View Full Version : QProcess won’t terminate immediately in a forked process

9th February 2013, 13:10
I have the following problem:

I have a linux application, which can be either run as a standalone application or a service (forked).

My application later starts another application (in this case, mplayer) using a QProcess.
If I terminate my application, I first sent a SIGTERM to my sub process, wait for its termination and then delete my QProcess object and terminate my application. All this works fine, if I am in standalone mode.

If I do the same in service mode, the QProcess will NOT terminate after I sent the SIGTERM, but the started process gots zombie.
The result is that my application waits 30 seconds (even, if I do NOT add a “waitForFinished”) until it kills the QProcess and terminates.

My question now is:
does anyone know, WHY QProcess cannot be terminated/killed, if the application is running in service mode, but can, if it is running normally?

Thx for any help!!

Some details:
Service mode means:

// start player as daemon
pid_t pid, sid;
// fork off parent process
pid = fork();
if (pid < 0) {
// fork failed
fprintf(stderr, "Unable to fork daemon process.");
if (pid > 0) {
// fork succeeded. terminate parent
qDebug() << "Forking child (" << pid << ") succeeded. Terminating parent (" << getpid() << ").\n";

// child continues...
// start new session
sid = setsid();
if (sid < 0) {
fprintf(stderr, "Unable to start new session.");

my QProcess is started:

this->activePlayer = new QProcess(this);
this->activePlayer->start(QString("mplayer"), this->playerArgs);

and terminated

kill(this->activePlayer->pid(), SIGTERM);
system("killall mplayer 2> /dev/null"); // kill all remaining videoplayer processes!
delete this->activePlayer;

Instead of “kill”, I also tried here



same results! :-(

9th February 2013, 13:28
same results! :-(
What results? It seems to me your process should end by itself.