ddl: add ddl job error count limit, exceed the limit should cancel the ddl job

ddl/ddl_worker.go

@@ -23,11 +23,14 @@ import (
 	"github.com/pingcap/errors"
 	"github.com/pingcap/parser/model"
 	"github.com/pingcap/parser/terror"
+	"github.com/pingcap/tidb/ddl/util"
 	"github.com/pingcap/tidb/kv"
 	"github.com/pingcap/tidb/meta"
 	"github.com/pingcap/tidb/metrics"
 	"github.com/pingcap/tidb/sessionctx"
 	"github.com/pingcap/tidb/sessionctx/binloginfo"
+	"github.com/pingcap/tidb/sessionctx/variable"
+	"github.com/pingcap/tidb/util/admin"
 	log "github.com/sirupsen/logrus"
 )
 
@@ -537,10 +540,30 @@ func (w *worker) runDDLJob(d *ddlCtx, t *meta.Meta, job *model.Job) (ver int64,
 
 		job.Error = toTError(err)
 		job.ErrorCount++
+		// Load global ddl variables.
+		if err1 := loadDDLVars(w); err1 != nil {
+			log.Errorf("[ddl-%s] load ddl global variable error: %v", w, err1)
+		}
+		// Check error limit to avoid falling into an infinite loop.
+		if job.ErrorCount > variable.GetDDLErrorCountLimit() && job.State == model.JobStateRunning && admin.IsJobRollbackable(job) {
+			log.Warnf("[ddl-%s] the job id %v error count exceed the limit, cancelling it now", w, job.ID)
+			job.State = model.JobStateCancelling
+		}
 	}
 	return
 }
 
+func loadDDLVars(w *worker) error {
+	// Get sessionctx from context resource pool.
+	var ctx sessionctx.Context
+	ctx, err := w.sessPool.get()
+	if err != nil {
+		return errors.Trace(err)
+	}
+	defer w.sessPool.put(ctx)
+	return util.LoadDDLVars(ctx)
+}
+
 func toTError(err error) *terror.Error {
 	originErr := errors.Cause(err)
 	tErr, ok := originErr.(*terror.Error)

ddl/serial_test.go

@@ -458,3 +458,14 @@ func (s *testSerialSuite) TestRestoreTableByTableNameFail(c *C) {
 	tk.MustExec("insert into t_recover values (4),(5),(6)")
 	tk.MustQuery("select * from t_recover;").Check(testkit.Rows("1", "2", "3", "4", "5", "6"))
 }
+
+func (s *testSerialSuite) TestCancelJobByErrorCountLimit(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	gofail.Enable("github.com/pingcap/tidb/ddl/mockExceedErrorLimit", `return(true)`)
+	defer gofail.Disable("github.com/pingcap/tidb/ddl/mockExceedErrorLimit")
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t")
+	_, err := tk.Exec("create table t (a int)")
+	c.Assert(err, NotNil)
+	c.Assert(err.Error(), Equals, "[ddl:12]cancelled DDL job")
+}

ddl/table.go

@@ -33,6 +33,11 @@ import (
 )
 
 func onCreateTable(d *ddlCtx, t *meta.Meta, job *model.Job) (ver int64, _ error) {
+	// gofail: var mockExceedErrorLimit bool
+	// if mockExceedErrorLimit {
+	//    return ver, errors.New("mock do job error")
+	// }
+
 	schemaID := job.SchemaID
 	tbInfo := &model.TableInfo{}
 	if err := job.DecodeArgs(tbInfo); err != nil {

ddl/util/util.go

@@ -135,14 +135,30 @@ func UpdateDeleteRange(ctx sessionctx.Context, dr DelRangeTask, newStartKey, old
 	return errors.Trace(err)
 }
 
-const loadDDLReorgVarsSQL = "select HIGH_PRIORITY variable_name, variable_value from mysql.global_variables where variable_name in ('" +
-	variable.TiDBDDLReorgWorkerCount + "', '" +
-	variable.TiDBDDLReorgBatchSize + "')"
-
 // LoadDDLReorgVars loads ddl reorg variable from mysql.global_variables.
 func LoadDDLReorgVars(ctx sessionctx.Context) error {
+	return LoadGlobalVars(ctx, []string{variable.TiDBDDLReorgWorkerCount, variable.TiDBDDLReorgBatchSize})
+}
+
+// LoadDDLVars loads ddl variable from mysql.global_variables.
+func LoadDDLVars(ctx sessionctx.Context) error {
+	return LoadGlobalVars(ctx, []string{variable.TiDBDDLErrorCountLimit})
+}
+
+const loadGlobalVarsSQL = "select HIGH_PRIORITY variable_name, variable_value from mysql.global_variables where variable_name in (%s)"
+
+// LoadGlobalVars loads global variable from mysql.global_variables.
+func LoadGlobalVars(ctx sessionctx.Context, varNames []string) error {
 	if sctx, ok := ctx.(sqlexec.RestrictedSQLExecutor); ok {
-		rows, _, err := sctx.ExecRestrictedSQL(ctx, loadDDLReorgVarsSQL)
+		nameList := ""
+		for i, name := range varNames {
+			if i > 0 {
+				nameList += ", "
+			}
+			nameList += fmt.Sprintf("'%s'", name)
+		}
+		sql := fmt.Sprintf(loadGlobalVarsSQL, nameList)
+		rows, _, err := sctx.ExecRestrictedSQL(ctx, sql)
 		if err != nil {
 			return errors.Trace(err)
 		}

executor/ddl_test.go

@@ -595,6 +595,33 @@ func (s *testSuite3) TestSetDDLReorgBatchSize(c *C) {
 	res.Check(testkit.Rows("1000"))
 }
 
+func (s *testSuite3) TestSetDDLErrorCountLimit(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	err := ddlutil.LoadDDLVars(tk.Se)
+	c.Assert(err, IsNil)
+	c.Assert(variable.GetDDLErrorCountLimit(), Equals, int64(variable.DefTiDBDDLErrorCountLimit))
+
+	tk.MustExec("set @@global.tidb_ddl_error_count_limit = -1")
+	tk.MustQuery("show warnings;").Check(testkit.Rows("Warning 1292 Truncated incorrect tidb_ddl_error_count_limit value: '-1'"))
+	err = ddlutil.LoadDDLVars(tk.Se)
+	c.Assert(err, IsNil)
+	c.Assert(variable.GetDDLErrorCountLimit(), Equals, int64(0))
+	tk.MustExec(fmt.Sprintf("set @@global.tidb_ddl_error_count_limit = %v", uint64(math.MaxInt64)+1))
+	tk.MustQuery("show warnings;").Check(testkit.Rows(fmt.Sprintf("Warning 1292 Truncated incorrect tidb_ddl_error_count_limit value: '%d'", uint64(math.MaxInt64)+1)))
+	err = ddlutil.LoadDDLVars(tk.Se)
+	c.Assert(err, IsNil)
+	c.Assert(variable.GetDDLErrorCountLimit(), Equals, int64(math.MaxInt64))
+	_, err = tk.Exec("set @@global.tidb_ddl_error_count_limit = invalid_val")
+	c.Assert(terror.ErrorEqual(err, variable.ErrWrongTypeForVar), IsTrue, Commentf("err %v", err))
+	tk.MustExec("set @@global.tidb_ddl_error_count_limit = 100")
+	err = ddlutil.LoadDDLVars(tk.Se)
+	c.Assert(err, IsNil)
+	c.Assert(variable.GetDDLErrorCountLimit(), Equals, int64(100))
+	res := tk.MustQuery("select @@global.tidb_ddl_error_count_limit")
+	res.Check(testkit.Rows("100"))
+}
+
 // Test issue #9205, fix the precision problem for time type default values
 // See https://github.com/pingcap/tidb/issues/9205 for details
 func (s *testSuite3) TestIssue9205(c *C) {

session/session.go

@@ -1480,6 +1480,7 @@ var builtinGlobalVariable = []string{
 	variable.TiDBConstraintCheckInPlace,
 	variable.TiDBDDLReorgWorkerCount,
 	variable.TiDBDDLReorgBatchSize,
+	variable.TiDBDDLErrorCountLimit,
 	variable.TiDBOptInSubqToJoinAndAgg,
 	variable.TiDBDistSQLScanConcurrency,
 	variable.TiDBInitChunkSize,

sessionctx/variable/session.go

@@ -701,6 +701,8 @@ func SetLocalSystemVar(name string, val string) {
 		SetDDLReorgWorkerCounter(int32(tidbOptPositiveInt32(val, DefTiDBDDLReorgWorkerCount)))
 	case TiDBDDLReorgBatchSize:
 		SetDDLReorgBatchSize(int32(tidbOptPositiveInt32(val, DefTiDBDDLReorgBatchSize)))
+	case TiDBDDLErrorCountLimit:
+		SetDDLErrorCountLimit(tidbOptInt64(val, DefTiDBDDLErrorCountLimit))
 	}
 }
 

sessionctx/variable/sysvar.go

@@ -678,6 +678,7 @@ var defaultSysVars = []*SysVar{
 	{ScopeSession, TiDBConfig, ""},
 	{ScopeGlobal, TiDBDDLReorgWorkerCount, strconv.Itoa(DefTiDBDDLReorgWorkerCount)},
 	{ScopeGlobal, TiDBDDLReorgBatchSize, strconv.Itoa(DefTiDBDDLReorgBatchSize)},
+	{ScopeGlobal, TiDBDDLErrorCountLimit, strconv.Itoa(DefTiDBDDLErrorCountLimit)},
 	{ScopeSession, TiDBDDLReorgPriority, "PRIORITY_LOW"},
 	{ScopeSession, TiDBForcePriority, mysql.Priority2Str[DefTiDBForcePriority]},
 	{ScopeSession, TiDBEnableRadixJoin, boolToIntStr(DefTiDBUseRadixJoin)},

sessionctx/variable/tidb_vars.go

@@ -210,6 +210,9 @@ const (
 	// tidb_ddl_reorg_batch_size defines the transaction batch size of ddl reorg workers.
 	TiDBDDLReorgBatchSize = "tidb_ddl_reorg_batch_size"
 
+	// tidb_ddl_error_count_limit defines the count of ddl error limit.
+	TiDBDDLErrorCountLimit = "tidb_ddl_error_count_limit"
+
 	// tidb_ddl_reorg_priority defines the operations priority of adding indices.
 	// It can be: PRIORITY_LOW, PRIORITY_NORMAL, PRIORITY_HIGH
 	TiDBDDLReorgPriority = "tidb_ddl_reorg_priority"
@@ -273,6 +276,7 @@ const (
 	DefTiDBOptimizerSelectivityLevel = 0
 	DefTiDBDDLReorgWorkerCount       = 16
 	DefTiDBDDLReorgBatchSize         = 1024
+	DefTiDBDDLErrorCountLimit        = 512
 	DefTiDBHashAggPartialConcurrency = 4
 	DefTiDBHashAggFinalConcurrency   = 4
 	DefTiDBForcePriority             = mysql.NoPriority
@@ -286,6 +290,7 @@ var (
 	ddlReorgWorkerCounter  int32 = DefTiDBDDLReorgWorkerCount
 	maxDDLReorgWorkerCount int32 = 128
 	ddlReorgBatchSize      int32 = DefTiDBDDLReorgBatchSize
+	ddlErrorCountlimit     int64 = DefTiDBDDLErrorCountLimit
 	// Export for testing.
 	MaxDDLReorgBatchSize int32  = 10240
 	MinDDLReorgBatchSize int32  = 32

sessionctx/variable/varsutil.go

@@ -63,6 +63,16 @@ func GetDDLReorgBatchSize() int32 {
 	return atomic.LoadInt32(&ddlReorgBatchSize)
 }
 
+// SetDDLErrorCountLimit sets ddlErrorCountlimit size.
+func SetDDLErrorCountLimit(cnt int64) {
+	atomic.StoreInt64(&ddlErrorCountlimit, cnt)
+}
+
+// GetDDLErrorCountLimit gets ddlErrorCountlimit size.
+func GetDDLErrorCountLimit() int64 {
+	return atomic.LoadInt64(&ddlErrorCountlimit)
+}
+
 // GetSessionSystemVar gets a system variable.
 // If it is a session only variable, use the default value defined in code.
 // Returns error if there is no such variable.
@@ -360,6 +370,8 @@ func ValidateSetSystemVar(vars *SessionVars, name string, value string) (string,
 		return value, ErrWrongValueForVar.GenWithStackByArgs(name, value)
 	case TiDBDDLReorgBatchSize:
 		return checkUInt64SystemVar(name, value, uint64(MinDDLReorgBatchSize), uint64(MaxDDLReorgBatchSize), vars)
+	case TiDBDDLErrorCountLimit:
+		return checkUInt64SystemVar(name, value, uint64(0), math.MaxInt64, vars)
 	case TiDBIndexLookupConcurrency, TiDBIndexLookupJoinConcurrency, TiDBIndexJoinBatchSize,
 		TiDBIndexLookupSize,
 		TiDBHashJoinConcurrency,

util/admin/admin.go

@@ -83,26 +83,27 @@ func GetDDLInfo(txn kv.Transaction) (*DDLInfo, error) {
 	return info, nil
 }
 
-func isJobRollbackable(job *model.Job, id int64) error {
+// IsJobRollbackable checks whether the job can be rollback.
+func IsJobRollbackable(job *model.Job) bool {
 	switch job.Type {
 	case model.ActionDropIndex:
 		// We can't cancel if index current state is in StateDeleteOnly or StateDeleteReorganization, otherwise will cause inconsistent between record and index.
 		if job.SchemaState == model.StateDeleteOnly ||
 			job.SchemaState == model.StateDeleteReorganization {
-			return ErrCannotCancelDDLJob.GenWithStackByArgs(id)
+			return false
 		}
 	case model.ActionDropColumn:
 		if job.SchemaState != model.StateNone {
-			return ErrCannotCancelDDLJob.GenWithStackByArgs(id)
+			return false
 		}
 	case model.ActionDropSchema, model.ActionDropTable:
 		// To simplify the rollback logic, cannot be canceled in the following states.
 		if job.SchemaState == model.StateWriteOnly ||
 			job.SchemaState == model.StateDeleteOnly {
-			return ErrCannotCancelDDLJob.GenWithStackByArgs(id)
+			return false
 		}
 	}
-	return nil
+	return true
 }
 
 // CancelJobs cancels the DDL jobs.
@@ -135,8 +136,8 @@ func CancelJobs(txn kv.Transaction, ids []int64) ([]error, error) {
 			if job.IsCancelled() || job.IsRollingback() || job.IsRollbackDone() {
 				continue
 			}
-			errs[i] = isJobRollbackable(job, id)
-			if errs[i] != nil {
+			if !IsJobRollbackable(job) {
+				errs[i] = ErrCannotCancelDDLJob.GenWithStackByArgs(job.ID)
 				continue
 			}