gctuner

Signed-off-by: Weizhen Wang <wangweizhen@pingcap.com>
pingcap · Oct 8, 2022 · 6450604 · 6450604
1 parent 643717c
commit 6450604
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Showing 3 changed files with 13 additions and 10 deletions.
diff --git a/sessionctx/variable/sysvar.go b/sessionctx/variable/sysvar.go
@@ -35,6 +35,7 @@ import (
 	"github.com/pingcap/tidb/sessionctx/stmtctx"
 	"github.com/pingcap/tidb/types"
 	_ "github.com/pingcap/tidb/types/parser_driver" // for parser driver
+	"github.com/pingcap/tidb/util"
 	"github.com/pingcap/tidb/util/collate"
 	"github.com/pingcap/tidb/util/gctuner"
 	"github.com/pingcap/tidb/util/logutil"
@@ -623,6 +624,9 @@ var defaultSysVars = []*SysVar{
 	{Scope: ScopeGlobal, Name: TiDBEnableGOGCTuner, Value: BoolToOnOff(DefTiDBEnableGOGCTuner), Type: TypeBool, SetGlobal: func(s *SessionVars, val string) error {
 		on := TiDBOptOn(val)
 		gctuner.EnableGOGCTuner.Store(on)
+		if !on {
+			util.SetGOGC(int(gctuner.DefaultGCPercent))
+		}
 		return nil
 	}},
 	{Scope: ScopeGlobal, Name: TiDBEnableTelemetry, Value: BoolToOnOff(DefTiDBEnableTelemetry), Type: TypeBool},

diff --git a/util/gctuner/tuner.go b/util/gctuner/tuner.go
@@ -30,14 +30,14 @@ const (
 	MinGCPercent uint32 = 20
 )
 
-var defaultGCPercent uint32 = 100
+var DefaultGCPercent uint32 = 100
 
 // EnableGOGCTuner is to control whether enable the GOGC tuner.
 var EnableGOGCTuner atomic.Bool
 
 func init() {
 	if val, err := strconv.Atoi(os.Getenv("GOGC")); err == nil {
-		defaultGCPercent = uint32(val)
+		DefaultGCPercent = uint32(val)
 	}
 }
 
@@ -49,7 +49,6 @@ func Tuning(threshold uint64) {
 	if threshold <= 0 && globalTuner != nil {
 		globalTuner.stop()
 		globalTuner = nil
-		util.SetGOGC(int(defaultGCPercent))
 		return
 	}
 
@@ -63,7 +62,7 @@ func Tuning(threshold uint64) {
 // GetGOGC returns the current GCPercent.
 func GetGOGC() uint32 {
 	if globalTuner == nil {
-		return defaultGCPercent
+		return DefaultGCPercent
 	}
 	return globalTuner.getGCPercent()
 }
@@ -94,7 +93,7 @@ type tuner struct {
 
 func newTuner(threshold uint64) *tuner {
 	t := &tuner{}
-	t.gcPercent.Store(defaultGCPercent)
+	t.gcPercent.Store(DefaultGCPercent)
 	t.threshold.Store(threshold)
 	t.finalizer = newFinalizer(t.tuning) // start tuning
 	return t
@@ -143,7 +142,7 @@ func (t *tuner) tuning() {
 func calcGCPercent(inuse, threshold uint64) uint32 {
 	// invalid params
 	if inuse == 0 || threshold == 0 {
-		return defaultGCPercent
+		return DefaultGCPercent
 	}
 	// inuse heap larger than threshold, use min percent
 	if threshold <= inuse {

diff --git a/util/gctuner/tuner_test.go b/util/gctuner/tuner_test.go
@@ -29,7 +29,7 @@ func TestTuner(t *testing.T) {
 	threshold := memLimit / 2
 	tn := newTuner(threshold)
 	require.Equal(t, threshold, tn.threshold.Load())
-	require.Equal(t, defaultGCPercent, tn.getGCPercent())
+	require.Equal(t, DefaultGCPercent, tn.getGCPercent())
 
 	// no heap
 	testHeap = make([]byte, 1)
@@ -77,9 +77,9 @@ func TestTuner(t *testing.T) {
 func TestCalcGCPercent(t *testing.T) {
 	const gb = 1024 * 1024 * 1024
 	// use default value when invalid params
-	require.Equal(t, defaultGCPercent, calcGCPercent(0, 0))
-	require.Equal(t, defaultGCPercent, calcGCPercent(0, 1))
-	require.Equal(t, defaultGCPercent, calcGCPercent(1, 0))
+	require.Equal(t, DefaultGCPercent, calcGCPercent(0, 0))
+	require.Equal(t, DefaultGCPercent, calcGCPercent(0, 1))
+	require.Equal(t, DefaultGCPercent, calcGCPercent(1, 0))
 
 	require.Equal(t, MaxGCPercent, calcGCPercent(1, 3*gb))
 	require.Equal(t, MaxGCPercent, calcGCPercent(gb/10, 4*gb))