QThread: Destroyed while thread is still running

Wang xiaohu

When I use Qt multithreading, I encounter this problem: "QThread: Destroyed while thread is still running".

The MainWindow.h :

class MainWindow : public QMainWindow 
{
.....
private:
    QThread TerraThread;
    TerraWorker* terraWorker = NULL;
}

The MainWindow.cpp :

MainWindow::MainWindow()
{
    terraWorker = new TerraWorker;
    terraWorker->moveToThread(&TerraThread);
    connect(terraWorker, &QObject::destroyed, &TerraThread, &QThread::quit);
    connect(&TerraThread, &QThread::finished, terraWorker, &QObject::deleteLater);
    connect(&TerraThread, &QThread::started, terraWorker, &TerraWorker::init);
    TerraThread.start();
}

The terraWoker.h :

#pragma once
#include <QObject>
#include "terrasinkevent.h"

class TerraWorker :   public QObject
{
	Q_OBJECT

public:
	//TerraWorker();
	//~TerraWorker();

public slots:
	void init();
private:

signals:

private:
	TerraSinkEvent* m_pTerraSink = NULL;
	ISGWorld71Ptr m_pISGWorld = NULL;
};

The terraWorker.cpp :

#include "terraworker.h"
#include <QDebug>
#include <QtCore/QThread> 

 void TerraWorker::init()
 {
     CoInitialize(NULL);
     
     //TerraSinkEvent* m_pTerraSink = new TerraSinkEvent();
     //ISGWorld71Ptr m_pISGWorld = NULL;
     m_pTerraSink = new TerraSinkEvent();
     m_pISGWorld.CreateInstance(CLSID_SGWorld71);
     if (m_pISGWorld != NULL)
     {
         HRESULT hr = m_pTerraSink->DispEventAdvise(m_pISGWorld);
         if (FAILED(hr))
         {
             qDebug() << "DispEventAdvise Failed...";
         }
     }
     m_pISGWorld->Project->Open("C:\\Skyline\\TerraExplorer\\Beijing-15\\Beijing_15.FLY", FALSE, "", "");
     IPosition71Ptr pIPosition71 = m_pISGWorld->Creator->CreatePosition(116.2, 40.4, 1500, AltitudeTypeCode::ATC_TERRAIN_RELATIVE, 0, 0, 0, 0);
     m_pISGWorld->Navigate->FlyTo(_variant_t((IDispatch*)pIPosition71), ActionCode::AC_FLYTO);
     qDebug() << "TerraWorker Thread: " << QThread::currentThreadId();
 }

The terrasinkevent.h :

#pragma once

#include <atlbase.h>
#include <atlcom.h>
#include <QDebug>

#include "terraexplorerx.tlh"

static _ATL_FUNC_INFO info = { CC_STDCALL, VT_EMPTY, 1, {VT_BOOL} };
static _ATL_FUNC_INFO onLButtonDownInfo = { CC_STDCALL, VT_EMPTY, 3, {VT_I4, VT_I4, VT_I4 } };
static _ATL_FUNC_INFO infoEmpty = { CC_STDCALL, VT_EMPTY, 0, {} };


    class  TerraSinkEvent : public IDispEventSimpleImpl
                <1, TerraSinkEvent, &DIID__ISGWorld71Events>
{
public:
    TerraSinkEvent();

    ~TerraSinkEvent();

    STDMETHODIMP OnLButtonDown(long Flags, int X, int Y, VARIANT_BOOL* pbHandled)
    {
        qDebug() << "Jump into OnLButtonDown...";
        return S_OK;
    }

    STDMETHODIMP OnLoadFinished(VARIANT_BOOL bSuccess)
    {
        return S_OK;
    }


    BEGIN_SINK_MAP(TerraSinkEvent)
        SINK_ENTRY_INFO(1, DIID__ISGWorld71Events, 9, OnLButtonDown, &onLButtonDownInfo)
    END_SINK_MAP()

};

The * terrasinkevent.cpp* :

#include "terrasinkevent.h"

TerraSinkEvent::TerraSinkEvent()
{

 }

TerraSinkEvent::  ~TerraSinkEvent()
{
 
}

I think I use the QThread in right way, but, why it arises "QThread: Destroyed while thread is still running", when I quit the "MainWindow"?

When I comment these lines in MainWindow.cpp :

    //terraWorker->moveToThread(&TerraThread);
    //connect(terraWorker, &QObject::destroyed, &TerraThread, &QThread::quit);
    //connect(&TerraThread, &QThread::finished, terraWorker, &QObject::deleteLater);
    //connect(&TerraThread, &QThread::started, terraWorker, &TerraWorker::init);
    //TerraThread.start();

And use :

    terraWorker = new TerraWorker;
    terraWorker->init();

This doesn't arise this error, when I quit MainWindow.

JKSH

@Wang-xiaohu said in QThread: Destroyed while thread is still running:

why it arises "QThread: Destroyed while thread is still running
", when I quit the "MainWindow"?

Because you destroyed the QThread object when the thread was still running.

You must wait until the thread stops. Call QThread::wait() in your MainWindow's destructor.

Wang xiaohu

thank you, I'll have a try.
I thought it would be OK to use QThread::quit() function.

JKSH

@Wang-xiaohu said in QThread: Destroyed while thread is still running:

I thought it would be OK to use QThread::quit() function.

QThread::quit() causes the thread to begin shutting down.

QThread::wait() waits for the thread to finish shutting down.