os/exec: constrain thread usage in leaked descriptor test on illumos
On illumos systems, libc can under some conditions make use of files
from /proc. In the case of this test, the creation of new threads was
(in the target thread) causing libc to open and close
"/proc/self/lwp/5/lwpname" to set the thread name, which raced with the
leaking descriptor check (see detailed analysis in #42431).
This change requests that the Go runtime use less threads in the child
process used to check for leaked descriptors, without just disabling the
test. After a thousand repeated trials, the test no longer fails on
illumos.
Fixes #42431.
Change-Id: Iefda26134fc91f7cb205754676e9845d9b7205cc
Reviewed-on: https://go-review.googlesource.com/c/go/+/273966 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
Trust: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>