* Daniel P. Berrangé (berra...@redhat.com) wrote: > On Fri, Nov 26, 2021 at 04:31:53PM +0100, Li Zhang wrote: > > When doing live migration with multifd channels 8, 16 or larger number, > > the guest hangs in the presence of the network errors such as missing TCP > > ACKs. > > > > At sender's side: > > The main thread is blocked on qemu_thread_join, migration_fd_cleanup > > is called because one thread fails on qio_channel_write_all when > > the network problem happens and other send threads are blocked on sendmsg. > > They could not be terminated. So the main thread is blocked on > > qemu_thread_join > > to wait for the threads terminated. > > Isn't the right answer here to ensure we've called 'shutdown' on > all the FDs, so that the threads get kicked out of sendmsg, before > trying to join the thread ?
I agree a timeout is wrong here; there is no way to get a good timeout value. However, I'm a bit confused - we should be able to try a shutdown on the receive side using the 'yank' command. - that's what it's there for; Li does this solve your problem? multifd_load_cleanup already kicks sem_sync before trying to do a thread_join - so have we managed to trigger that on the receive side? Dave > > Regards, > Daniel > -- > |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| > |: https://libvirt.org -o- https://fstop138.berrange.com :| > |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :| > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
