Date: Tue, 12 May 2009 10:12:27 +0400 From: pluknet <pluknet@gmail.com> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-stable@freebsd.org Subject: Re: lock up in 6.2 (procs massively stuck in Giant) Message-ID: <a31046fc0905112312y2496e5cex334ddcaf57889909@mail.gmail.com> In-Reply-To: <200905110949.31142.jhb@freebsd.org> References: <a31046fc0904292336w17aca317hefd32dad5bc28007@mail.gmail.com> <200905010949.45927.jhb@freebsd.org> <a31046fc0905042041kdfcfa85u38e84db5197c929c@mail.gmail.com> <200905110949.31142.jhb@freebsd.org>
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2009/5/11 John Baldwin <jhb@freebsd.org>:
> On Monday 04 May 2009 11:41:35 pm pluknet wrote:
>> 2009/5/1 John Baldwin <jhb@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.
Thank you.
--
wbr,
pluknet
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