Re: [libvirt] Python stream callback removal

On Tue, Aug 09, 2011 at 10:59:02AM +0100, Daniel P. Berrange wrote: > On Mon, Aug 08, 2011 at 06:04:50PM -0400, Dave Allan wrote: > > I'm trying to write an example serial console implementation in python > > (attached), but I'm having some trouble getting stream events to do > > what I want. The console itself works fine as long as the domain > > stays up, but as soon as the domain shuts down the python script goes > > into a tight loop repeatedly calling the stream event callback. > > Debugging indicates that the stream event callback is being requested > > to be removed, but it never actually is removed which makes me think I > > am not properly releasing some resource, but I was under the > > impression that an error on a stream resulting in the stream aborting > > was supposed to free all the resources for me. Is that not correct? > > No where in your code do you ever invoke eventRemoveCallback. > When the stream is "aborted" this just means that libvirtd > has released server side resource & reported the error back > to the client. You still have to remove your event callbacks > otherwise you'll just be invoked forever. See tools/console.c > for example code doing what you're attempting, but in C. > In particular the places which call virConsoleShutdown. > Your code in Python should basically be a straight conversion > of tools/console.c from C into Python. Thanks, that was the problem; calling remove fixed it. What I'm trying to do is to write a console that does not exit when the domain is down, and the code is now working, at least for a short while. However, I am seeing a strange behavior. After the domain has been powered off twice--regardless of whether the domain was started or stopped when the console program is started--when starting the domain the next time the console hangs and no callbacks are called. I attached to the process with gdb and the backtraces are very different when the process is responsive vs. when it is ok. Any ideas on what's going wrong?