lock up in 6.2 (procs massively stuck in Giant)

[John Baldwin]

On Tuesday 12 May 2009 2:12:27 am pluknet wrote:
> 2009/5/11 John Baldwin <jhb at freebsd.org>:
> > On Monday 04 May 2009 11:41:35 pm pluknet wrote:
> >> 2009/5/1 John Baldwin <jhb at freebsd.org>:
> >> > On Thursday 30 April 2009 2:36:34 am pluknet wrote:
> >> >> Hi folks.
> >> >>
> >> >> Today I got a new locking issue.
> >> >> This is the first time I got it, and it's merely reproduced.
> >> >>
> >> >> The box has lost both remote connection and local access.
> >> >> No SIGINFO output on the local console even.
> >> >> Jumping in ddb> shows the next:
> >> >>
> >> >> 1) first, this is a 8-way web server. No processes on runqueue except 
one
> >> > httpd
> >> >> (i.e. ps shows R in its state):
> >> >
> >> > You need to find who owns Giant and what that thread is doing.  You can
> > try
> >> > using 'show lock Giant' as well as 'show lockchain 11568'.
> >> >
> >>
> >> Hi, John!
> >>
> >> Just reproduced now on another box.
> >> Hmm.. stack of the process owing Giant looks garbled.
> >>
> >> db> show lock Giant
> >>  class: sleep mutex
> >>  name: Giant
> >>  flags: {DEF, RECURSE}
> >>  state: {OWNED, CONTESTED}
> >>  owner: 0xd0d79320 (tid 102754, pid 34594, "httpd")
> >>
> >> db> show lockchain 34594
> >> thread 102754 (pid 34594, httpd) running on CPU 7
> >> db> show lockchain 102754
> >> thread 102754 (pid 34594, httpd) running on CPU 7
> >
> > The thread is running, so we don't know what it's top of stack is and you
> > can't a good stack trace in that case.
> >
> > None of your CPUs are idle, so I don't think you have any sort of 
deadlock.
> > You might have a livelock.
> >
> > --
> > John Baldwin
> >
> 
> I'm curious if it could be caused by heavy load.
> I don't know what it might be definitely,
> as it's non-trivial for me to determine the reason
> of a livelock, and to debug it.
> 
> So I think it may have sense to try 7.x, as there
> has been done much locking work.

It may be worth trying 7.  Also, what is the state of the 'swi7: clock' 
process?

-- 
John Baldwin