On Fri, Jul 13, 2018 at 08:40:19AM +0200, Paolo Bonzini wrote: > On 12/07/2018 18:30, Stefan Hajnoczi wrote: > > On Wed, Jul 11, 2018 at 03:33:21PM +0200, Cornelia Huck wrote: > >> The other qemu-nbds (the inet and the unix socket ones from the first > >> run, the second inet one from the second run) have a single thread with > >> the same backtrace I posted above. > > > > We just discussed this on IRC, but for the record: > > > > qemu-nbd --fork will fork the process after the simpletrace write-out > > thread has been spawned. The child process lacks this thread (due to > > how fork(2) handles multithreading). Either qemu-nbd needs to > > initialize tracing later (but that means we cannot trace early init) or > > simpletrace needs a way to respawn the write-out thread. > > You can use pthread_atfork for this.
Thanks. The man page says: The intent of pthread_atfork() was to provide a mechanism whereby the application (or a library) could ensure that mutexes and other process and thread state would be restored to a consistent state. In practice, this task is generally too difficult to be practicable. Challenge accepted! Stefan
signature.asc
Description: PGP signature
