From patchwork Thu Nov 17 13:20:02 2016
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Subject: [4,of,4] worker: discard waited pid by anyone who noticed it first
From: Yuya Nishihara <yuya@tcha.org>
X-Patchwork-Id: 17615
Message-Id: <5e9721975f8cda7daea6.1479388802@mimosa>
To: mercurial-devel@mercurial-scm.org
Date: Thu, 17 Nov 2016 22:20:02 +0900

# HG changeset patch
# User Yuya Nishihara <yuya@tcha.org>
# Date 1479383829 -32400
#      Thu Nov 17 20:57:09 2016 +0900
# Node ID 5e9721975f8cda7daea6ee0cc6aaad7af5096a08
# Parent  4be342413ddecd0eb6d76c4e5d8bb38fee28061d
worker: discard waited pid by anyone who noticed it first

This makes sure all waited pids are removed before calling killworkers()
even if waitpid()-pids.discard() sequence is interrupted by another SIGCHLD.

diff --git a/mercurial/worker.py b/mercurial/worker.py
--- a/mercurial/worker.py
+++ b/mercurial/worker.py
@@ -111,11 +111,14 @@ def _posixworker(ui, func, staticargs, a
                     if e.errno == errno.EINTR:
                         continue
                     elif e.errno == errno.ECHILD:
-                        break # ignore ECHILD
+                        # child would already be reaped, but pids yet been
+                        # updated (maybe interrupted just after waitpid)
+                        pids.discard(pid)
+                        break
                     else:
                         raise
             if p:
-                pids.remove(p)
+                pids.discard(p)
                 st = _exitstatus(st)
             if st and not problem[0]:
                 problem[0] = st