How to terminate a QThread?

Question

QThread::terminate() documentation states that it is discouraged to terminate a thread by calling this function.
In my program, I need to terminate a thread before it finishes execution. The thread is performing some heavy computation and I want the user to have control to stop calculation.
How can I do that instead of calling QThread::terminate()?

Answer 1

Set a flag from outside the thread that is checked by the computation within the thread and stop the calculation if the flag is set.

Answer 2

Using flags is an obvious and the most common way to do the trick, but if you are working on a linux/unix platform I would advise you to use pipes instead. I had the same issue where I used a flag (this makes the code threadunsafe, and bugs arising out of such a flag are hard to trace), then I changed the implementation to use pipes which were an efficient way to do the needful.

If you want, for a linux platform I can show you how to use pipes to terminate a QThread.

You may also have windows equivalent of pipes, which I don't know much about as I haven't done much of programming on Windows platform.

Hope this helps

Answer 3

Best is to use flag + mutex which will make the solution thread safe.