[erlang-questions] Strange interaction between Docker and Erlangs ports (exit_status lost)

[André Cruz]

Hello.

First of all, thank you for your work!

> On 17 Dec 2015, at 16:51, Lukas Larsson <garazdawi@REDACTED> wrote:
> 
> the questions is what is this child 24 that dies with status 10? It seems to be sticking together with inet_gethost, but I don't understand why it should generate extra SIGCHLDs.

I used this tool on the docker host: http://users.suse.com/~krahmer/exec-notify.c

And the output is:

FORK:parent(pid,tgid)=11154,11130	child(pid,tgid)=11157,11157	[/usr/local/lib/erlang/erts-7.1/bin/beam.smp -- -root /usr/local/lib/erlang -progname erl -- -home /root -- -noshell -s test run -s init stop ]
EXEC:pid=11157,tgid=11157	[Uid:	0	0	0	0]	[/usr/local/lib/erlang/erts-7.1/bin/child_setup false . exec inet_gethost 4  3:524287 11:1 12:0 - ]
EXEC:pid=11157,tgid=11157	[Uid:	0	0	0	0]	[sh -c exec inet_gethost 4  ]
EXEC:pid=11157,tgid=11157	[Uid:	0	0	0	0]	[inet_gethost 4 ]
FORK:parent(pid,tgid)=11157,11157	child(pid,tgid)=11158,11158	[inet_gethost 4 ]
EXIT:pid=11157,11157	exit code=0
EXIT:pid=11158,11158	exit code=10
FORK:parent(pid,tgid)=11154,11130	child(pid,tgid)=11159,11159	[/usr/local/lib/erlang/erts-7.1/bin/beam.smp -- -root /usr/local/lib/erlang -progname erl -- -home /root -- -noshell -s test run -s init stop ]
EXEC:pid=11159,tgid=11159	[Uid:	0	0	0	0]	[/usr/local/lib/erlang/erts-7.1/bin/child_setup false . exec ls 3:524287 11:1 12:0 - ]
EXEC:pid=11159,tgid=11159	[Uid:	0	0	0	0]	[sh -c exec ls ]
EXEC:pid=11159,tgid=11159	[Uid:	0	0	0	0]	[ls ]
EXIT:pid=11159,11159	exit code=0

I don't yet know why that extra process appears, but it sure seems related to inet_gethost. It appears to fork().

André