*: make auto-analyze concurrency configurable

executor/adapter.go

@@ -469,8 +469,20 @@ func (a *ExecStmt) Exec(ctx context.Context) (_ sqlexec.RecordSet, err error) {
 		if !ok {
 			oriIso = "REPEATABLE-READ"
 		}
-		terror.Log(sctx.GetSessionVars().SetSystemVar(variable.TiDBBuildStatsConcurrency, "1"))
-		sctx.GetSessionVars().SetDistSQLScanConcurrency(1)
+		autoConcurrency, err1 := sctx.GetSessionVars().GetSessionOrGlobalSystemVar(ctx, variable.TiDBAutoBuildStatsConcurrency)
+		terror.Log(err1)
+		if err1 == nil {
+			terror.Log(sctx.GetSessionVars().SetSystemVar(variable.TiDBBuildStatsConcurrency, autoConcurrency))
+		}
+		sVal, err2 := sctx.GetSessionVars().GetSessionOrGlobalSystemVar(ctx, variable.TiDBSysProcScanConcurrency)
+		terror.Log(err2)
+		if err2 == nil {
+			concurrency, err3 := strconv.ParseInt(sVal, 10, 64)
+			terror.Log(err3)
+			if err3 == nil {
+				sctx.GetSessionVars().SetDistSQLScanConcurrency(int(concurrency))
+			}
+		}
 		sctx.GetSessionVars().SetIndexSerialScanConcurrency(1)
 		terror.Log(sctx.GetSessionVars().SetSystemVar(variable.TxnIsolation, ast.ReadCommitted))
 		defer func() {

sessionctx/variable/sysvar.go

@@ -1122,6 +1122,8 @@ var defaultSysVars = []*SysVar{
 	}, GetGlobal: func(_ context.Context, s *SessionVars) (string, error) {
 		return BoolToOnOff(EnableTmpStorageOnOOM.Load()), nil
 	}},
+	{Scope: ScopeGlobal, Name: TiDBAutoBuildStatsConcurrency, Value: strconv.Itoa(DefTiDBAutoBuildStatsConcurrency), Type: TypeInt, MinValue: 1, MaxValue: MaxConfigurableConcurrency},
+	{Scope: ScopeGlobal, Name: TiDBSysProcScanConcurrency, Value: strconv.Itoa(DefTiDBSysProcScanConcurrency), Type: TypeInt, MinValue: 1, MaxValue: MaxConfigurableConcurrency},
 	{Scope: ScopeGlobal, Name: TiDBMemoryUsageAlarmRatio, Value: strconv.FormatFloat(DefMemoryUsageAlarmRatio, 'f', -1, 64), Type: TypeFloat, MinValue: 0.0, MaxValue: 1.0, SetGlobal: func(_ context.Context, s *SessionVars, val string) error {
 		MemoryUsageAlarmRatio.Store(tidbOptFloat64(val, DefMemoryUsageAlarmRatio))
 		return nil

sessionctx/variable/tidb_vars.go

@@ -849,6 +849,10 @@ const (
 	TiDBDDLEnableFastReorg = "tidb_ddl_enable_fast_reorg"
 	// TiDBDDLDiskQuota used to set disk quota for lightning add index.
 	TiDBDDLDiskQuota = "tidb_ddl_disk_quota"
+	// TiDBAutoBuildStatsConcurrency is used to set the build concurrency of auto-analyze.
+	TiDBAutoBuildStatsConcurrency = "tidb_auto_build_stats_concurrency"
+	// TiDBSysProcScanConcurrency is used to set the scan concurrency of for backend system processes, like auto-analyze.
+	TiDBSysProcScanConcurrency = "tidb_sysproc_scan_concurrency"
 	// TiDBServerMemoryLimit indicates the memory limit of the tidb-server instance.
 	TiDBServerMemoryLimit = "tidb_server_memory_limit"
 	// TiDBServerMemoryLimitSessMinSize indicates the minimal memory used of a session, that becomes a candidate for session kill.
@@ -1084,6 +1088,8 @@ const (
 	MaxDDLReorgBatchSize                  int32  = 10240
 	MinDDLReorgBatchSize                  int32  = 32
 	MinExpensiveQueryTimeThreshold        uint64 = 10 // 10s
+	DefTiDBAutoBuildStatsConcurrency             = 1
+	DefTiDBSysProcScanConcurrency                = 1
 	DefTiDBRcWriteCheckTs                        = false
 	DefTiDBForeignKeyChecks                      = false
 	DefTiDBAnalyzePartitionConcurrency           = 1