Stowage/go
2
0
Fork 0
mirror of https://github.com/golang/go.git synced 2025-12-08 06:10:04 +00:00
Code Issues Projects Releases Packages Wiki Activity

runtime: document concurrency of mheap.spans

Browse source 
We use lock-free reads from mheap.spans, but the safety of these is
somewhat subtle. Document this.

Change-Id: I928c893232176135308e38bed788d5f84ff11533
Reviewed-on: https://go-review.googlesource.com/54310
Reviewed-by: Rick Hudson <rlh@golang.org>
This commit is contained in:
Austin Clements 2017-08-09 11:19:24 -04:00
parent 6a7c4d69cb
commit 53f2d53450
1 changed files with 6 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

6
src/runtime/mheap.go
View file

@ -56,6 +56,12 @@ type mheap struct {
// Internal pages map to an arbitrary span.
// For pages that have never been allocated, spans entries are nil.
//
// Modifications are protected by mheap.lock. Reads can be
// performed without locking, but ONLY from indexes that are
// known to contain in-use or stack spans. This means there
// must not be a safe-point between establishing that an
// address is live and looking it up in the spans array.
//
// This is backed by a reserved region of the address space so
// it can grow without moving. The memory up to len(spans) is
// mapped. cap(spans) indicates the total reserved memory.