cherry pick pingcap#30290 to release-5.1

Signed-off-by: ti-srebot <ti-srebot@pingcap.com>

executor/builder.go

@@ -86,9 +86,18 @@ type executorBuilder struct {
 	err              error // err is set when there is error happened during Executor building process.
 	hasLock          bool
 	Ti               *TelemetryInfo
+<<<<<<< HEAD
 	// ExplicitStaleness means whether the 'SELECT' clause are using 'AS OF TIMESTAMP' to perform stale read explicitly.
 	explicitStaleness bool
 	txnScope          string
+=======
+	// isStaleness means whether this statement use stale read.
+	isStaleness      bool
+	readReplicaScope string
+	inUpdateStmt     bool
+	inDeleteStmt     bool
+	inInsertStmt     bool
+>>>>>>> 4fbbd5a77... executor: make projection executor unparallel for insert/update/delete (#30290)
 }
 
 // CTEStorages stores resTbl and iterInTbl for CTEExec.
@@ -781,6 +790,7 @@ func (b *executorBuilder) buildSetConfig(v *plannercore.SetConfig) Executor {
 }
 
 func (b *executorBuilder) buildInsert(v *plannercore.Insert) Executor {
+	b.inInsertStmt = true
 	if v.SelectPlan != nil {
 		// Try to update the forUpdateTS for insert/replace into select statements.
 		// Set the selectPlan parameter to nil to make it always update the forUpdateTS.
@@ -1388,6 +1398,12 @@ func (b *executorBuilder) buildProjection(v *plannercore.PhysicalProjection) Exe
 	if int64(v.StatsCount()) < int64(b.ctx.GetSessionVars().MaxChunkSize) {
 		e.numWorkers = 0
 	}
+
+	// Use un-parallel projection for query that write on memdb to avoid data race.
+	// See also https://github.com/pingcap/tidb/issues/26832
+	if b.inUpdateStmt || b.inDeleteStmt || b.inInsertStmt || b.hasLock {
+		e.numWorkers = 0
+	}
 	return e
 }
 
@@ -1861,6 +1877,7 @@ func (b *executorBuilder) buildSplitRegion(v *plannercore.SplitRegion) Executor
 }
 
 func (b *executorBuilder) buildUpdate(v *plannercore.Update) Executor {
+	b.inUpdateStmt = true
 	tblID2table := make(map[int64]table.Table, len(v.TblColPosInfos))
 	multiUpdateOnSameTable := make(map[int64]bool)
 	for _, info := range v.TblColPosInfos {
@@ -1932,6 +1949,7 @@ func getAssignFlag(ctx sessionctx.Context, v *plannercore.Update, schemaLen int)
 }
 
 func (b *executorBuilder) buildDelete(v *plannercore.Delete) Executor {
+	b.inDeleteStmt = true
 	tblID2table := make(map[int64]table.Table, len(v.TblColPosInfos))
 	for _, info := range v.TblColPosInfos {
 		tblID2table[info.TblID], _ = b.is.TableByID(info.TblID)