Review Request: Workaround for the hang (freeze) when opening VLC's file dialog under KDE...

Thiago Macieira thiago at
Fri Feb 4 23:05:41 GMT 2011

On Friday, 4 de February de 2011 17:35:00 Dawit A wrote:
> > Ok, that sounds like unexpected behaviour. Has this been filed as a bug?
> Not yet. I simply mentioned it here because you seem to be addressing
> the issue that exposed this behavior, but I guess I can open a ticket
> against Qt for this.

Well, I thought you meant in a scenario QProcess's internals are still working 
as expected.

The moment that VLC blocked the registration of QProcess's signal handler 
(this was the source of the issue), all bets are off.

> Yep, I do. It is the same thing I cobbled together to replicate the
> VLC hang bug and posted a while back. I can dust that up and create
> bug reports against Qt if you like.

Again that's interfering with SIGCHLD. I need a testcase that doesn't break 
that functionality.

It's perfectly possible for other libraries and the application to use SIGCHLD 
too without breaking QProcess. VLC doesn't want to play ball with us, so 
there's nothing we can do, unless we switch to one-thread-per-subprocess 

> Should I open two separate tickets for each one of these issue
> eventhough the cause is the same, i.e. ~QProcess always calling
> waitForFinished() so long as "d->processState != NoRunning" ?

No. I thought you meant two different sources.

> Please note that were it not for VLC blocking of the SIGCHLD signal, I
> doubt I would have noticed this issue because the condition under
> which waitForFinished is called in QProcess' dtor above would probably
> never be met ??

Right. I'm guessing that there is no bug in the code if the SIGCHLD handler is 

Thiago Macieira - thiago (AT) - thiago (AT)
  Senior Product Manager - Nokia, Qt Development Frameworks
      PGP/GPG: 0x6EF45358; fingerprint:
      E067 918B B660 DBD1 105C  966C 33F5 F005 6EF4 5358
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 190 bytes
Desc: This is a digitally signed message part.
URL: <>

More information about the kde-core-devel mailing list