From owner-freebsd-net@FreeBSD.ORG  Wed Nov 28 19:28:48 2007
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Date: Wed, 28 Nov 2007 14:16:27 -0500 (EST)
From: Daniel Eischen <deischen@freebsd.org>
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To: Ivan Voras <ivoras@freebsd.org>
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Cc: freebsd-net@freebsd.org, freebsd-stable@freebsd.org
Subject: Re: connect() returns EADDRINUSE during massive host->host conn rate
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On Wed, 28 Nov 2007, Ivan Voras wrote:

> Jan Srzednicki wrote:
>> Hello,
>>
>> I have a pair of hosts. One of them performs a massive amount of
>> TCP connections to the other one, all to the same port. This setup
>> mostly works fine, but from time to time (that varies, from once a
>> minute to one a half an hour), the connect(2) syscall fails with
>> EADDRINUSE. The connection rate tops to 50 connection
>> initiations/second.
>
> This looks like the old (and probably well known) problem "ab" has.
> ("ab" is "apache benchmark", a utility which is bundled with apache and
> which does repeated connections to the specified address, does
> transactions and computes some statistics). AFAIK this behaviour was
> present since at least 5.2, maybe earlier. No known fixes.

Could it have anything to do with the listen backlog on the
server end?

-- 
DE