On Thu, Oct 22, 2015 at 03:23:49PM +0200, Jiri Denemark wrote:
On Thu, Oct 22, 2015 at 13:52:29 +0100, Daniel P. Berrange wrote: ...
On a related topic, we don't have great error reporting in the (usually unlikely) scenario that we get a stuck job / timeout. I've long thought it could be desirable to record some metadata when we start jobs, such as the __FUNC__ of the method which started the job, so when we report an error we can include that info as a diagnostic aid.
Do you mean something like
virsh # resume cd error: Failed to resume domain cd error: Timed out during operation: cannot acquire state change lock (held by remoteDispatchDomainSuspend)
This was implemented by v1.2.13-295-gb79f25e
This would have to be against the qemuDomainObjPrivPtr struct. THis makes me think that using the separate bool inJob/inMonitor stack variables is not required.
We could just add
int threadid; bool inJob; bool inMonitor; const char *jobfunc;
to qemuDomainObjPrivPtr. That way you don't need to modify the Enter/Exit functions to add extra arguments - we just track everything internally. When exiting, we'd compare against the threadid, to make sure we don't accidentally relaase a different thread's job.
Yeah, as long as we can make sure threadid is unique and stable:
/* These next two functions are for debugging only, since they are not * guaranteed to give unique values for distinct threads on all * architectures, nor are the two functions guaranteed to give the same * value for the same thread. */ unsigned long long virThreadSelfID(void); unsigned long long virThreadID(virThreadPtr thread);
so far we avoided using thread IDs for anything critical.
So technically that comment is correct, since we're casting the pthread_t type to an unsigned long long, also you cannot directly compare pthread_t == pthread_t. POSIX does however provide pthread_equal() to allow you to compare whether 2 pthread_t values point to the same thread. http://man7.org/linux/man-pages/man3/pthread_self.3.html http://man7.org/linux/man-pages/man3/pthread_equal.3.html Regards, 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 :|