From: Michael Hudson-Doyle <michael.hudson@canonical.com>
Date: Wed, 6 Apr 2016 23:47:32 +0000 (+1200)
Subject: runtime: clamp OS-reported number of processors to _MaxGomaxprocs
X-Git-Tag: go1.7beta1~846
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=31cf1c17792d4da9dae2504c703633a0db8072c7;p=gostls13.git

runtime: clamp OS-reported number of processors to _MaxGomaxprocs

So that all Go processes do not die on startup on a system with >256 CPUs.

I tested this by hacking osinit to set ncpu to 1000.

Updates #15131

Change-Id: I52e061a0de97be41d684dd8b748fa9087d6f1aef
Reviewed-on: https://go-review.googlesource.com/21599
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
---

diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index 5145c84aea..1f55b0fa21 100644
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -449,6 +449,9 @@ func schedinit() {
 
 	sched.lastpoll = uint64(nanotime())
 	procs := int(ncpu)
+	if procs > _MaxGomaxprocs {
+		procs = _MaxGomaxprocs
+	}
 	if n := atoi(gogetenv("GOMAXPROCS")); n > 0 {
 		if n > _MaxGomaxprocs {
 			n = _MaxGomaxprocs