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QProgressbar unresponsive with qthread

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  • M meganathan

    Hi,

    My requirement is that , i need to run the script , which will generate the n number of files, on creation of each file i need to update the progressbar .

    Running the script is part of separate thread. After script starts running , i am using QFileSystemWatcher to moniter the files has been created, if created i will increment the progress bar accordingly.

    Qprogressbar is not updating when script is executing, Please help me how can i implement this.

    JonBJ Offline
    JonBJ Offline
    JonB
    wrote on last edited by JonB
    #2

    @meganathan
    Something in your code is wrong then. How can anyone help if we have no idea what your code looks like? Have you tried getting a minimal example, presumably without needing file watchers etc., working in a separate thread, so that you have something simple to start from to get working?

    1 Reply Last reply
    1
    • Pradeep KumarP Offline
      Pradeep KumarP Offline
      Pradeep Kumar
      wrote on last edited by Pradeep Kumar
      #3

      Hi @meganathan ,

      can u post the code which u tried and the progressbar value will increase based on value provided to progressbar, check do u have provided the value for progressbar?.

      Thanks,

      Pradeep Kumar
      Qt,QML Developer

      1 Reply Last reply
      0
      • M Offline
        M Offline
        meganathan
        wrote on last edited by
        #4

        @JonB said in QProgressbar unresponsive with qthread:

        How can anyone help if we have no idea what your code looks like? Have you tried getting a minima

        FelixThread *ansysThread = new FelixThread(tempDirPath,ansysPath,felixMutex);
        ansysThread->start();
        qApp->processEvents(QEventLoop::ExcludeUserInputEvents);
        ansysThread->wait();

        this ansys thread will run my script ,
        Inside thread run()

        QProcess *process = new QProcess();
        process->setWorkingDirectory(QString(getenv("TEMP"))+"\Felix");
        process->start(""" + ansysPath1 + "" -b -i get_node_results.mac -o output.out");
        process->waitForFinished(-1);

        In constructor
        QFileSystemWatcher *watcher = new QFileSystemWatcher(this);
        watcher->addPath(QString(getenv("TEMP"))+"/Felix");

        QObject::connect(watcher,SIGNAL(directoryChanged(const QString &)),this,SLOT(directoryChanged(const QString &)));

        My question is , when ansysThread is started, does ansysthread->wait() blocks the progress bar update or process->waitforfinished(-1) is blocking the main GUI thread to update

        JonBJ J.HilkJ 2 Replies Last reply
        0
        • M meganathan

          @JonB said in QProgressbar unresponsive with qthread:

          How can anyone help if we have no idea what your code looks like? Have you tried getting a minima

          FelixThread *ansysThread = new FelixThread(tempDirPath,ansysPath,felixMutex);
          ansysThread->start();
          qApp->processEvents(QEventLoop::ExcludeUserInputEvents);
          ansysThread->wait();

          this ansys thread will run my script ,
          Inside thread run()

          QProcess *process = new QProcess();
          process->setWorkingDirectory(QString(getenv("TEMP"))+"\Felix");
          process->start(""" + ansysPath1 + "" -b -i get_node_results.mac -o output.out");
          process->waitForFinished(-1);

          In constructor
          QFileSystemWatcher *watcher = new QFileSystemWatcher(this);
          watcher->addPath(QString(getenv("TEMP"))+"/Felix");

          QObject::connect(watcher,SIGNAL(directoryChanged(const QString &)),this,SLOT(directoryChanged(const QString &)));

          My question is , when ansysThread is started, does ansysthread->wait() blocks the progress bar update or process->waitforfinished(-1) is blocking the main GUI thread to update

          JonBJ Offline
          JonBJ Offline
          JonB
          wrote on last edited by JonB
          #5

          @meganathan
          I don't even see any QProgressBar anywhere. I don't know if you have one, and even if you do where it is and which thread updates it. Maybe you & I have different expectations about what information you need to supply to ask a question/get an answer. Perhaps someone else can answer without knowing this.

          1 Reply Last reply
          0
          • M Offline
            M Offline
            meganathan
            wrote on last edited by
            #6

            Sorry ,forget to update that part.
            Creation:
            ProgressBarWidget = new QWidget();
            ProgressBarWidget->setWindowTitle("FELIXStudio");
            // ProgressBarWidget->setStyleSheet("");

            labell1 = new QLabel("Execution progress");
            ExecutionProgress = new QProgressBar();
            
            QLabel *warningLabel= new QLabel("Do not modify Ansys files");
            QPalette palette = warningLabel->palette();
            palette.setColor(warningLabel->backgroundRole(), Qt::white);
            palette.setColor(warningLabel->foregroundRole(), Qt::red);
            warningLabel->setPalette(palette);
            QVBoxLayout *vLayoutt3 = new QVBoxLayout();
            vLayoutt3->addWidget(labell1);
            vLayoutt3->addSpacing(3);
            vLayoutt3->addWidget(ExecutionProgress);
            vLayoutt3->addSpacing(5);
            vLayoutt3->addWidget(warningLabel);
            vLayoutt3->addStretch();
            

            Inside directorychangePart():

            for(int i=0;i<list1.size();i++)
            {
            strFileName = list1.at(i).fileName();
            if(strFileName.startsWith("R") && alreadyExecuted==false && QString::compare(strFileName,alreadyExecutedFilename)!=0)
            {
            alreadyExecuted = true;
            alreadyExecutedFilename = strFileName;
            //QMessageBox::information(0,"Info",strFileName);
            currentVal = ExecutionProgress->value()+progressVal;
            ExecutionProgress->setValue(currentVal);
            }
            else if(strFileName.contains("loadstep") && QString::compare(strFileName,alreadyExecutedloadset)!=0 && bExtractedFiles== true)
            {
            loadstepFound = true;
            alreadyExecutedloadset = strFileName;
            //QMessageBox::information(0,"Info",strFileName);
            ExecutionProgress->setValue(5);
            setNumberofRFiles(); //this will read the fileCount1
            progressVal = 15/fileCount1;
            }
            }

            1 Reply Last reply
            0
            • M meganathan

              @JonB said in QProgressbar unresponsive with qthread:

              How can anyone help if we have no idea what your code looks like? Have you tried getting a minima

              FelixThread *ansysThread = new FelixThread(tempDirPath,ansysPath,felixMutex);
              ansysThread->start();
              qApp->processEvents(QEventLoop::ExcludeUserInputEvents);
              ansysThread->wait();

              this ansys thread will run my script ,
              Inside thread run()

              QProcess *process = new QProcess();
              process->setWorkingDirectory(QString(getenv("TEMP"))+"\Felix");
              process->start(""" + ansysPath1 + "" -b -i get_node_results.mac -o output.out");
              process->waitForFinished(-1);

              In constructor
              QFileSystemWatcher *watcher = new QFileSystemWatcher(this);
              watcher->addPath(QString(getenv("TEMP"))+"/Felix");

              QObject::connect(watcher,SIGNAL(directoryChanged(const QString &)),this,SLOT(directoryChanged(const QString &)));

              My question is , when ansysThread is started, does ansysthread->wait() blocks the progress bar update or process->waitforfinished(-1) is blocking the main GUI thread to update

              J.HilkJ Offline
              J.HilkJ Offline
              J.Hilk
              Moderators
              wrote on last edited by
              #7

              @meganathan said in QProgressbar unresponsive with qthread:

              FelixThread *ansysThread = new FelixThread(tempDirPath,ansysPath,felixMutex);
              ansysThread->start();
              qApp->processEvents(QEventLoop::ExcludeUserInputEvents);
              ansysThread->wait();

              My question is , when ansysThread is started, does ansysthread->wait() blocks the progress bar update or process->waitforfinished(-1) is blocking the main GUI thread to update

              yes it does
              https://doc.qt.io/qt-5/qthread.html#wait


              Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


              Q: What's that?
              A: It's blue light.
              Q: What does it do?
              A: It turns blue.

              M 1 Reply Last reply
              4
              • J.HilkJ J.Hilk

                @meganathan said in QProgressbar unresponsive with qthread:

                FelixThread *ansysThread = new FelixThread(tempDirPath,ansysPath,felixMutex);
                ansysThread->start();
                qApp->processEvents(QEventLoop::ExcludeUserInputEvents);
                ansysThread->wait();

                My question is , when ansysThread is started, does ansysthread->wait() blocks the progress bar update or process->waitforfinished(-1) is blocking the main GUI thread to update

                yes it does
                https://doc.qt.io/qt-5/qthread.html#wait

                M Offline
                M Offline
                meganathan
                wrote on last edited by
                #8

                @J.Hilk hi,

                Is there any alternative function to Qthread::wait() which doesn't blocks main() GUI thread.

                J.HilkJ 1 Reply Last reply
                0
                • M meganathan

                  @J.Hilk hi,

                  Is there any alternative function to Qthread::wait() which doesn't blocks main() GUI thread.

                  J.HilkJ Offline
                  J.HilkJ Offline
                  J.Hilk
                  Moderators
                  wrote on last edited by
                  #9

                  @meganathan
                  well, yes, the finished signal
                  https://doc.qt.io/qt-5/qthread.html#finished


                  Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                  Q: What's that?
                  A: It's blue light.
                  Q: What does it do?
                  A: It turns blue.

                  M 1 Reply Last reply
                  4
                  • J.HilkJ J.Hilk

                    @meganathan
                    well, yes, the finished signal
                    https://doc.qt.io/qt-5/qthread.html#finished

                    M Offline
                    M Offline
                    meganathan
                    wrote on last edited by
                    #10

                    @J.Hilk

                    I tried like this
                    QEventLoop loop;
                    ansysThread->start();
                    loop.exec();
                    connect(ansysThread, SIGNAL(finished()),this,SLOT(onQProcessFinish()));

                    finished() signal emits before Qthread::run() completes the execution. Hot to approach this, if i use ansysthread->wait() it blocks the main GUI thread.. So please suggest any other suggestion.

                    jsulmJ 1 Reply Last reply
                    0
                    • M meganathan

                      @J.Hilk

                      I tried like this
                      QEventLoop loop;
                      ansysThread->start();
                      loop.exec();
                      connect(ansysThread, SIGNAL(finished()),this,SLOT(onQProcessFinish()));

                      finished() signal emits before Qthread::run() completes the execution. Hot to approach this, if i use ansysthread->wait() it blocks the main GUI thread.. So please suggest any other suggestion.

                      jsulmJ Offline
                      jsulmJ Offline
                      jsulm
                      Lifetime Qt Champion
                      wrote on last edited by
                      #11

                      @meganathan said in QProgressbar unresponsive with qthread:

                      QEventLoop loop;
                      ansysThread->start();
                      loop.exec();
                      connect(ansysThread, SIGNAL(finished()),this,SLOT(onQProcessFinish()));

                      Why do you block your thread with

                      loop.exec();
                      

                      ?!
                      It should be

                      connect(ansysThread, SIGNAL(finished()),this,SLOT(onQProcessFinish()));
                      ansysThread->start();
                      

                      https://forum.qt.io/topic/113070/qt-code-of-conduct

                      M 1 Reply Last reply
                      1
                      • jsulmJ jsulm

                        @meganathan said in QProgressbar unresponsive with qthread:

                        QEventLoop loop;
                        ansysThread->start();
                        loop.exec();
                        connect(ansysThread, SIGNAL(finished()),this,SLOT(onQProcessFinish()));

                        Why do you block your thread with

                        loop.exec();
                        

                        ?!
                        It should be

                        connect(ansysThread, SIGNAL(finished()),this,SLOT(onQProcessFinish()));
                        ansysThread->start();
                        
                        M Offline
                        M Offline
                        meganathan
                        wrote on last edited by
                        #12

                        @jsulm

                        I need to wait for thread to completed the process..how can i approach without using ansysthread->wait()

                        jsulmJ 1 Reply Last reply
                        0
                        • M meganathan

                          @jsulm

                          I need to wait for thread to completed the process..how can i approach without using ansysthread->wait()

                          jsulmJ Offline
                          jsulmJ Offline
                          jsulm
                          Lifetime Qt Champion
                          wrote on last edited by jsulm
                          #13

                          @meganathan Why do you need to wait? If you wait you block the waiting thread - and then you complain that the thread is blocking and progress bar not updating?! And if you want to wait then what is the point to use threads?
                          You get the finished() signal when it is finished and can do whatever needs to be done when the thread finishes.
                          Qt is asynchronous and you should avoid waiting for something. Learn how to program in an asynchronous way else there is no point to use Qt or threads.

                          https://forum.qt.io/topic/113070/qt-code-of-conduct

                          M 1 Reply Last reply
                          0
                          • jsulmJ jsulm

                            @meganathan Why do you need to wait? If you wait you block the waiting thread - and then you complain that the thread is blocking and progress bar not updating?! And if you want to wait then what is the point to use threads?
                            You get the finished() signal when it is finished and can do whatever needs to be done when the thread finishes.
                            Qt is asynchronous and you should avoid waiting for something. Learn how to program in an asynchronous way else there is no point to use Qt or threads.

                            M Offline
                            M Offline
                            meganathan
                            wrote on last edited by
                            #14

                            @jsulm
                            Based of the files generated by script inside ansysthread, i need to proceed after the script completes execution. i am struct there without using ansysthread->wait()

                            jsulmJ 1 Reply Last reply
                            0
                            • M meganathan

                              @jsulm
                              Based of the files generated by script inside ansysthread, i need to proceed after the script completes execution. i am struct there without using ansysthread->wait()

                              jsulmJ Offline
                              jsulmJ Offline
                              jsulm
                              Lifetime Qt Champion
                              wrote on last edited by
                              #15

                              @meganathan Again: you know when the thread finishes - you get the finished() signal. So, why don't you simply connect a slot to that signal and process in that slot?

                              https://forum.qt.io/topic/113070/qt-code-of-conduct

                              M 1 Reply Last reply
                              0
                              • jsulmJ jsulm

                                @meganathan Again: you know when the thread finishes - you get the finished() signal. So, why don't you simply connect a slot to that signal and process in that slot?

                                M Offline
                                M Offline
                                meganathan
                                wrote on last edited by
                                #16

                                @jsulm
                                By the time thread emits finished() signal, all my remaining things that to done(after script execution) are already executed. This makes no sense. By using QEventloop can we block the until thread emits finished() signal.?

                                J.HilkJ jsulmJ 2 Replies Last reply
                                0
                                • M meganathan

                                  @jsulm
                                  By the time thread emits finished() signal, all my remaining things that to done(after script execution) are already executed. This makes no sense. By using QEventloop can we block the until thread emits finished() signal.?

                                  J.HilkJ Offline
                                  J.HilkJ Offline
                                  J.Hilk
                                  Moderators
                                  wrote on last edited by
                                  #17

                                  @meganathan as a rule of thumb,

                                  if you're using QEventLoop or QProcessEvents, you're doing something wrong(95% chance).


                                  Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                                  Q: What's that?
                                  A: It's blue light.
                                  Q: What does it do?
                                  A: It turns blue.

                                  1 Reply Last reply
                                  2
                                  • M meganathan

                                    @jsulm
                                    By the time thread emits finished() signal, all my remaining things that to done(after script execution) are already executed. This makes no sense. By using QEventloop can we block the until thread emits finished() signal.?

                                    jsulmJ Offline
                                    jsulmJ Offline
                                    jsulm
                                    Lifetime Qt Champion
                                    wrote on last edited by
                                    #18

                                    @meganathan said in QProgressbar unresponsive with qthread:

                                    all my remaining things that to done(after script execution) are already executed

                                    Then do all these things in the slot connected to finished() signal as I already suggested.
                                    "By using QEventloop can we block the until thread emits finished() signal.?" - you can, but then your progress bar will not update which was your first question in this thread, right? And if you anyway want to block, then why do you want to use threads? I don't see the point...

                                    https://forum.qt.io/topic/113070/qt-code-of-conduct

                                    M 1 Reply Last reply
                                    0
                                    • J.HilkJ Offline
                                      J.HilkJ Offline
                                      J.Hilk
                                      Moderators
                                      wrote on last edited by
                                      #19

                                      here:

                                      #ifndef SUBTHREAD_H
                                      #define SUBTHREAD_H
                                      
                                      #include <QObject>
                                      #include <QThread>
                                      
                                      class SubThread : public QThread
                                      {
                                          Q_OBJECT
                                      public:
                                          explicit SubThread(QObject *parent = nullptr);
                                      
                                      protected:
                                          virtual void run()override;
                                      
                                      signals:
                                          void status(int stat);
                                      
                                      public slots:
                                      };
                                      
                                      #endif // SUBTHREAD_H
                                      
                                      
                                      #include "subthread.h"
                                      #include <QTime>
                                      
                                      SubThread::SubThread(QObject *parent) : QThread(parent)
                                      {
                                      
                                      }
                                      
                                      void SubThread::run()
                                      {
                                          QTime t;
                                          t.start();
                                      
                                          while(t.elapsed() < 10000){
                                              if(t.elapsed() % 100 == 0)
                                                  emit status(t.elapsed()/100);
                                          }
                                      }
                                      
                                      #include <QApplication>
                                      #include <QProgressBar>
                                      #include "subthread.h"
                                      
                                      int main(int argc, char *argv[])
                                      {
                                          QApplication a(argc, argv);
                                      
                                          QProgressBar bar;
                                          bar.show();
                                      
                                          SubThread myThread;
                                      
                                          QObject::connect(&myThread, &SubThread::status, &bar, &QProgressBar::setValue);
                                          QObject::connect(&myThread, &SubThread::finished, &a, &QApplication::quit);
                                          myThread.start();
                                      
                                      
                                          return  a.exec();
                                      }
                                      

                                      Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                                      Q: What's that?
                                      A: It's blue light.
                                      Q: What does it do?
                                      A: It turns blue.

                                      JonBJ 1 Reply Last reply
                                      1
                                      • J.HilkJ J.Hilk

                                        here:

                                        #ifndef SUBTHREAD_H
                                        #define SUBTHREAD_H
                                        
                                        #include <QObject>
                                        #include <QThread>
                                        
                                        class SubThread : public QThread
                                        {
                                            Q_OBJECT
                                        public:
                                            explicit SubThread(QObject *parent = nullptr);
                                        
                                        protected:
                                            virtual void run()override;
                                        
                                        signals:
                                            void status(int stat);
                                        
                                        public slots:
                                        };
                                        
                                        #endif // SUBTHREAD_H
                                        
                                        
                                        #include "subthread.h"
                                        #include <QTime>
                                        
                                        SubThread::SubThread(QObject *parent) : QThread(parent)
                                        {
                                        
                                        }
                                        
                                        void SubThread::run()
                                        {
                                            QTime t;
                                            t.start();
                                        
                                            while(t.elapsed() < 10000){
                                                if(t.elapsed() % 100 == 0)
                                                    emit status(t.elapsed()/100);
                                            }
                                        }
                                        
                                        #include <QApplication>
                                        #include <QProgressBar>
                                        #include "subthread.h"
                                        
                                        int main(int argc, char *argv[])
                                        {
                                            QApplication a(argc, argv);
                                        
                                            QProgressBar bar;
                                            bar.show();
                                        
                                            SubThread myThread;
                                        
                                            QObject::connect(&myThread, &SubThread::status, &bar, &QProgressBar::setValue);
                                            QObject::connect(&myThread, &SubThread::finished, &a, &QApplication::quit);
                                            myThread.start();
                                        
                                        
                                            return  a.exec();
                                        }
                                        
                                        JonBJ Offline
                                        JonBJ Offline
                                        JonB
                                        wrote on last edited by
                                        #20

                                        @J.Hilk

                                          while(t.elapsed() < 10000){
                                        

                                        Now, you doubtless know more than I about threads, because I don't use them. But I don't get this approach. It looks like you're spinning an awfully busy loop. It's true than your main thread will run uninterrupted, but half the CPU will be executing this all the time/your mobile battery is going to drain, no? Could you explain?

                                        This is why the OP is asking about QEventLoop etc. Does a QThread run its own event loop? Does it exit when it gets to end of run() or does it have to be terminated explicitly?

                                        jsulmJ J.HilkJ 2 Replies Last reply
                                        0
                                        • JonBJ JonB

                                          @J.Hilk

                                            while(t.elapsed() < 10000){
                                          

                                          Now, you doubtless know more than I about threads, because I don't use them. But I don't get this approach. It looks like you're spinning an awfully busy loop. It's true than your main thread will run uninterrupted, but half the CPU will be executing this all the time/your mobile battery is going to drain, no? Could you explain?

                                          This is why the OP is asking about QEventLoop etc. Does a QThread run its own event loop? Does it exit when it gets to end of run() or does it have to be terminated explicitly?

                                          jsulmJ Offline
                                          jsulmJ Offline
                                          jsulm
                                          Lifetime Qt Champion
                                          wrote on last edited by
                                          #21

                                          @JonB I think this is just a simple example not optimised for real world usage :-)

                                          https://forum.qt.io/topic/113070/qt-code-of-conduct

                                          1 Reply Last reply
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