Interesting, we are not seeing them go to sleep, simply by looking at the
results we see them continue.
Ill take a look and create a sample, but it was a pretty straight forward
qrocess->start() after setup type call.
Scott
-----Original Message-----
From: Thiago Macieira <thiago.macie...@intel.com>
Sent: Thursday, February 10, 2022 5:58 PM
To: interest@qt-project.org
Cc: Scott Bloom <sc...@towel42.com>
Subject: Re: [Interest] QProcess when ^Z is called
On Thursday, 10 February 2022 16:41:48 PST Scott Bloom wrote:
> I have an issue, that if the customer hits Ctrl-Z after the executable
> is running, but has spawned a subprocess via QProcess, when the system
> is restarted (either in the background or foreground), the QProcess
> finished signal is lost.
>
> Im assuming the OS level signal of sleep/wake cant be monitored while
> the application is a sleep.
>
> Is there any known solution to this?
This goes into an area of process support I have yet to completely understand:
controlling terminals, process groups and session leaders. Ctrl+Z indicates
you're running from the shell, with job control active, which probably means
your Qt process is the session leader. Ctrl+Z would have suspended all
processes in the group. See:
$ (sleep 10s & read)
^Z
[1] + 400272 suspended ( sleep 10s & read; ) ... wait more than 10 seconds ...
$ ps ft$TTY
PID TTY STAT TIME COMMAND
33201 pts/7 Ss 0:02 /bin/zsh
400272 pts/7 T 0:00 \_ /bin/zsh
400273 pts/7 T 0:00 | \_ sleep 10s
400338 pts/7 R+ 0:00 \_ ps ft/dev/pts/7
That means the child process can't exit with just what you described, because
the child is stopped alongside everything else in that process group. There's
something more to your problem that you need to describe.
In any case, a dead child should become a zombie until the parent process
performs the wait() call on it. This is what happens if you continue the
child:
$ killall -CONT sleep
$ ps ft$TTY
PID TTY STAT TIME COMMAND
33201 pts/7 Ss 0:02 /bin/zsh
400394 pts/7 T 0:00 \_ /bin/zsh
400395 pts/7 Z 0:00 | \_ [sleep] <defunct>
400412 pts/7 R+ 0:00 \_ ps ft/dev/pts/7
The parent process will receive the SIGCHLD and QProcess will emit finished()
when it resumes.
--
Thiago Macieira - thiago.macieira (AT) intel.com
Software Architect - Intel DPG Cloud Engineering
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