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multithreadingeventsqtthreadpoolsignals-slots

Emit signals or post events from QRunnable

Is emitting signals inside QRunnable::run() a right thing to do? I need to inform my GUI thread that image processed by QRunnable is done. I am using QThreadPool/QRunnable because I need to be able to add new tasks to the pool while there are tasks in it already. I find it kind of hard to do that with QtConcurrent and QFutureWatcher.

The QRunnable is using a QObject created in run() to connect to the target QObject and emit signals.

If emitting from QRunnable is not a good thing, is it possible to post events from there?

Solution

  • Yes, emitting signals and posting events are fine things to do in a QRunnable::run() because they are both thread-safe. For the signals and events to be handled properly, the QObjects must have the correct thread affinity. See Threads and QObjects for more details.