connect() returns EADDRINUSE during massive host->host conn rate

Daniel Eischen deischen at
Wed Nov 28 11:16:29 PST 2007

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?


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