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

[Khitai Pang]

On 2017/5/28 01:45, Michael Truog wrote:
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.

Thank you for your explanation, but I don't really understand, if the cause is that the Erlang VM certainly disappeared, how come the connected process got the {EXIT,#Port<0....>,einval} message?

Anyway, what to do to avoid this issue?

Thanks
Khitai

Best Regards,
Michael

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://erlang.org/pipermail/erlang-questions/attachments/20170527/b45f6016/attachment.htm>