From kde-devel  Sun Aug 10 17:20:52 2003
From: Thiago Macieira <thiagom () wanadoo ! fr>
Date: Sun, 10 Aug 2003 17:20:52 +0000
To: kde-devel
Subject: Re: Waiting for a process to terminate
X-MARC-Message: https://marc.info/?l=kde-devel&m=106053619413073
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Joao Luis Silva Assuncao wrote:
>Hello all,
>I'm using a thread (QThread) to do some heavy job that implies to execute
>multiples times another program. Since it must wait until the process ends
> to execute a new process, I think I can use the signal  processExited to
> know when the process ends, but that implies that the thread must be a
> QObject to receive the signal. I readied in QT documentation and in some
> tutorial about kde and MT that QObject derived classes should not be used
> within threads, so this idea of using signals inside threads is probably
> not a good idea. So how can I execute a process within a thread, waiting
> for it to complete but without blocking my application?

You cannot use signals accross threads. Signals are confined to the main Qt=
=20
event thread.

I recommend that, instead, you start your process from the event thread and=
=20
use the normal signalling mechanisms for the child process's exit. When you=
=20
detect that it's done, you can start another. If you need a thread to proce=
ss=20
some data the child created, start the thread at that moment or, if it's=20
already running, use QWaitCondition or QSemaphore to tell it new data is=20
available.

=2D-=20
  Thiago Macieira  -  Registered Linux user #65028
   thiagom@mail.com          =20
    ICQ UIN: 1967141   PGP/GPG: 0x6EF45358; fingerprint:
    E067 918B B660 DBD1 105C  966C 33F5 F005 6EF4 5358

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