[PyQt] Any way to run code before each QThread?

[Florian Bruhin]

On Sun, Jul 15, 2018 at 04:43:41PM +0200, David Boddie wrote:
> On Sun Jul 15 12:30:55 BST 2018, Ned Batchelder wrote:
> 
> > I maintain coverage.py.  I have an issue
> > (https://github.com/nedbat/coveragepy/issues/582) that the code running
> > in QThreads aren't measured.  For the stdlib threading module, I have
> > code that runs as each thread is created to start the measurement.  Is
> > there any way to do the same for QThreads?
> 
> Perhaps. See below.
> 
> > The stdlib feature is threading.settrace
> > (https://docs.python.org/3/library/threading.html#threading.settrace). I
> > didn't see anything similar for QThreads, or any other hook that would
> > give me control before the thread starts running.  Am I overlooking
> > something?
> 
> From the threading.settrace docs:
> 
>  "Set a trace function for all threads started from the threading module.
>  The func will be passed to sys.settrace() for each thread, before its run()
>  method is called."
> 
> The QThread.started signal docs (https://doc.qt.io/qt-5/qthread.html#started)
> say this:
> 
>  "This signal is emitted from the associated thread when it starts executing,
>  before the run() function is called."
> 
> So it looks like almost exactly what you want. Connect this signal to a slot
> (function/method) and perform the same setup there.

That's only for a given QThread instance though - it'd probably work if
you could somehow find out about all QThread instances created in a
project, but I can't think of a good way to do that.

Florian

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