QThreadPool backup example

Question

Can someone provide an example of using "reserveThread" and / or "releaseThread" from the QThreadPool class? I read the documentation, but I do not understand when you will use these functions. Internet searches look empty.

I use PySide, so Python would be preferable, but C ++ is good too.

Answer 1

These methods are used to interact with a thread pool with threads that you manually manage.

, , . reserveThread releaseThread , . . , QThread.

reserveThread : " , , , , , , ( ).

releaseThread : " , ".

: . - ++.

• :

  QThreadPool pool;
  assert(pool.maxThreadCount() == 4);
  assert(pool.activeThreadCount() == 0);
  

• : ​​ . , reserveThread:

  MyWorker worker;
  QThread thread;
  worker.moveToThread(&thread);
  thread.start();
  pool.reserveThread();
  assert(pool.activeThreadCount() == 1);
  

  !

• runnables, . :

  QAtomicInt act = 0;
  QtConcurrent.run(&pool, [&]{ act.ref(); QThread::sleep(60); act.deref();  });
  QtConcurrent.run(&pool, [&]{ act.ref(); QThread::sleep(60); act.deref();  });
  QtConcurrent.run(&pool, [&]{ act.ref(); QThread::sleep(60); act.deref();  });
  QtConcurrent.run(&pool, [&]{ act.ref(); QThread::sleep(60); act.deref();  });
  QThread::sleep(1);
  assert(pool.activeThreadCount() == 4);
  assert(act.load() == 3);
  

  runnables, : , .

• , . , releaseThread:

  thread.quit();
  thread.wait();
  pool.releaseThread();
  QThread::sleep(1);
  assert(pool.activeThreadCount() == 4);
  assert(act.load() == 4);
  

  runnable, , runnable.

• , :

  QThread::sleep(60);
  assert(pool.activeThreadCount() == 0);
  assert(act.load() == 0);