diff options
Diffstat (limited to 'libgo/go/runtime/debug/garbage_test.go')
| -rw-r--r-- | libgo/go/runtime/debug/garbage_test.go | 68 |
1 files changed, 66 insertions, 2 deletions
diff --git a/libgo/go/runtime/debug/garbage_test.go b/libgo/go/runtime/debug/garbage_test.go index 04e954b1b1e..62eeb2c8078 100644 --- a/libgo/go/runtime/debug/garbage_test.go +++ b/libgo/go/runtime/debug/garbage_test.go @@ -5,6 +5,7 @@ package debug_test import ( + "internal/testenv" "runtime" . "runtime/debug" "testing" @@ -104,15 +105,78 @@ func TestFreeOSMemory(t *testing.T) { } } +var ( + setGCPercentBallast interface{} + setGCPercentSink interface{} +) + func TestSetGCPercent(t *testing.T) { + testenv.SkipFlaky(t, 20076) + // Test that the variable is being set and returned correctly. - // Assume the percentage itself is implemented fine during GC, - // which is harder to test. old := SetGCPercent(123) new := SetGCPercent(old) if new != 123 { t.Errorf("SetGCPercent(123); SetGCPercent(x) = %d, want 123", new) } + + // Test that the percentage is implemented correctly. + defer func() { + SetGCPercent(old) + setGCPercentBallast, setGCPercentSink = nil, nil + }() + SetGCPercent(100) + runtime.GC() + // Create 100 MB of live heap as a baseline. + const baseline = 100 << 20 + var ms runtime.MemStats + runtime.ReadMemStats(&ms) + setGCPercentBallast = make([]byte, baseline-ms.Alloc) + runtime.GC() + runtime.ReadMemStats(&ms) + if abs64(baseline-int64(ms.Alloc)) > 10<<20 { + t.Fatalf("failed to set up baseline live heap; got %d MB, want %d MB", ms.Alloc>>20, baseline>>20) + } + // NextGC should be ~200 MB. + const thresh = 20 << 20 // TODO: Figure out why this is so noisy on some builders + if want := int64(2 * baseline); abs64(want-int64(ms.NextGC)) > thresh { + t.Errorf("NextGC = %d MB, want %d±%d MB", ms.NextGC>>20, want>>20, thresh>>20) + } + // Create some garbage, but not enough to trigger another GC. + for i := 0; float64(i) < 1.2*baseline; i += 1 << 10 { + setGCPercentSink = make([]byte, 1<<10) + } + setGCPercentSink = nil + // Adjust GOGC to 50. NextGC should be ~150 MB. + SetGCPercent(50) + runtime.ReadMemStats(&ms) + if want := int64(1.5 * baseline); abs64(want-int64(ms.NextGC)) > thresh { + t.Errorf("NextGC = %d MB, want %d±%d MB", ms.NextGC>>20, want>>20, thresh>>20) + } + + // Trigger a GC and get back to 100 MB live with GOGC=100. + SetGCPercent(100) + runtime.GC() + // Raise live to 120 MB. + setGCPercentSink = make([]byte, int(0.2*baseline)) + // Lower GOGC to 10. This must force a GC. + runtime.ReadMemStats(&ms) + ngc1 := ms.NumGC + SetGCPercent(10) + // It may require an allocation to actually force the GC. + setGCPercentSink = make([]byte, 1<<20) + runtime.ReadMemStats(&ms) + ngc2 := ms.NumGC + if ngc1 == ngc2 { + t.Errorf("expected GC to run but it did not") + } +} + +func abs64(a int64) int64 { + if a < 0 { + return -a + } + return a } func TestSetMaxThreadsOvf(t *testing.T) { |