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Re: [sumo-user] Address already in use: Race condition between isolated executions
Thank you for the clarification

After trying the original test with version 1.8.0, I still receive the same error
(that somewhat differs from the simple test as it is also accompanied by "unpack requires a buffer of 4 bytes" error)

Perhaps the original problem is other than the simple test was reproducing.

See attached log with the noticed behavior.

Is there anything I can try to test what the cause is and make it easily reproducible?

This behavior is happening in a fairly complex application (few parallel simulations created several times) with docker executions on a ubuntu remote server.


Thank you in advance


Sincerely,

Marcelo d'Almeidas

On Fri, Nov 27, 2020 at 1:45 PM Michael Behrisch <oss@xxxxxxxxxxx> wrote:
Hi,
yes it is the intended behavior. We noticed that there is no point in
leaving the port open once all clients have connected. So we just close
it and it is available to be used again. This should also help in
avoiding conflicts since the ports are not open very long.

Best regards,
Michael

Am 26.11.20 um 13:02 schrieb Marcelo Andrade Rodrigues D Almeida:
> Sorry for the very late reply and thank you for working on it
>
> I built it from the source and tested it with the simple example above
>
>
> I was expecting it to leave an exception telling that the address was
> already in use, instead of hanging the process.
>
> The behavior now is that the second connection is successful even though
> the same port was used.
>
> When inspecting the system tcp ports with 'netstat -atn', it seems that
> both are created with a 'double-mapping' (port 50000)
>
> (base) marcelo@Lenovo-Legion-5-15IMH05H:~$ netstat -atn
> Active Internet connections (servers and established)
> Proto Recv-Q Send-Q Local Address           Foreign Address         State
> tcp        0      0 0.0.0.0:34463 <http://0.0.0.0:34463>           
> 0.0.0.0:*               LISTEN
> tcp        0      0 127.0.0.53:53 <http://127.0.0.53:53>           
> 0.0.0.0:*               LISTEN
> tcp        0      0 127.0.0.1:631 <http://127.0.0.1:631>           
> 0.0.0.0:*               LISTEN
> tcp        0      0 127.0.0.1:50000 <http://127.0.0.1:50000>
> 127.0.0.1:45794 <http://127.0.0.1:45794>         ESTABLISHED
> tcp        0      0 192.168.1.5:48216 <http://192.168.1.5:48216>
> 216.58.202.142:443 <http://216.58.202.142:443>      ESTABLISHED
> tcp        0      0 192.168.1.5:55908 <http://192.168.1.5:55908>
> 3.85.152.15:443 <http://3.85.152.15:443>         ESTABLISHED
> tcp        0      0 127.0.0.1:60188 <http://127.0.0.1:60188>
> 127.0.0.1:59996 <http://127.0.0.1:59996>         TIME_WAIT
> tcp        0      0 127.0.0.1:45794 <http://127.0.0.1:45794>
> 127.0.0.1:50000 <http://127.0.0.1:50000>         ESTABLISHED
> tcp        0      0 127.0.0.1:60192 <http://127.0.0.1:60192>
> 127.0.0.1:59996 <http://127.0.0.1:59996>         TIME_WAIT
> tcp        0      0 192.168.1.5:45396 <http://192.168.1.5:45396>
> 75.2.53.94:443 <http://75.2.53.94:443>          ESTABLISHED
> tcp        0      0 192.168.1.5:33528 <http://192.168.1.5:33528>
> 198.252.206.25:443 <http://198.252.206.25:443>      ESTABLISHED
> tcp        0      0 127.0.0.1:43994 <http://127.0.0.1:43994>
> 127.0.0.1:34859 <http://127.0.0.1:34859>         TIME_WAIT
> tcp        0      0 127.0.0.1:50000 <http://127.0.0.1:50000>
> 127.0.0.1:45798 <http://127.0.0.1:45798>         ESTABLISHED
> tcp        0      0 192.168.1.5:48220 <http://192.168.1.5:48220>
> 216.58.202.142:443 <http://216.58.202.142:443>      TIME_WAIT
> tcp        0      0 192.168.1.5:58644 <http://192.168.1.5:58644>
> 3.225.183.105:443 <http://3.225.183.105:443>       ESTABLISHED
> tcp        0      0 192.168.1.5:48502 <http://192.168.1.5:48502>
> 216.58.202.142:443 <http://216.58.202.142:443>      ESTABLISHED
> tcp        0      0 127.0.0.1:56510 <http://127.0.0.1:56510>
> 127.0.0.1:34165 <http://127.0.0.1:34165>         ESTABLISHED
> tcp        0      0 192.168.1.5:43464 <http://192.168.1.5:43464>
> 52.11.85.228:443 <http://52.11.85.228:443>        ESTABLISHED
> tcp        0      0 192.168.1.5:44560 <http://192.168.1.5:44560>
> 172.217.28.74:443 <http://172.217.28.74:443>       ESTABLISHED
> tcp        0      0 192.168.1.5:36802 <http://192.168.1.5:36802>
> 172.217.28.3:443 <http://172.217.28.3:443>        ESTABLISHED
> tcp        0      0 127.0.0.1:45798 <http://127.0.0.1:45798>
> 127.0.0.1:50000 <http://127.0.0.1:50000>         ESTABLISHED
> tcp        0      0 127.0.0.1:34118 <http://127.0.0.1:34118>
> 127.0.0.1:40919 <http://127.0.0.1:40919>         CLOSE_WAIT
> tcp        0      0 192.168.1.5:51196 <http://192.168.1.5:51196>
> 107.21.203.251:443 <http://107.21.203.251:443>      ESTABLISHED
> tcp        0      0 192.168.1.5:36070 <http://192.168.1.5:36070>
> 172.217.192.189:443 <http://172.217.192.189:443>     ESTABLISHED
> tcp        0      0 192.168.1.5:36662 <http://192.168.1.5:36662>
> 34.235.68.102:443 <http://34.235.68.102:443>       TIME_WAIT
> tcp        0      0 192.168.1.5:37930 <http://192.168.1.5:37930>
> 172.217.29.229:443 <http://172.217.29.229:443>      ESTABLISHED
> tcp6       0      0 127.0.0.1:6942 <http://127.0.0.1:6942>          :::*
>                     LISTEN
> tcp6       0      0 127.0.0.1:63342 <http://127.0.0.1:63342>         
> :::*                    LISTEN
> tcp6       0      0 :::80                   :::*                    LISTEN
> tcp6       0      0 :::34165                :::*                    LISTEN
> tcp6       0      0 :::40919                :::*                    LISTEN
> tcp6       0      0 ::1:631                 :::*                    LISTEN
> tcp6       0      0 127.0.0.1:40919 <http://127.0.0.1:40919>
> 127.0.0.1:34118 <http://127.0.0.1:34118>         FIN_WAIT2
> tcp6       0      0 127.0.0.1:34165 <http://127.0.0.1:34165>
> 127.0.0.1:56510 <http://127.0.0.1:56510>         ESTABLISHED
>
>
> Is this the intended behavior?
>
>
> Thank you once again
>
>
> Sincerely,
>
> Marcelo d'Almeida
>
> On Tue, Nov 3, 2020 at 6:10 PM Michael Behrisch <oss@xxxxxxxxxxx
> <mailto:oss@xxxxxxxxxxx>> wrote:
>
>     Hi,
>     you are right, this behavior is not useful. I opened a ticket here:
>     https://github.com/eclipse/sumo/issues/7750
>     <https://github.com/eclipse/sumo/issues/7750>. It already has a
>     preliminary fix but this needs a little more testing. If you like, you
>     can try the nightly build (showing up tomorrow) or build yourself and
>     report your findings.
>
>     Best regards,
>     Michael
>
>     Am 03.11.20 um 18:08 schrieb Marcelo Andrade Rodrigues D Almeida:
>      > Hi everyone
>      >
>      > Trying to open two simulations with the same port hangs the entire
>      > execution, instead of raising an exception
>      >
>      > Error
>      > "Error: tcpip::Socket::accept() Unable to create listening socket:
>      > Address already in use
>      > Quitting (on error)."
>      >
>      >
>      > I'm currently running several experiments, simultaneously, in
>     isolated
>      > docker containers. And inside every experiment, running several
>     parallel
>      > simulations
>      >
>      > The problem is that my experiments can step (and eventually does)
>     into
>      > address conflict problems (race condition) and the hanging
>     prevents any
>      > chance of retrying it with a new port, suspending the entire
>     experiment
>      > forever.
>      >
>      > The use of synchronization locks prevents address conflicts
>     inside one
>      > experiment, so I'm basically limited to run one experiment at a time,
>      > which is very time consuming.
>      >
>      >
>      > As a workaround, I'm going to specify port ranges for each simulation
>      > and check it for availability
>      >
>      > Let me know if there is a better solution as workaround
>      >
>      > And thank you in advance
>      >
>      >
>      > P.S. I've included a trivial example to show the hanging
>     behavior, but
>      > there is nothing special about it.
>      >
>      >
>      > Sincerely,
>      >
>      > Marcelo d'Almeida
>      >
>      > _______________________________________________
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>
>
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