[erlang-questions] phantom ports in erlang:ports()

Valentin Micic valentin@REDACTED
Fri Nov 16 07:29:21 CET 2012

I am wondering if this may be attributed to CLOSE_WAIT/TIME_WAIT states sockets may be in during the connection shutdown?
By the some token, if the server in question has a higher frequency of short-lived connections,  this may also explain discrepancy between number of file descriptors as reported by lsof and number of active ports reported by emulator.

Just speculating, of course.


On 13 Nov 2012, at 1:35 PM, Tim Watson wrote:

> Hi guys - can anyone answer this (below) please?
> Begin forwarded message:
>> From: Matthias Radestock <matthias@REDACTED>
>> Subject: phantom ports in erlang:ports()
>> Date: 12 November 2012 18:37:47 GMT
>> To: erlang-questions@REDACTED
>> I've got a customer system, running R15B02, which encountered system_limit errors when accepting tcp connections.
>> 'lsof' indicates that there are just a few hundred file descriptors in use. However, erlang:ports() returns 1010 entries. For the majority of these ports:
>> - erlang:port_info(Port) returns 'undefined'
>> - port_close(Port) fails with 'badarg'
>> - exit(Port, die) doesn't make them go away
>> These ports have been in that state for days.
>> Does anybody have any clue what's going on here?
>> Is there any way to find out more about these ports? Looks like ctrl-c'ing in the emulator shell would allow me to get more info with the 'o' option. Unfortunately the customer's emulator is running detached, so that won't work.
>> Regards,
>> Matthias.
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