RELENG_7 libthr: _umtx_op -1 errno 60 Operation timed out

[Andriy Gapon]

I observe the following issue with some programs (e.g. firefox) from
time. A completely idle program suddenly starts using a lot of CPU and
sometimes memory too. For example, minimized firefox with no pages open.
Restarting the program make the behavior go away.
On one such occasion I ran ktrace on firefox and I saw a lot of messages
like the following in kdump:
 13974 firefox-bin RET   _umtx_op -1 errno 60 Operation timed out
Attaching with gdb I also saw a quite strange stack (unfortunately
firefox and the libs are without debug). I didn't save it but it looked
something like the following:
__error()
??
??
pthread_cond_init()
??

I wonder what could be a cause of this.
Could it be some sort of resource limitation?

-- 
Andriy Gapon