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| author | Michael Anthony Knyszek <mknyszek@google.com> | 2020-07-23 20:24:56 +0000 |
|---|---|---|
| committer | Michael Knyszek <mknyszek@google.com> | 2020-10-26 17:25:54 +0000 |
| commit | f5c6875f3228951afa1fcf2ec01c614e0fb7e2dd (patch) | |
| tree | 319fc30ada1b03b23908229d77f6662d2e8cf30d /src/runtime/trace.go | |
| parent | 93d7d1685ee9e9f296e20f6c712796e54602e891 (diff) | |
| download | go-f5c6875f3228951afa1fcf2ec01c614e0fb7e2dd.tar.xz | |
runtime: make next_gc atomically accessed
next_gc is mostly updated only during a STW, but may occasionally be
updated by calls to e.g. debug.SetGCPercent. In this case the update is
supposed to be protected by the heap lock, but in reality it's accessed
by gcController.revise which may be called without the heap lock held
(despite its documentation, which will be updated in a later change).
Change the synchronization policy on next_gc so that it's atomically
accessed when the world is not stopped to aid in making revise safe for
concurrent use.
Change-Id: I79657a72f91563f3241aaeda66e8a7757d399529
Reviewed-on: https://go-review.googlesource.com/c/go/+/246962
Trust: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
Diffstat (limited to 'src/runtime/trace.go')
| -rw-r--r-- | src/runtime/trace.go | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/src/runtime/trace.go b/src/runtime/trace.go index 169b650eb4..d3ecd148be 100644 --- a/src/runtime/trace.go +++ b/src/runtime/trace.go @@ -13,6 +13,7 @@ package runtime import ( + "runtime/internal/atomic" "runtime/internal/sys" "unsafe" ) @@ -1146,11 +1147,11 @@ func traceHeapAlloc() { } func traceNextGC() { - if memstats.next_gc == ^uint64(0) { + if nextGC := atomic.Load64(&memstats.next_gc); nextGC == ^uint64(0) { // Heap-based triggering is disabled. traceEvent(traceEvNextGC, -1, 0) } else { - traceEvent(traceEvNextGC, -1, memstats.next_gc) + traceEvent(traceEvNextGC, -1, nextGC) } } |