[Development] Community effort in updating Qt5 docs -- QThread focus

[João Abecasis]

João Abecasis wrote:
> Chris Meyer wrote:
>> The documentation promotes the idea of using 'moveToThread' as a
>> preferred threading mechanism. However, we've found that moveToThread
>> is full of pitfalls.
>>
>> Particularly, an object must be deleted on the thread on which it
>> resides. This makes it difficult to manage the lifetime of objects
>> that have been moved to a thread via moveToThread. You need to
>> configure an independent mechanism to delete objects that have been
>> moved to thread (i.e. send a signal to the thread that it's about to
>> shutdown and allow the objects to deleteLater within the thread, which
>> also implies that you need to keep track of the objects that are
>> within the thread, which somewhat defeats the apparent simplicity of
>> moveToThread). Also, you cannot use the finished signal from the
>> thread since the thread will already be gone by then.
>
> Since Qt 4.8 you can connect QThread::finished to QObject::deleteLater
> and it should do the right thing in the appropriate thread.

For reference, here's a link to the commit implementing this:

    http://qt.gitorious.org/qt/qt/commit/0c643b179c5154c50b61dba421016b7b48794720

>> The bug will show up intermittently and differently on various
>> platforms and is difficult to debug if you don't know about the
>> problem. You'll just end up with spurious crashes (typically at quit
>> time), especially for networking objects.

Cheers,


João