[erlang-questions] eaddrinuse despite {reuseaddr, true}

[JD Bothma]

On 5 September 2013 09:58, aman mangal <mangalaman93@REDACTED> wrote:

>
> The error is thrown in the first line. It is returning *{error, **
> eaddrinuse}*  (where you are expeciting *{ok, LSock}*) because the port
> is already being used by some different process. Two process cannot listen
> on the same port at a time.
>

 It runs for a while, and sometimes gets through all bind/closes, but
sometimes crashes mid-way.

reuseaddr should be telling the OS that the closing socket may be reused
when this process tries to listen on the same port again.

No process was listening on this port before the test. This code should be
ensuring that the OS allows listening on the socket even when the last
close hasn't completely released the socket. Without reuseaddr, we can
sometimes expect eaddrinuse because close returns before the socket is
guaranteed to be completely released.

That's if I haven't misunderstood something. If this code is correct,
either something's happening on my machines that I'm not controlling
properly or there's a synchronisation bug in the erlang networking code
that I'd like to help identify and solve.


> On Thu, Sep 5, 2013 at 1:16 PM, JD Bothma <jbothma@REDACTED> wrote:
>
>> Why can this sometimes exit with exception error: no match of right hand
>> side value {error,eaddrinuse} ?
>>
>> As far as I know, nothing's connecting to the socket in this time.
>>
>> [ begin {ok, LSock} = gen_tcp:listen(12345, [{reuseaddr, true}]),
>>            {error, timeout} = gen_tcp:accept(LSock, 0),
>>            ok = gen_tcp:close(LSock)
>>    end
>>   || _X <- lists:seq(1, 100000) ].
>>
>> This is on R14 and 15 on linux and R16 on OS X.
>>
>> BTW it doesn't seem to happen if I don't accept. I'm debugging this
>> behaviour in yaws with SSL but it also seems to happen with plain gen_tcp.
>>
>> JD
>>
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>>
>
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