From d1cae6358ccf27bc2c864b09aad49fd8a67ac264 Mon Sep 17 00:00:00 2001 From: Austin Clements Date: Thu, 23 Apr 2015 20:00:10 -0400 Subject: [PATCH] runtime: fix check for pending GC work When findRunnable considers running a fractional mark worker, it first checks if there's any work to be done; if there isn't there's no point in running the worker because it will just reschedule immediately. However, currently findRunnable just checks work.full and work.partial, whereas getfull can *also* draw work from m.currentwbuf. As a result, findRunnable may not start a worker even though there actually is work. This problem manifests itself in occasional failures of the test/init1.go test. This test is unusual because it performs a large amount of allocation without executing any write barriers, which means there's nothing to force the pointers in currentwbuf out to the work.partial/full lists where findRunnable can see them. This change fixes this problem by making findRunnable also check for a currentwbuf. This aligns findRunnable with trygetfull's notion of whether or not there's work. Change-Id: Ic76d22b7b5d040bc4f58a6b5975e9217650e66c4 Reviewed-on: https://go-review.googlesource.com/9299 Reviewed-by: Russ Cox --- src/runtime/mgc.go | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/runtime/mgc.go b/src/runtime/mgc.go index 497c20f0ea..353610d50c 100644 --- a/src/runtime/mgc.go +++ b/src/runtime/mgc.go @@ -501,7 +501,7 @@ func (c *gcControllerState) findRunnable(_p_ *p) *g { // else for a while, so kick everything out of its run // queue. } else { - if work.full == 0 && work.partial == 0 { + if _p_.m.ptr().currentwbuf == 0 && work.full == 0 && work.partial == 0 { // No work to be done right now. This can // happen at the end of the mark phase when // there are still assists tapering off. Don't -- 2.50.0