From ac771df2d89c42f3e55bd07418c33f15256e5899 Mon Sep 17 00:00:00 2001
From: D3Hunter <jujj603@gmail.com>
Date: Fri, 5 Jan 2024 13:47:17 +0800
Subject: [PATCH] lightning: remove alter table lock (#50074)

close pingcap/tidb#50105
---
 br/pkg/lightning/importer/import.go       | 7 +++----
 br/pkg/lightning/importer/table_import.go | 2 --
 2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/br/pkg/lightning/importer/import.go b/br/pkg/lightning/importer/import.go
index 75acf5235be49..26b07acaadf43 100644
--- a/br/pkg/lightning/importer/import.go
+++ b/br/pkg/lightning/importer/import.go
@@ -206,10 +206,9 @@ type Controller struct {
 	db            *sql.DB
 	pdCli         pd.Client
 
-	alterTableLock sync.Mutex
-	sysVars        map[string]string
-	tls            *common.TLS
-	checkTemplate  Template
+	sysVars       map[string]string
+	tls           *common.TLS
+	checkTemplate Template
 
 	errorSummaries errorSummaries
 
diff --git a/br/pkg/lightning/importer/table_import.go b/br/pkg/lightning/importer/table_import.go
index 6bb8cc42c03a8..469f1360cec06 100644
--- a/br/pkg/lightning/importer/table_import.go
+++ b/br/pkg/lightning/importer/table_import.go
@@ -951,7 +951,6 @@ func (tr *TableImporter) postProcess(
 
 	// alter table set auto_increment
 	if cp.Status < checkpoints.CheckpointStatusAlteredAutoInc {
-		rc.alterTableLock.Lock()
 		tblInfo := tr.tableInfo.Core
 		var err error
 		if tblInfo.ContainsAutoRandomBits() {
@@ -976,7 +975,6 @@ func (tr *TableImporter) postProcess(
 				err = common.RebaseGlobalAutoID(ctx, adjustIDBase(newBase), tr, tr.dbInfo.ID, tr.tableInfo.Core)
 			}
 		}
-		rc.alterTableLock.Unlock()
 		saveCpErr := rc.saveStatusCheckpoint(ctx, tr.tableName, checkpoints.WholeTableEngineID, err, checkpoints.CheckpointStatusAlteredAutoInc)
 		if err = firstErr(err, saveCpErr); err != nil {
 			return false, errors.Trace(err)