That did the trick! I worked around the deletion order by moving the code that's in the destructor into a function called stopTask(). Then, I call this from the child's destructor so the run loop will get stopped BEFORE CentralTask() becomes a pure virtual function again. Worked like a charm.

Here's the updated code:

Seth

Qt Code: 
  1. #ifndef INFINITETHREAD_H
  2. #define INFINITETHREAD_H
  3.  
  4. #include <QThread>
  5. #include <QMutex>
  6. #include <QWaitCondition>
  7.  
  8. class InfiniteThread : public QThread
  9. {
  10.     Q_OBJECT
  11.  
  12. public:
  13.     explicit InfiniteThread(QObject *parent = 0);
  14.     ~InfiniteThread();
  15.  
  16.     void startTask();
  17.     void stopTask();
  18.  
  19. signals:
  20.     void reportProgress(int pProg, QString message);
  21.     void taskDone(bool pSuccess);
  22.  
  23. protected:
  24.     void run();
  25.  
  26.     // Override this in the child class
  27.     virtual bool centralTask() = 0;
  28.  
  29.     QMutex mutex;
  30.     QWaitCondition condition;
  31.     bool restart;
  32.     bool abort;
  33. };
  34.  
  35. #endif // INFINITETHREAD_H
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Qt Code: 
  1. #include "infinitethread.h"
  2.  
  3. InfiniteThread::InfiniteThread(QObject *parent) :
  4.     QThread(parent)
  5. {    
  6.     restart = false;
  7.     abort = false;
  8. }
  9.  
  10. InfiniteThread::~InfiniteThread()
  11. {
  12. }
  13.  
  14. void InfiniteThread::stopTask()
  15. {
  16.     mutex.lock();
  17.     abort = true;
  18.     condition.wakeOne();
  19.     mutex.unlock();
  20.  
  21.     wait();
  22. }
  23.  
  24. void InfiniteThread::startTask()
  25. {
  26.     QMutexLocker locker(&mutex);
  27.  
  28.     if (!isRunning()) {
  29.         start(LowPriority);
  30.     } else {
  31.         restart = true;
  32.         condition.wakeOne();
  33.     }
  34. }
  35.  
  36. void InfiniteThread::run()
  37. {
  38.     forever {
  39.         // Perform central task
  40.         bool result = centralTask();
  41.         if(!restart) emit taskDone(result);
  42.  
  43.         // Abort thread if requested
  44.         if(abort) return;
  45.  
  46.         // Restart when new central task is given
  47.         mutex.lock();
  48.         if(!restart) condition.wait(&mutex);
  49.         restart = false;
  50.         mutex.unlock();
  51.     }
  52. }
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