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RE: Re: accept() FreeBSD hangs when out of resources
This seems a lot like the problem I've seen - and reported on 17/4-07.
I've been able to occasionally reproduce it manually with a browser
(MSIE), but enabling TCP debug logging causes the problem to go away
(not occur).
AFAICS, it is a race condition in the TCP stack causing socket buffers
to be leaked (forever). Calling cyg_kmem_print_stats() displays the
problem (but you need reset to recover :-() :
Network stack mbuf stats:
mbufs 97, clusters 60, free clusters 1
Failed to get 0 times
Waited to get 0 times
Drained queues to get 0 times
VM zone 'ripcb':
Total: 64, Free: 64, Allocs: 0, Frees: 0, Fails: 0
VM zone 'tcpcb':
Total: 64, Free: 61, Allocs: 353, Frees: 350, Fails: 0
VM zone 'udpcb':
Total: 64, Free: 63, Allocs: 4, Frees: 3, Fails: 0
VM zone 'socket':
Total: 64, *Free: 0*, Allocs: 365, Frees: 293, Fails: 8
Misc mpool: total 98304, free 4192, max free block 3748
Mbufs pool: total 81792, free 69248, blocksize 128
Clust pool: total 163840, free 38912, blocksize 2048
FWIW, I have not had time to dig into this (as my attempts to produce a
test bench has failed...)
---Lars
-----Original Message-----
From: ecos-discuss-owner@ecos.sourceware.org
[mailto:ecos-discuss-owner@ecos.sourceware.org] On Behalf Of Tad
Sent: 12. juni 2007 14:05
To: eCos Disuss
Subject: Re: [ECOS] Re: accept() FreeBSD hangs when out of resources
Andrew Lunn wrote:
> On Mon, Jun 11, 2007 at 04:05:57PM -0800, Tad wrote:
>
>> Andrew Lunn wrote:
>>
>>> On Mon, Jun 11, 2007 at 03:42:07PM -0800, Tad wrote:
>>>
>>>
>>>>>> accept() won't return and won't timeout (>12hrs) when listen()
>>>>>> indicates a new connection, if out of sockets/file-descriptors
and all
>>>>>> TCP connections are in ESTABLISHED state.
>>>>>>
>>>>>>
>>>>> Where exactly is it blocked. Please could you provide a call
stack.
>>>>>
more info.
seems to be dependent on CYGNUM_FILEIO_NFILE rather than
CYGPKG_NET_MAXSOCKETS. reducing NFILE < MAXSOCKETS causes accept to
hang with fewer established connections than before reduction.
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