*: optimize MemTracker object allocation in point get

executor/executor.go

@@ -1658,12 +1658,13 @@ func ResetContextOfStmt(ctx sessionctx.Context, s ast.StmtNode) (err error) {
 	vars := ctx.GetSessionVars()
 	sc := &stmtctx.StatementContext{
 		TimeZone:      vars.Location(),
-		MemTracker:    memory.NewTracker(memory.LabelForSQLText, vars.MemQuotaQuery),
-		DiskTracker:   disk.NewTracker(memory.LabelForSQLText, -1),
 		TaskID:        stmtctx.AllocateTaskID(),
 		CTEStorageMap: map[int]*CTEStorages{},
 		IsStaleness:   false,
 	}
+
+	sc.InitMemTracker(memory.LabelForSQLText, vars.MemQuotaQuery)
+	sc.InitDiskTracker(memory.LabelForSQLText, -1)
 	sc.MemTracker.AttachToGlobalTracker(GlobalMemoryUsageTracker)
 	globalConfig := config.GetGlobalConfig()
 	if globalConfig.OOMUseTmpStorage && GlobalDiskUsageTracker != nil {

sessionctx/stmtctx/stmtctx.go

@@ -172,6 +172,14 @@ type StatementContext struct {
 	// Map to store all CTE storages of current SQL.
 	// Will clean up at the end of the execution.
 	CTEStorageMap interface{}
+
+	// cache is used to reduce object allocation.
+	cache struct {
+		execdetails.RuntimeStatsColl
+		MemTracker  memory.Tracker
+		DiskTracker disk.Tracker
+		LogOnExceed [2]memory.LogOnExceed
+	}
 }
 
 // StmtHints are SessionVars related sql hints.
@@ -292,6 +300,18 @@ func (sc *StatementContext) GetPlanHint() (string, bool) {
 	return sc.planHint, sc.planHintSet
 }
 
+// InitDiskTracker initializes the sc.DiskTracker, use cache to avoid allocation.
+func (sc *StatementContext) InitDiskTracker(label int, bytesLimit int64) {
+	memory.InitTracker(&sc.cache.DiskTracker, label, bytesLimit, &sc.cache.LogOnExceed[0])
+	sc.DiskTracker = &sc.cache.DiskTracker
+}
+
+// InitMemTracker initializes the sc.MemTracker, use cache to avoid allocation.
+func (sc *StatementContext) InitMemTracker(label int, bytesLimit int64) {
+	memory.InitTracker(&sc.cache.MemTracker, label, bytesLimit, &sc.cache.LogOnExceed[1])
+	sc.MemTracker = &sc.cache.MemTracker
+}
+
 // SetPlanHint sets the hint for the plan.
 func (sc *StatementContext) SetPlanHint(hint string) {
 	sc.planHintSet = true

util/memory/tracker.go

@@ -62,10 +62,26 @@ type Tracker struct {
 	isGlobal      bool  // isGlobal indicates whether this tracker is global tracker
 }
 
-// NewTracker creates a memory tracker.
+// InitTracker initializes a memory tracker.
 //	1. "label" is the label used in the usage string.
 //	2. "bytesLimit <= 0" means no limit.
 // For the common tracker, isGlobal is default as false
+func InitTracker(t *Tracker, label int, bytesLimit int64, action ActionOnExceed) {
+	t.mu.children = nil
+	t.actionMu.actionOnExceed = action
+	t.parMu.parent = nil
+
+	t.label = label
+	t.bytesLimit = bytesLimit
+	t.maxConsumed = 0
+	t.isGlobal = false
+	return
+}
+
+// NewTracker creates a memory tracker.
+//     1. "label" is the label used in the usage string.
+//     2. "bytesLimit <= 0" means no limit.
+// For the common tracker, isGlobal is default as false
 func NewTracker(label int, bytesLimit int64) *Tracker {
 	t := &Tracker{
 		label:      label,