On Mon, Feb 14, 2011 at 12:32:18PM +0000, Daniel P. Berrange wrote:
I'm getting periodic failures of the 'commandtest' case where the diff is
DAEMON:no -- < DAEMON:yes
For test cases 'test3' through to 'test15', except 'test'4. Tests 1, 2, 4, 16, 17, 18 are all unaffected. I can never reproduce it when I run just that one test case manually, but the automated builds I'm doing hit it > 50% of the time so it is clearly some kind of race condition. The line of code that's getting confused is this
fprintf(log, "DAEMON:%s\n", getpgrp() == getsid(0) ? "yes" : "no");
but I'm not clear how this can be going wrong. Ideas ?
Hmm, this seems to occur when you run the build under cron. Under an interactive shell getpgrp() != getsid() by default. Under non-interactive shell, then getpgrp() == getsid() even if we didn't ask to daemonize. So this approach to detecting whether we're daemonized isn't reliable. Perhaps the 'commandtest' program itself needs to call setsid()+setpgid() before running the child processes ? Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|