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-rw-r--r--src/runtime/metrics_test.go35
-rw-r--r--src/runtime/mgcsweep.go23
2 files changed, 48 insertions, 10 deletions
diff --git a/src/runtime/metrics_test.go b/src/runtime/metrics_test.go
index cfb09a3..55d7dc4 100644
--- a/src/runtime/metrics_test.go
+++ b/src/runtime/metrics_test.go
@@ -761,3 +761,38 @@ func TestCPUMetricsSleep(t *testing.T) {
}
t.Errorf(`time.Sleep did not contribute enough to "idle" class: minimum idle time = %.5fs`, minIdleCPUSeconds)
}
+
+func TestMetricHeapUnusedLargeObjectOverflow(t *testing.T) {
+ // This test makes sure /memory/classes/heap/unused:bytes
+ // doesn't overflow when allocating and deallocating large
+ // objects. It is a regression test for #67019.
+ done := make(chan struct{})
+ var wg sync.WaitGroup
+ wg.Add(1)
+ go func() {
+ defer wg.Done()
+ for {
+ for i := 0; i < 10; i++ {
+ runtime.Escape(make([]byte, 1<<20))
+ }
+ runtime.GC()
+ select {
+ case <-done:
+ return
+ default:
+ }
+ }
+ }()
+ s := []metrics.Sample{
+ {Name: "/memory/classes/heap/unused:bytes"},
+ }
+ for i := 0; i < 1000; i++ {
+ metrics.Read(s)
+ if s[0].Value.Uint64() > 1<<40 {
+ t.Errorf("overflow")
+ break
+ }
+ }
+ done <- struct{}{}
+ wg.Wait()
+}
diff --git a/src/runtime/mgcsweep.go b/src/runtime/mgcsweep.go
index 68f1aae..ce0e8df 100644
--- a/src/runtime/mgcsweep.go
+++ b/src/runtime/mgcsweep.go
@@ -771,6 +771,19 @@ func (sl *sweepLocked) sweep(preserve bool) bool {
if nfreed != 0 {
// Free large object span to heap.
+ // Count the free in the consistent, external stats.
+ //
+ // Do this before freeSpan, which might update heapStats' inHeap
+ // value. If it does so, then metrics that subtract object footprint
+ // from inHeap might overflow. See #67019.
+ stats := memstats.heapStats.acquire()
+ atomic.Xadd64(&stats.largeFreeCount, 1)
+ atomic.Xadd64(&stats.largeFree, int64(size))
+ memstats.heapStats.release()
+
+ // Count the free in the inconsistent, internal stats.
+ gcController.totalFree.Add(int64(size))
+
// NOTE(rsc,dvyukov): The original implementation of efence
// in CL 22060046 used sysFree instead of sysFault, so that
// the operating system would eventually give the memory
@@ -791,16 +804,6 @@ func (sl *sweepLocked) sweep(preserve bool) bool {
} else {
mheap_.freeSpan(s)
}
-
- // Count the free in the consistent, external stats.
- stats := memstats.heapStats.acquire()
- atomic.Xadd64(&stats.largeFreeCount, 1)
- atomic.Xadd64(&stats.largeFree, int64(size))
- memstats.heapStats.release()
-
- // Count the free in the inconsistent, internal stats.
- gcController.totalFree.Add(int64(size))
-
return true
}