[Interest] Poor QMethod::invoke performance across threads on i.MX53

[Thiago Macieira]

On Wednesday 27 May 2015 17:16:54 Matthew Woehlke wrote:
> Right. An example probably helps. What's wrong with this approach?
> 
>   class MyThread : public QThread { ... } // has moveToThread(this)
> 
>   int main()
>   {
>     auto* t = new MyThread;
>     t.start();
>     // ...
>     t.wait();
>     delete t; // QThread deleted from main thread, not itself
>   }

You cannot delete t; while the t object is associated with the other thread.

Do you have a moveToThread(nullptr) or moveToThread(mainThread)? If so, where? 
That's what my examples were trying to show.

> The QThread is memory-managed from a thread other than itself. It's just
> that the thread affinity is circular. Note that I am *NOT* trying to
> deleteLater the QObject! (Because, yes, that would be horrible! And for
> that matter, would leak, since in my usage, the thread has exited before
> I try to delete it.)
> 
> Anyway, a more accurate depiction of my case is:
> 
>   class MyThread : public QObject
>   {
>     QThread self;
>     MyThread() { moveToThread(self); }
>   }
> 
> ...where again, it is assumed that MyThread is deleted from a thread
> other than MyThread::self. Is this approach broken? (I think no? It
> seems similar to the alternate approach you gave.)

Again missing the move-back.

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center