Skip to content
  • Categories
  • Recent
  • Tags
  • Popular
  • Users
  • Groups
  • Search
  • Get Qt Extensions
  • Unsolved
Collapse
Brand Logo
  1. Home
  2. Qt Development
  3. General and Desktop
  4. Memory leak using QThread issue
Forum Updated to NodeBB v4.3 + New Features

Memory leak using QThread issue

Scheduled Pinned Locked Moved Solved General and Desktop
35 Posts 5 Posters 13.7k Views 2 Watching
  • Oldest to Newest
  • Newest to Oldest
  • Most Votes
Reply
  • Reply as topic
Log in to reply
This topic has been deleted. Only users with topic management privileges can see it.
  • J.HilkJ J.Hilk

    @Cobra91151 said in Memory leak using QThread issue:

    So should I connection like this:

    connect(appCheckUpdate, &CheckUpdates::finished, appCheckUpdatesThread, &QThread::quit);
    connect(appCheckUpdatesThread, &CheckUpdates::destroyed, appCheckUpdatesThread, &QThread::deleteLater);
    

    Or it will not work because the thread is not destroyed?

    No, this is exactly the correct way to do it.

    Cobra91151C Offline
    Cobra91151C Offline
    Cobra91151
    wrote on last edited by Cobra91151
    #9

    @J.Hilk

    I have changed code to:

     appCheckUpdate = new CheckUpdates();
     appCheckUpdatesThread = new QThread();
     appCheckUpdate->moveToThread(appCheckUpdatesThread);
     connect(appCheckUpdatesThread, &QThread::started, appCheckUpdate, &CheckUpdates::checkUpdate);
     connect(appCheckUpdate, &CheckUpdates::updateData, this, &Changelog::getUpdateData);
     connect(appCheckUpdate, &CheckUpdates::networkError, this, &Changelog::changeLogUpdateError);
     connect(appCheckUpdate, &CheckUpdates::localeError, this, &Changelog::updateLocaleError);
     connect(appCheckUpdate, &CheckUpdates::finished, appCheckUpdatesThread, &QThread::quit);
     connect(appCheckUpdatesThread, &CheckUpdates::destroyed, appCheckUpdatesThread, &QThread::deleteLater);
     appCheckUpdatesThread->start();
    

    But the problem still exists, it leaks memory. So this - connect(appCheckUpdatesThread, &CheckUpdates::destroyed, appCheckUpdatesThread, &QThread::deleteLater); - deletes only appCheckUpdatesThread (QThread) object.

    So should I also delete appCheckUpdate by calling delete appCheckUpdate?

    J.HilkJ jsulmJ 2 Replies Last reply
    0
    • Cobra91151C Cobra91151

      @J.Hilk

      I have changed code to:

       appCheckUpdate = new CheckUpdates();
       appCheckUpdatesThread = new QThread();
       appCheckUpdate->moveToThread(appCheckUpdatesThread);
       connect(appCheckUpdatesThread, &QThread::started, appCheckUpdate, &CheckUpdates::checkUpdate);
       connect(appCheckUpdate, &CheckUpdates::updateData, this, &Changelog::getUpdateData);
       connect(appCheckUpdate, &CheckUpdates::networkError, this, &Changelog::changeLogUpdateError);
       connect(appCheckUpdate, &CheckUpdates::localeError, this, &Changelog::updateLocaleError);
       connect(appCheckUpdate, &CheckUpdates::finished, appCheckUpdatesThread, &QThread::quit);
       connect(appCheckUpdatesThread, &CheckUpdates::destroyed, appCheckUpdatesThread, &QThread::deleteLater);
       appCheckUpdatesThread->start();
      

      But the problem still exists, it leaks memory. So this - connect(appCheckUpdatesThread, &CheckUpdates::destroyed, appCheckUpdatesThread, &QThread::deleteLater); - deletes only appCheckUpdatesThread (QThread) object.

      So should I also delete appCheckUpdate by calling delete appCheckUpdate?

      J.HilkJ Offline
      J.HilkJ Offline
      J.Hilk
      Moderators
      wrote on last edited by
      #10

      @Cobra91151
      yes of course,
      at the end of your threaded operation, you'll have to delete your QThread object and your Worker object, seperately.

      In case you haven't seen it, heres an wiki-example


      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.

      Cobra91151C 2 Replies Last reply
      1
      • J.HilkJ J.Hilk

        @Cobra91151
        yes of course,
        at the end of your threaded operation, you'll have to delete your QThread object and your Worker object, seperately.

        In case you haven't seen it, heres an wiki-example

        Cobra91151C Offline
        Cobra91151C Offline
        Cobra91151
        wrote on last edited by
        #11

        @J.Hilk

        Thanks for the link. I will try it.

        1 Reply Last reply
        0
        • Cobra91151C Cobra91151

          @J.Hilk

          I have changed code to:

           appCheckUpdate = new CheckUpdates();
           appCheckUpdatesThread = new QThread();
           appCheckUpdate->moveToThread(appCheckUpdatesThread);
           connect(appCheckUpdatesThread, &QThread::started, appCheckUpdate, &CheckUpdates::checkUpdate);
           connect(appCheckUpdate, &CheckUpdates::updateData, this, &Changelog::getUpdateData);
           connect(appCheckUpdate, &CheckUpdates::networkError, this, &Changelog::changeLogUpdateError);
           connect(appCheckUpdate, &CheckUpdates::localeError, this, &Changelog::updateLocaleError);
           connect(appCheckUpdate, &CheckUpdates::finished, appCheckUpdatesThread, &QThread::quit);
           connect(appCheckUpdatesThread, &CheckUpdates::destroyed, appCheckUpdatesThread, &QThread::deleteLater);
           appCheckUpdatesThread->start();
          

          But the problem still exists, it leaks memory. So this - connect(appCheckUpdatesThread, &CheckUpdates::destroyed, appCheckUpdatesThread, &QThread::deleteLater); - deletes only appCheckUpdatesThread (QThread) object.

          So should I also delete appCheckUpdate by calling delete appCheckUpdate?

          jsulmJ Offline
          jsulmJ Offline
          jsulm
          Lifetime Qt Champion
          wrote on last edited by
          #12

          @Cobra91151 It should be:

          connect(appCheckUpdatesThread, &QThread::finished, appCheckUpdatesThread, &QThread::deleteLater);
          

          In http://doc.qt.io/qt-5.8/qthread.html#finished
          "This signal can be connected to QObject::deleteLater(), to free objects in that thread."

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

          1 Reply Last reply
          2
          • J.HilkJ J.Hilk

            @Cobra91151
            yes of course,
            at the end of your threaded operation, you'll have to delete your QThread object and your Worker object, seperately.

            In case you haven't seen it, heres an wiki-example

            Cobra91151C Offline
            Cobra91151C Offline
            Cobra91151
            wrote on last edited by
            #13

            @J.Hilk

            Thank you. I have fixed the memory leak issue with changelog, but I also have the memory leak when I reload some WMI data during language change of my app. I will try to fix it and reply.

            1 Reply Last reply
            0
            • Cobra91151C Offline
              Cobra91151C Offline
              Cobra91151
              wrote on last edited by Cobra91151
              #14

              Hi! I have some WMI memory leak issue.

              Code:

              //Initialization
              IWbemLocator *pLocator = 0;
              IWbemServices *pService = 0;
              IEnumWbemClassObject* pEnumerator = NULL;
              IWbemClassObject *pclsObj = NULL;
              
              while (pEnumerator)
              {
                   hres = pEnumerator->Next(WBEM_INFINITE, 1, &pclsObj, &uReturn);
              
                    VARIANT processName;
                    pclsObj->Get(L"Name", 0, &processName, 0, 0);
                    QString userProcessName;
                    userProcessName = QString::fromWCharArray(processName.bstrVal);
                     
                    emit testData(userProcessName);
                    VariantClear(&processName);
              }
              
              //Cleanup
               pService->Release();
               pLocator->Release();
               //pEnumerator->Release(); - Clang Static Analyzer displays issue - called C++ object pointer is null
               //pclsObj->Release(); - Clang Static Analyzer displays issue - called C++ object pointer is null
              

              Every time I change language in my app it takes 1 - 5 MB RAM. How to fix this issue? Thanks in advance.

              A 1 Reply Last reply
              0
              • Cobra91151C Cobra91151

                Hi! I have some WMI memory leak issue.

                Code:

                //Initialization
                IWbemLocator *pLocator = 0;
                IWbemServices *pService = 0;
                IEnumWbemClassObject* pEnumerator = NULL;
                IWbemClassObject *pclsObj = NULL;
                
                while (pEnumerator)
                {
                     hres = pEnumerator->Next(WBEM_INFINITE, 1, &pclsObj, &uReturn);
                
                      VARIANT processName;
                      pclsObj->Get(L"Name", 0, &processName, 0, 0);
                      QString userProcessName;
                      userProcessName = QString::fromWCharArray(processName.bstrVal);
                       
                      emit testData(userProcessName);
                      VariantClear(&processName);
                }
                
                //Cleanup
                 pService->Release();
                 pLocator->Release();
                 //pEnumerator->Release(); - Clang Static Analyzer displays issue - called C++ object pointer is null
                 //pclsObj->Release(); - Clang Static Analyzer displays issue - called C++ object pointer is null
                

                Every time I change language in my app it takes 1 - 5 MB RAM. How to fix this issue? Thanks in advance.

                A Offline
                A Offline
                ambershark
                wrote on last edited by
                #15

                @Cobra91151 This isn't Qt code.. You should probably post this question on a win32 API message board.

                Also are you sure it's actually leaking? Just because the size of memory for your running application grows does not mean it's leaking. You need something like valgrind to test for leaks on exit.

                My L-GPL'd C++ Logger github.com/ambershark-mike/sharklog

                Cobra91151C A 2 Replies Last reply
                1
                • A ambershark

                  @Cobra91151 This isn't Qt code.. You should probably post this question on a win32 API message board.

                  Also are you sure it's actually leaking? Just because the size of memory for your running application grows does not mean it's leaking. You need something like valgrind to test for leaks on exit.

                  Cobra91151C Offline
                  Cobra91151C Offline
                  Cobra91151
                  wrote on last edited by Cobra91151
                  #16

                  @ambershark

                  I have checked it in Task Manager. For example, my app takes 25 MB RAM, when changing languages it grows to 30 MB and 35, 40... and never release it. So should I consider this as not a leak?

                  1 Reply Last reply
                  0
                  • SGaistS Offline
                    SGaistS Offline
                    SGaist
                    Lifetime Qt Champion
                    wrote on last edited by
                    #17

                    What do you mean by changing languages ? What do you do to make that happen ?

                    Interested in AI ? www.idiap.ch
                    Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                    Cobra91151C 1 Reply Last reply
                    0
                    • SGaistS SGaist

                      What do you mean by changing languages ? What do you do to make that happen ?

                      Cobra91151C Offline
                      Cobra91151C Offline
                      Cobra91151
                      wrote on last edited by Cobra91151
                      #18

                      @SGaist

                      I have all WMI data in QTreeWidgetItems (QTreeWidget). I have two columns:
                      1 - Property
                      2 - Data

                      Property and data I get from a worker class which connected with signals and slots to thread. So to change property to another language I call clear function on QTreeWidget to delete all property and data, then I call function which connects worker to thread and get this data as QTreeWidgetItems in chosen (translated) language.

                      1 Reply Last reply
                      0
                      • SGaistS Offline
                        SGaistS Offline
                        SGaist
                        Lifetime Qt Champion
                        wrote on last edited by
                        #19

                        Are you loading any language file in order to provide translations ?

                        Interested in AI ? www.idiap.ch
                        Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                        Cobra91151C 1 Reply Last reply
                        0
                        • SGaistS SGaist

                          Are you loading any language file in order to provide translations ?

                          Cobra91151C Offline
                          Cobra91151C Offline
                          Cobra91151
                          wrote on last edited by Cobra91151
                          #20

                          @SGaist

                          Yes, but when QComboBox index changes I call this function to load appropriate translation file:

                          Some code:

                          appTranslator = new QTranslator(this);
                          qApp->removeTranslator(appTranslator);
                          appTranslator->load(":Localization/Test_ru.qm");
                           qApp->installTranslator(appTranslator);
                          

                          and when apply button is clicked I retranslate string and reload WMI data using my loadTraslatedText function

                          1 Reply Last reply
                          0
                          • SGaistS Offline
                            SGaistS Offline
                            SGaist
                            Lifetime Qt Champion
                            wrote on last edited by
                            #21

                            Your code has one tiny problem: you are removing the translator you just created and then you add it again after loading the translation file, so basically you never remove anything and just keep adding new ones.

                            Interested in AI ? www.idiap.ch
                            Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                            Cobra91151C 1 Reply Last reply
                            0
                            • SGaistS SGaist

                              Your code has one tiny problem: you are removing the translator you just created and then you add it again after loading the translation file, so basically you never remove anything and just keep adding new ones.

                              Cobra91151C Offline
                              Cobra91151C Offline
                              Cobra91151
                              wrote on last edited by Cobra91151
                              #22

                              @SGaist

                              I have changed code:

                              appTranslator = new QTranslator(this);
                              appTranslator->load(":Localization/Test_ru.qm");
                               qApp->installTranslator(appTranslator);
                              

                              But the leak is still exists.

                              1 Reply Last reply
                              0
                              • SGaistS Offline
                                SGaistS Offline
                                SGaist
                                Lifetime Qt Champion
                                wrote on last edited by
                                #23

                                Isn't it the same code as before ?

                                Interested in AI ? www.idiap.ch
                                Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                                Cobra91151C 1 Reply Last reply
                                1
                                • SGaistS SGaist

                                  Isn't it the same code as before ?

                                  Cobra91151C Offline
                                  Cobra91151C Offline
                                  Cobra91151
                                  wrote on last edited by Cobra91151
                                  #24

                                  @SGaist

                                  Check again. I have copied the wrong one.

                                  I don't think that the problem is with language change function itself, because when I have commented the getWMIData function no leak is found.

                                  So the problem is with actual getWMIData which contains other functions such as osData, cpuData.... which lead to worker class which has about 10 thousand lines of code.

                                  I think the only way to fix this, is to figure out how to change all properties to appropriate language without reloading their data.

                                  1 Reply Last reply
                                  0
                                  • SGaistS Offline
                                    SGaistS Offline
                                    SGaist
                                    Lifetime Qt Champion
                                    wrote on last edited by
                                    #25

                                    You are still still adding one new translator each time you change the language, start by fixing that. Remove the one currently installed and then load the new one.

                                    Interested in AI ? www.idiap.ch
                                    Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                                    Cobra91151C 1 Reply Last reply
                                    0
                                    • SGaistS SGaist

                                      You are still still adding one new translator each time you change the language, start by fixing that. Remove the one currently installed and then load the new one.

                                      Cobra91151C Offline
                                      Cobra91151C Offline
                                      Cobra91151
                                      wrote on last edited by Cobra91151
                                      #26

                                      @SGaist

                                      So I put initialization of translator (appTranslator = new QTranslator(this);) in the constructor.

                                      appTranslator->load(":Localization/Test_ru.qm");
                                      qApp->installTranslator(appTranslator);
                                      

                                      Then I have added qApp->removeTranslator(appTranslator); at the end to loadTraslatedText function, but now my other windows are not translated (when I open them). The problem is with qApp->removeTranslator(appTranslator); So where to remove the one currently installed?

                                      1 Reply Last reply
                                      0
                                      • A ambershark

                                        @Cobra91151 This isn't Qt code.. You should probably post this question on a win32 API message board.

                                        Also are you sure it's actually leaking? Just because the size of memory for your running application grows does not mean it's leaking. You need something like valgrind to test for leaks on exit.

                                        A Offline
                                        A Offline
                                        ambershark
                                        wrote on last edited by
                                        #27

                                        @ambershark said in Memory leak using QThread issue:

                                        @Cobra91151 This isn't Qt code.. You should probably post this question on a win32 API message board.

                                        Also are you sure it's actually leaking? Just because the size of memory for your running application grows does not mean it's leaking. You need something like valgrind to test for leaks on exit.

                                        Yea checking active running memory does not show you leaks. If it changes in task manager that is ok, if when you exit the app there are still pointers to memory that didn't get cleaned up then those are leaks.

                                        If as you watch your program run and be used it is constantly growing while running in the task manager that can be a leak too, but not just because you did something like allocate a new language.

                                        The way memory usually works is block are allocated and freed as they are needed. So if you allocate a new block, even though you delete your old one, the OS doesn't necessarily reclaim that memory unless it is needed. So in task manager you would see it change unless you were out of memory then you would see it reclaimed.

                                        So unless you see it constantly growing and growing, out of control, while running it's probably not leaking. That is why you need a tool like valgrind to detect actual leaks.

                                        My L-GPL'd C++ Logger github.com/ambershark-mike/sharklog

                                        Cobra91151C 1 Reply Last reply
                                        0
                                        • SGaistS Offline
                                          SGaistS Offline
                                          SGaist
                                          Lifetime Qt Champion
                                          wrote on last edited by
                                          #28
                                          1. Remove the currently loaded translator
                                          2. Delete it
                                          3. Create the new translator
                                          4. Install it

                                          Interested in AI ? www.idiap.ch
                                          Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                                          Cobra91151C 2 Replies Last reply
                                          2

                                          • Login

                                          • Login or register to search.
                                          • First post
                                            Last post
                                          0
                                          • Categories
                                          • Recent
                                          • Tags
                                          • Popular
                                          • Users
                                          • Groups
                                          • Search
                                          • Get Qt Extensions
                                          • Unsolved