Restart QProcess

[saaleb]

Hi,

I need to launch a number of external programs from QT application and monitor their state, in case of crashing program need to be restarted. (Linux platform only)
So I found QProcess most useful for this, but have a problem - when I get onError signal from QProcess instance, I can't re-run it with the same parameters, as process still in QProcess::Running state.

I will be very thankful for any advice regarding QProcess re-run thick or may be any more useful way to manage processes

[mcosta]

Hi,

once you received error signal with Crashed value, you can call kill() and then re-run it

[saaleb]

[quote author="mcosta" date="1364211388"]Hi,

once you received error signal with Crashed value, you can call kill() and then re-run it
[/quote]

It's not work.

Even after kill() or terminate() QProcess state equals to QProcess::Running and trying to
call start() will give you:
QProcess::start: Process is already running

I don't know, may be I'm using QProcess wrong, but it looks like a bug. Sending SIGTERM or SIGINT to external process raise only onError() signal, but state of QProcess leaves as running.
I tried to extend QProcess with my own class and set NotRunning state manually(I know thats not correct, just for test), but QProcess also give me warning message.

[mcosta]

Strange,

when you receive error() signal, what is the error value?
Are you sure is "Crashed"??

Can you post you code please?

[saaleb]

Looks like I found a root cause of issue. The reason is a delayed state change after kill, looks like it need to spend some main loop cycles for make QProcess object state actually changed.

Thanks for helping, it just need a fresh head! )

[mcosta]

Hi, you can use QProcess::waitForFinished() for this purpose or catch finished() signal

[J.Fu]

use this:

if(normalAppProcess.state() == QProcess::NotRunning)
{
normalAppProcess.start("address to your app");
}