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

[Dawit A]

On Fri, Feb 4, 2011 at 11:41 AM, Thiago Macieira <thiago at kde.org> wrote:
> Em sexta-feira, 4 de fevereiro de 2011, às 05:24:26, Dawit A escreveu:
>> > In the meantime, I've been discussing with Rémi about the issue and he's
>> > not budging from his position that libraries shoul
>> >  never use Unix signals. To be
>> > honest, he's right: Unix signals are meant to be used centrally only.
>> > But we need SIGCHLD to be notified that a child exited, so we need a
>> > compromise between apps and libraries.
>>
>> That is especially true for QProcess. It is used in several place
>> within kdelibs. If any of those code paths are hit from an app like
>> VLC, the same issue will manifest itself as well. I am still wondering
>> whether or not the QtCreator freeze I get to this day is somehow
>> related to this issue even though I doubt QtCreator does any signal
>> blocking...
>
> Qt workaround patch.
>
> I will most definitely not add this to 4.7. I will show to other engineers in
> the office and we'll consider 4.8.
>
> http://qt.pastebin.com/U6dF8kzd

BTW, there is one side issue I noticed in QProcess through this whole
process. Why does QProcess not exit immediately if I invoke kill or
terminate or even when it just timed out from waiting for the child
process ? IOW, why wait some more for the child process to exit under
those circumstances ? That is what unnecessarily prolongs or even
doubles the blocking period.