os/exec: exec pipes not closed when LookupPath fails

[gopherbot]

by jessevdk:

I was working with spawning a lot of processes that didn't exist from a number of
goroutines. For these processes I was opening pipes for stdin, stdout and stderr. After
some point my process always got errors like "pipe: too many open files".

I quickly went through the sources and it seems that when LookupPath fails, and
cmd.Start is called, the open ends of the pipes associated to the command are not closed
at that time.

Initially I found it hard to reproduce the bug because when the GC gets time to run, it
will call the finalizers of the open files which end up closing the pipes. However, with
enough go routines running at the same time (which I had in my original program) the
problem can be reproduced quite easily.

I've attached a small pipebug.go file which demonstrates the problem.

Attachments:

1. pipebug.go (614 bytes)

[ianlancetaylor]

Comment 1:

Labels changed: added priority-soon, go1.1maybe, removed priority-triage.

[bradfitz]

Comment 2:

Sent https://golang.org/cl/7799046/

Owner changed to @bradfitz.

Status changed to Started.

[bradfitz]

Comment 3:

This issue was closed by revision 9db0583.

Status changed to Fixed.

[gopherbot]

CL https://golang.org/cl/37343 mentions this issue.