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From:Dan Nelson Date:June 28 1999 11:02pm
Subject:Re: mysqld (3.22.23b) dumps core (segmentation violation) under h igh load after upgrading to FreeBSD 3.2
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In the last episode (Jun 28), tcobb@stripped said:
> > > We've recently been seeing this on other FreeBSD 3.2 systems,
> > > also. After tracking it down for a while, it is definitely a
> > > problem in the FreeBSD 3.2 libc_r.so, and namely appears to be
> > > caused by some changes in thread priority handling in that
> > > library between 3.1 and 3.2.
> >   
> >   So this is FreeBSD bug?  Have you notified them about it?
> 
> Yes, it appears to be a FreeBSD bug.  We just discovered it last
> Friday, so I have not yet notified them of it.  It is rather
> difficult to reproduce except under quite heavy load.

There was a mega-update to libc_r in the 4.0-current tree on the 20th;
if you can, see if you can build a 4.0 version of libc_r and see
whether that helps mysql or not.  I'm sure the patches will filter back
to the 3.0 tree eventually, but until then...

  Here's a couple of the changes related to thread scheduling and
  mutexes:

  o Temporarily set the state of a thread to PS_SUSPENDED when it
    is first created and placed in the list of threads so that it
    will not be accidentally scheduled before becoming a member
    of one of the scheduling queues.
  o Close a race condition in uthread_close.  (Tor Egge)
  o Protect the scheduling queues while modifying them in
    pthread_cond_signal and _thread_fd_unlock.  (Tor Egge)
  o Ensure that when a thread gets a mutex, the mutex is on that
    threads list of owned mutexes.  (Tor Egge)
  o Set the kernel-in-scheduler flag in _thread_kern_sched_state
    and _thread_kern_sched_state_unlock to prevent a scheduling
    signal from calling the scheduler again.  (Tor Egge)

	-Dan Nelson
	dnelson@stripped
Thread
RE: Re[2]: mysqld (3.22.23b) dumps core (segmentation violation) under h igh load after upgrading to FreeBSD 3.2tcobb28 Jun
  • Re: mysqld (3.22.23b) dumps core (segmentation violation) under h igh load after upgrading to FreeBSD 3.2Dan Nelson29 Jun