runtime: bound sudog cache

The unbounded list-based sudog cache can grow infinitely.
This can happen if a goroutine is routinely blocked on one P
and then unblocked and scheduled on another P.
The scenario was reported on golang-nuts list.

We've been here several times. Any unbounded local caches
are bad and grow to infinite size. This change introduces
central sudog cache; local caches become fixed-size
with the only purpose of amortizing accesses to the
central cache.

The change required to move sudog cache from mcache to P,
because mcache is not scanned by GC.

Change-Id: I3bb7b14710354c026dcba28b3d3c8936a8db4e90
Reviewed-on: https://go-review.googlesource.com/3742
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
This commit is contained in:
Dmitry Vyukov 2015-02-03 00:33:02 +03:00
parent 60b8908588
commit 5ef145c809
5 changed files with 72 additions and 29 deletions

View file

@ -24,8 +24,6 @@ type mcache struct {
stackcache [_NumStackOrders]stackfreelist
sudogcache *sudog
// Local allocator stats, flushed during GC.
local_nlookup uintptr // number of pointer lookups
local_largefree uintptr // bytes freed for large objects (>maxsmallsize)