[erlang-questions] Port process exits with status einval while external program still runs

[Michael Truog]

On 05/27/2017 09:21 AM, Khitai Pang wrote:
> On 2017/5/28 00:06, Michael Truog wrote:
>>
>>  On 2017/5/27 23:31, Khitai Pang wrote:
>>>> I have observed a situation where the port process exits with reason
>>>> 'einval' but the external program still runs.  The connected process of
>>>> the port receives {EXIT,#Port<0.3069817>,einval}. What makes a port
>>>> process exit with 'einval' while the external program still runs?
>>
>> Normally that is due to the port source code
>
> Do you mean the source code of the external program?

Yes

>
>> not handling a HUP on the output file descriptor,from poll (POLLHUP) or the equivalent using a different function.
>
> Could you be more specific about this situation?  In what occasions will this happen?
>
> My external program is a python script that uses erlport <https://pypi.python.org/pypi/erlport> to communicate with erlang.

erlport should be getting EPIPE in the source code https://github.com/hdima/erlport/blob/master/priv/python2/erlport/erlproto.py#L106-L110 .  However, that depends on the write function getting called to discover the Erlang VM disappeared.

Best Regards,
Michael
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