. Thanks in advance for your feedback.

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  • How thread-safe is enum in java?

    - by portoalet
    Hi, How thread-safe is enum in java? I am implementing a Singleton using enum (as per Bloch's Effective Java), should I worry at all about thread safety for my singleton enum? Is there a way to prove or disprove that it is thread safe? // Enum singleton - the preferred approach public enum Elvis { INSTANCE; public void leaveTheBuilding() { ... } } Thanks

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  • How to handle data output in an Observer?

    - by Mannaz
    I have an Observable and an Observer. The observable does download some stuff in a background thread and calls notifyObservers to let the observers read the status. At some point in public void update the observer tries to updates the GUI ((TextView)findViewById('R.id.foo')).setText("bar"); but it seems like the observable thread calls this method, because the Observable (!!!) throws this: android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views. at android.view.ViewRoot.checkThread(ViewRoot.java:2462) at android.view.ViewRoot.requestLayout(ViewRoot.java:512) ... at com.mynamespace.acitivty.TrackActivity.startPlay(TrackActivity.java:72) at com.mynamespace.acitivty.TrackActivity.update(TrackActivity.java:107) at java.util.Observable.notifyObservers(Observable.java:147) at java.util.Observable.notifyObservers(Observable.java:128) at com.mynamespace.module.communication.Download.stateChanged(Download.java:213) at com.mynamespace.module.communication.Download.run(Download.java:186) at java.lang.Thread.run(Thread.java:1058) Is there some way I can prevent this from happening? I'm sure I'm missing something obvious here.

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  • how to generate thread dump java on out of memory error

    - by Jigar
    does java 6 generate thread dump in addition to heap dump (java_pid14941.hprof) this is what happened to one of my applications. java.lang.OutOfMemoryError: GC overhead limit exceeded Dumping heap to java_pid14941.hprof ... I did find ava_pid14941.hprof in working directory, but didn't find any file which contains thread dump. I need to know what all the threads were doing when I got this OutOfMemory error. Is there any configuration option which will generate thread dump in addition to heap dump on out of memory exception?

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  • No internet access when using static IP

    - by Endy Tjahjono
    I have just upgraded to Windows 8.1, and after the upgrade process is finished, I can't connect to internet. I tried running the "Troubleshoot problems": It concluded that DHCP needs to be activated: I let it activate DHCP, and I got internet connection back. The problem is I want to set this PC to a certain IP address (the IP address that it has been using all this time). I am also using Hyper-V, which I suspect has something to do with this problem. After I regained internet connection, I tried running one of my Hyper-V VM. From inside the VM I can connect to internet. That VM has static IP address. I also noticed that in "Control Panel\Network and Internet\Network Connections", I usually have a network connection called vEthernet (Realtek PCIe GBE Family Controller Virtual Switch). I didn't find it there after upgrade. How do I set my PC to a static IP while retaining internet access in Windows 8.1? EDIT I have managed to recreate vEthernet (Realtek PCIe GBE Family Controller Virtual Switch) by unchecking Allow management operating system to share this network adapter in Hyper-V's Virtual Switch Manager and then checking it again. But when I changed the adapter to use static IP, it still can't connect to internet. Result of Get-NetAdapter -Name * | fl (with MAC address removed): Name : vEthernet (Realtek PCIe GBE Family Controller Virtual Switch) InterfaceDescription : Hyper-V Virtual Ethernet Adapter #2 InterfaceIndex : 5 MacAddress : 55-55-55-55-55-55 MediaType : 802.3 PhysicalMediaType : Unspecified InterfaceOperationalStatus : Up AdminStatus : Up LinkSpeed(Mbps) : 100 MediaConnectionState : Connected ConnectorPresent : False DriverInformation : Driver Date 2006-06-21 Version 6.3.9600.16384 NDIS 6.40 Name : Ethernet 3 InterfaceDescription : Hyper-V Virtual Ethernet Adapter #3 InterfaceIndex : 6 MacAddress : 55-55-55-55-55-56 MediaType : 802.3 PhysicalMediaType : Unspecified InterfaceOperationalStatus : Up AdminStatus : Up LinkSpeed(Gbps) : 10 MediaConnectionState : Connected ConnectorPresent : False DriverInformation : Driver Date 2006-06-21 Version 6.3.9600.16384 NDIS 6.40 Name : Ethernet InterfaceDescription : Realtek PCIe GBE Family Controller InterfaceIndex : 2 MacAddress : 55-55-55-55-55-57 MediaType : 802.3 PhysicalMediaType : 802.3 InterfaceOperationalStatus : Up AdminStatus : Up LinkSpeed(Mbps) : 100 MediaConnectionState : Connected ConnectorPresent : True DriverInformation : Driver Date 2013-05-10 Version 8.1.510.2013 NDIS 6.30

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  • Setting thread culture to default

    - by synergetic
    In silverlight application I have MyTexts.resx (for english) and MyTexts.ja-JP.resx (for japanese) resource files. Before loading a page I can set current culture to japanese as following: Thread.CurrentThread.CurrentCulture = new CultureInfo("ja-JP"); Thread.CurrentThread.CurrentUICulture = new CultureInfo("ja-JP"); But sometimes I need to reset culture to default. How can I do that? The following wouldn't work: Thread.CurrentThread.CurrentCulture = new CultureInfo("default"); OR Thread.CurrentThread.CurrentCulture = new CultureInfo("en-US");

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  • How to open AsyncTask from a Thread

    - by Abhishek
    In my application I have created a SplashScreen that will b shown for 5 Seconds and after that it executes an if else case depending upon the values stored in the Preference file. If Preference file contains values then the AsyncTask code will run else the Login form will load. When i try to run my application. The thread is going to the Login form with the help of intent but when it comes to AsyncTask my application shows a force close error message. This is my SplashScreen code: public class SplashScreen extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.splashscreen); Thread timer = new Thread() { public void run() { try { sleep(5000); } catch(InterruptedException e) { e.printStackTrace(); } finally { if(GoGolfPref.getEmail(SplashScreen.this)!=null && GoGolfPref.getPass(SplashScreen.this)!=null) { new LoadingScreen(SplashScreen.this, SplashScreen.this).execute("login_page", Login.url+GoGolfPref.getEmail(SplashScreen.this)+"/"+GoGolfPref.getPass(SplashScreen.this)); } else { Intent in = new Intent(SplashScreen.this, Login.class); startActivity(in); finish(); } } } }; timer.start(); } } This is the error I am getting: 08-29 07:25:58.040: E/AndroidRuntime(2365): FATAL EXCEPTION: Thread-10 08-29 07:25:58.040: E/AndroidRuntime(2365): java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare() 08-29 07:25:58.040: E/AndroidRuntime(2365): at android.os.Handler.<init>(Handler.java:121) 08-29 07:25:58.040: E/AndroidRuntime(2365): at android.app.Dialog.<init>(Dialog.java:101) 08-29 07:25:58.040: E/AndroidRuntime(2365): at android.app.AlertDialog.<init>(AlertDialog.java:63) 08-29 07:25:58.040: E/AndroidRuntime(2365): at android.app.ProgressDialog.<init>(ProgressDialog.java:80) 08-29 07:25:58.040: E/AndroidRuntime(2365): at android.app.ProgressDialog.<init>(ProgressDialog.java:76) 08-29 07:25:58.040: E/AndroidRuntime(2365): at com.pnf.gogolf.LoadingScreen.<init>(LoadingScreen.java:130) 08-29 07:25:58.040: E/AndroidRuntime(2365): at com.pnf.gogolf.SplashScreen$1.run(SplashScreen.java:32) How to get this working? Thanks in advance...

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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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  • create a list of threads in C

    - by Hristo
    My implementation (in C) isn't working... the first node is always NULL so I can't free the memory. I'm doing: thread_node_t *thread_list_head = NULL; // done in the beginning of the program ... // later on in the program thread_node_t *thread = (thread_node_t*) malloc(sizeof(thread_node_t)); pthread_create(&(thread->thread), NULL, client_thread, &csFD); thread->next = thread_list_head; thread_list_head = thread; So when I try to free this memory, thread_list_head is NULL. while (thread_list_head != NULL) { thread_node_t *temp = thread_list_head; thread_list_head = thread_list_head->next; free(temp); temp = NULL; } Any advice on how to fix this or just a new way to create this list that would work better? Thanks, Hristo

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  • How to associate static entity instances in a Session without database retrieval

    - by Michael Hedgpeth
    I have a simple Result class that used to be an Enum but has evolved into being its own class with its own table. public class Result { public static readonly Result Passed = new Result(StatusType.Passed) { Id = [Predefined] }; public static readonly Result NotRun = new Result(StatusType.NotRun) { Id = [Predefined] }; public static readonly Result Running = new Result(StatusType.Running) { Id = [Predefined] }; } Each of these predefined values has a row in the database at their predefined Guid Id. There is then a failed result that has an instance per failure: public class FailedResult : Result { public FailedResult(string description) : base(StatusType.Failed) { . . . } } I then have an entity that has a Result: public class Task { public Result Result { get; set; } } When I save a Task, if the Result is a predefined one, I want NHibernate to know that it doesn't need to save that to the database, nor does it need to fetch it from the database; I just want it to save by Id. The way I get around this is when I am setting up the session, I call a method to load the static entities: protected override void OnSessionOpened(ISession session) { LockStaticResults(session, Result.Passed, Result.NotRun, Result.Running); } private static void LockStaticResults(ISession session, params Result[] results) { foreach (var result in results) { session.Load(result, result.Id); } } The problem with the session.Load method call is it appears to be fetching to the database (something I don't want to do). How could I make this so it does not fetch the database, but trusts that my static (immutable) Result instances are both up to date and a part of the session?

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  • Thread safe lazy contruction of a singleton in C++

    - by pauldoo
    Is there a way to implement a singleton object in C++ that is: Lazily constructed in a thread safe manner (two threads might simultaneously be the first user of the singleton - it should still only be constructed once). Doesn't rely on static variables being constructed beforehand (so the singleton object is itself safe to use during the construction of static variables). (I don't know my C++ well enough, but is it the case that integral and constant static variables are initialized before any code is executed (ie, even before static constructors are executed - their values may already be "initialized" in the program image)? If so - perhaps this can be exploited to implement a singleton mutex - which can in turn be used to guard the creation of the real singleton..) Excellent, it seems that I have a couple of good answers now (shame I can't mark 2 or 3 as being the answer). There appears to be two broad solutions: Use static initialisation (as opposed to dynamic initialisation) of a POD static varible, and implementing my own mutex with that using the builtin atomic instructions. This was the type of solution I was hinting at in my question, and I believe I knew already. Use some other library function like pthread_once or boost::call_once. These I certainly didn't know about - and am very grateful for the answers posted.

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  • Why Eventmachine Defer slower than Ruby Thread?

    - by allenwei
    I have two scripts which using mechanize to fetch google index page. I assuming Eventmachine will faster than ruby thread, but not. Eventmachine code cost "0.24s user 0.08s system 2% cpu 12.682 total" Ruby Thread code cost "0.22s user 0.08s system 5% cpu 5.167 total " Am I use eventmachine in wrong way? Who can explain it to me, thanks! 1 Eventmachine require 'rubygems' require 'mechanize' require 'eventmachine' trap("INT") {EM.stop} EM.run do num = 0 operation = proc { agent = Mechanize.new sleep 1 agent.get("http://google.com").body.to_s.size } callback = proc { |result| sleep 1 puts result num+=1 EM.stop if num == 9 } 10.times do EventMachine.defer operation, callback end end 2 Ruby Thread require 'rubygems' require 'mechanize' threads = [] 10.times do threads << Thread.new do agent = Mechanize.new sleep 1 puts agent.get("http://google.com").body.to_s.size sleep 1 end end threads.each do |aThread| aThread.join end

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  • Will thread.join() block other clients also?

    - by maxp
    In an asp.net web application, say everytime the user makes the request, and the page loads, a thread is fired off that uses thread.join() to block execution until it's finished. Say this thread takes 10 seconds to complete. Does this mean that if 5 totally seperate users make a request to this page, mere miliseconds after the last, does this mean the last user is going to wait 50 seconds to finish their request? Or is each client request threaded?

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  • Synchronizing thread communication?

    - by Roger Alsing
    Just for the heck of it I'm trying to emulate how JRuby generators work using threads in C#. Also, I'm fully aware that C# haas built in support for yield return, I'm just toying around a bit. I guess it's some sort of poor mans coroutines by keeping multiple callstacks alive using threads. (even though none of the callstacks should execute at the same time) The idea is like this: The consumer thread requests a value The worker thread provides a value and yields back to the consumer thread Repeat untill worker thread is done So, what would be the correct way of doing the following? //example class Program { static void Main(string[] args) { ThreadedEnumerator<string> enumerator = new ThreadedEnumerator<string>(); enumerator.Init(() => { for (int i = 1; i < 100; i++) { enumerator.Yield(i.ToString()); } }); foreach (var item in enumerator) { Console.WriteLine(item); }; Console.ReadLine(); } } //naive threaded enumerator public class ThreadedEnumerator<T> : IEnumerator<T>, IEnumerable<T> { private Thread enumeratorThread; private T current; private bool hasMore = true; private bool isStarted = false; AutoResetEvent enumeratorEvent = new AutoResetEvent(false); AutoResetEvent consumerEvent = new AutoResetEvent(false); public void Yield(T item) { //wait for consumer to request a value consumerEvent.WaitOne(); //assign the value current = item; //signal that we have yielded the requested enumeratorEvent.Set(); } public void Init(Action userAction) { Action WrappedAction = () => { userAction(); consumerEvent.WaitOne(); enumeratorEvent.Set(); hasMore = false; }; ThreadStart ts = new ThreadStart(WrappedAction); enumeratorThread = new Thread(ts); enumeratorThread.IsBackground = true; isStarted = false; } public T Current { get { return current; } } public void Dispose() { enumeratorThread.Abort(); } object System.Collections.IEnumerator.Current { get { return Current; } } public bool MoveNext() { if (!isStarted) { isStarted = true; enumeratorThread.Start(); } //signal that we are ready to receive a value consumerEvent.Set(); //wait for the enumerator to yield enumeratorEvent.WaitOne(); return hasMore; } public void Reset() { throw new NotImplementedException(); } public IEnumerator<T> GetEnumerator() { return this; } System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { return this; } } Ideas?

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  • How to estimate the thread context switching overhead?

    - by Ignas Limanauskas
    I am trying to improve the performance of the threaded application with real-time deadlines. It is running on Windows Mobile and written in C / C++. I have a suspicion that high frequency of thread switching might be causing tangible overhead, but can neither prove it or disprove it. As everybody knows, lack of proof is not a proof of opposite :). Thus my question is twofold: If exists at all, where can I find any actual measurements of the cost of switching thread context? Without spending time writing a test application, what are the ways to estimate the thread switching overhead in the existing application? Does anyone know a way to find out the number of context switches (on / off) for a given thread?

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  • C functions invoked as threads - Linux userland program

    - by Einar
    I'm writing a linux daemon in C which gets values from an ADC by SPI interface (ioctl). The SPI (spidev - userland) seems to be a bit unstable and freezes the daemon at random times. I need to have some better control of the calls to the functions getting the values, and I was thinking of making it as a thread which I could wait for to finish and get the return value and if it times out assume that it froze and kill it without this new thread taking down the daemon itself. Also I could do other things like resetting the ADC before restarting. Is this possible? Pseudo example of what I want to achieve: (function int get_adc_value(int adc_channel, float *value) ) pid = thread( get_adc_value(1,&value); //makes thread wait_until_finish(pid, timeout); //waits until function finishes/timesout if(timeout) kill pid, start over //if thread do not return in given time, kill it (it is frozen) else if return value sane, continue //if successful, handle return variable value and continue Thanks for any input on the matter, examples highly appreciated!

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  • Python - Subprocess Popen and Thread error

    - by n0idea
    In both functions record and ftp, i have subprocess.Popen if __name__ == '__main__': try: t1 = threading.Thread(target = record) t1.daemon = True t1.start() t2 = threading.Thread(target = ftp) t2.daemon = True t2.start() except (KeyboardInterrupt, SystemExit): sys.exit() The error I'm receiving is: Exception in thread Thread-1 (most likely raised during interpreter shutdown): Traceback (most recent call last): File "/usr/lib/python2.7/threading.py", line 551, in __bootstrap_inner File "/usr/lib/python2.7/threading.py", line 504, in run File "./in.py", line 20, in recordaudio File "/usr/lib/python2.7/subprocess.py", line 493, in call File "/usr/lib/python2.7/subprocess.py", line 679, in __init__ File "/usr/lib/python2.7/subprocess.py", line 1237, in _execute_child <type 'exceptions.AttributeError'>: 'NoneType' object has no attribute 'close' What might the issue be ?

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  • mongodb : Can create new thread on FreeBSD?

    - by user197739
    We experienced some strange thing in our mongodb gridfs platform. The platform actually is a bi Xeon E5 (bi quad core) with 128GB of memory, running on freebsd 9 with a zfs pool dedicated for mongodb. [root@mongofile1 ~]# uname -sr FreeBSD 9.1-RELEASE our /boot/loader.conf vfs.zfs.arc_min="2048M" vfs.zfs.arc_max="7680M" vm.kmem_size_max="16G" vm.kmem_size="12G" vfs.zfs.prefetch_disable="1" kern.ipc.nmbclusters="32768" /etc/sysctl.conf net.inet.tcp.msl=15000 net.inet.tcp.keepidle=300000 kern.ipc.nmbclusters=32768 kern.ipc.maxsockbuf=2097152 kern.ipc.somaxconn=8192 kern.maxfiles=65536 kern.maxfilesperproc=32768 net.inet.tcp.delayed_ack=0 net.inet.tcp.sendspace=65535 net.inet.udp.recvspace=65535 net.inet.udp.maxdgram=57344 net.local.stream.recvspace=65535 net.local.stream.sendspace=65535 we follow the recommendation for the ulimit : [root@mongofile1 ~]# su - mongodb $ ulimit -a cpu time (seconds, -t) unlimited file size (512-blocks, -f) unlimited data seg size (kbytes, -d) 33554432 stack size (kbytes, -s) 524288 core file size (512-blocks, -c) unlimited max memory size (kbytes, -m) unlimited locked memory (kbytes, -l) unlimited max user processes (-u) 5547 open files (-n) 32768 virtual mem size (kbytes, -v) unlimited swap limit (kbytes, -w) unlimited sbsize (bytes, -b) unlimited pseudo-terminals (-p) unlimited This server have a twin (same config exactly) for ReplSet in other data center and we have a virtualized arbiter. Some time, almost 3 days, the process of mongodb exit. The problem begin with: Fri Nov 8 11:27:31.741 [conn774697] end connection 192.168.10.162:47963 (23 connections now open) Fri Nov 8 11:27:31.770 [initandlisten] can't create new thread, closing connection Fri Nov 8 11:27:31.771 [rsHealthPoll] replSet member mongofile2:27017 is now in state DOWN Fri Nov 8 11:27:31.774 [initandlisten] connection accepted from 192.168.10.162:47968 #774702 (20 connections now open) Fri Nov 8 11:27:31.774 [initandlisten] connection accepted from 192.168.10.161:28522 #774703 (21 connections now open) Fri Nov 8 11:27:31.774 [initandlisten] connection accepted from 192.168.10.164:15406 #774704 (22 connections now open) Fri Nov 8 11:27:31.774 [initandlisten] connection accepted from 192.168.10.163:25750 #774705 (23 connections now open) Fri Nov 8 11:27:31.810 [initandlisten] connection accepted from 192.168.10.182:20779 #774706 (24 connections now open) Fri Nov 8 11:27:31.855 [initandlisten] connection accepted from 192.168.10.161:28524 #774707 (25 connections now open) Fri Nov 8 11:27:31.869 [initandlisten] connection accepted from 192.168.10.182:20786 #774708 (26 connections now open) and after many "can create new thread" [root@mongofile1 /usr/mongodb]# tail -n 15000 mongod.log.old |grep "create new thread"|wc 5020 55220 421680 and finish by a magnificent Fri Nov 8 11:30:22.333 [rsMgr] replSet warning caught unexpected exception in electSelf() pure virtual method called Fri Nov 8 11:30:22.333 Got signal: 6 (Abort trap: 6). Fri Nov 8 11:30:22.337 Backtrace: 0x599efc 0x8035cb516 0x599efc <_ZN5mongo10abruptQuitEi+988> at /usr/local/bin/mongod 0x8035cb516 <_pthread_sigmask+918> at /lib/libthr.so.3 Extract of mongodb from top 78126 mongodb 77 20 0 1253G 1449M sbwait 0 0:20 0.00% mongod If I restart the process when it crash, the problem is fixed for almost 3 days. Has anyone seen this before, or know of a fix?

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  • ThreadPool.QueueUserWorkItem new Form CreateHandle Deadlock

    - by bogdanbrudiu
    I have a thread that needs to create a popup Window. I start the thread using ThreadPool.QueueUserWorkItem(new WaitCallback(CreatePopupinThread)) Thew thread creats a new form. The application freases in the new Form constructor at CreateHandle. The Worker Thread is locked... How can I fix this? this is how I create the form var form = new ConfirmationForm { Text = entry.Caption, Label = entry.Text, }; In the constructor the thread enters a deadlock public ConfirmationForm() { InitializeComponent(); }

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  • How does static code run with multiple threads?

    - by Krisc
    I was reading http://stackoverflow.com/questions/1511798/threading-from-within-a-class-with-static-and-non-static-methods and I am in a similar situation. I have a static method that pulls data from a resource and creates some runtime objects based on the data. static class Worker{ public static MyObject DoWork(string filename){ MyObject mo = new MyObject(); // ... does some work return mo; } } The method takes awhile (in this case it is reading 5-10mb files) and returns an object. I want to take this method and use it in a multiple thread situation so I can read multiple files at once. Design issues / guidelines aside, how would multiple threads access this code? Let's say I have something like this... class ThreadedWorker { public void Run() { Thread t = new Thread(OnRun); t.Start(); } void OnRun() { MyObject mo = Worker.DoWork("somefilename"); mo.WriteToConsole(); } } Does the static method run for each thread, allowing for parallel execution?

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