ddl: consider paused job when check runnable

pkg/ddl/callback.go

@@ -60,9 +60,9 @@ type Callback interface {
 	// OnWatched is called after watching owner is completed.
 	OnWatched(ctx context.Context)
 	// OnGetJobBefore is called before getting job.
-	OnGetJobBefore(jobType string)
+	OnGetJobBefore()
 	// OnGetJobAfter is called after getting job.
-	OnGetJobAfter(jobType string, job *model.Job)
+	OnGetJobAfter(job *model.Job)
 }
 
 // BaseCallback implements Callback.OnChanged interface.
@@ -100,12 +100,12 @@ func (*BaseCallback) OnWatched(_ context.Context) {
 }
 
 // OnGetJobBefore implements Callback.OnGetJobBefore interface.
-func (*BaseCallback) OnGetJobBefore(_ string) {
+func (*BaseCallback) OnGetJobBefore() {
 	// Nothing to do.
 }
 
 // OnGetJobAfter implements Callback.OnGetJobAfter interface.
-func (*BaseCallback) OnGetJobAfter(_ string, _ *model.Job) {
+func (*BaseCallback) OnGetJobAfter(_ *model.Job) {
 	// Nothing to do.
 }
 

pkg/ddl/column.go

@@ -752,6 +752,7 @@ func (w *worker) doModifyColumnTypeWithData(
 			return ver, errors.Trace(err)
 		}
 		job.SchemaState = model.StateWriteOnly
+		failpoint.InjectCall("afterModifyColumnStateDeleteOnly", job.ID)
 	case model.StateWriteOnly:
 		// write only -> reorganization
 		updateChangingObjState(changingCol, changingIdxs, model.StateWriteReorganization)

pkg/ddl/ddl_running_jobs.go

@@ -233,11 +233,23 @@ func (j *runningJobs) addRunning(jobID int64, involves []model.InvolvingSchemaIn
 	}
 }
 
+func (j *runningJobs) finishOrPendJob(jobID int64, involves []model.InvolvingSchemaInfo, moveToPending bool) {
+	j.mu.Lock()
+	defer j.mu.Unlock()
+	j.removeRunningWithoutLock(jobID, involves)
+	if moveToPending {
+		j.addPendingWithoutLock(involves)
+	}
+}
+
 // removeRunning can be concurrently called with add and checkRunnable.
 func (j *runningJobs) removeRunning(jobID int64, involves []model.InvolvingSchemaInfo) {
 	j.mu.Lock()
 	defer j.mu.Unlock()
+	j.removeRunningWithoutLock(jobID, involves)
+}
 
+func (j *runningJobs) removeRunningWithoutLock(jobID int64, involves []model.InvolvingSchemaInfo) {
 	if intest.InTest {
 		if _, ok := j.ids[jobID]; !ok {
 			panic(fmt.Sprintf("job %d is not running", jobID))
@@ -296,6 +308,10 @@ func (j *runningJobs) addPending(involves []model.InvolvingSchemaInfo) {
 	j.mu.Lock()
 	defer j.mu.Unlock()
 
+	j.addPendingWithoutLock(involves)
+}
+
+func (j *runningJobs) addPendingWithoutLock(involves []model.InvolvingSchemaInfo) {
 	for _, info := range involves {
 		if info.Database != model.InvolvingNone {
 			if _, ok := j.pending.schemas[info.Database]; !ok {

pkg/ddl/ddl_worker_test.go

@@ -135,7 +135,7 @@ func TestParallelDDL(t *testing.T) {
 	}
 
 	once1 := sync.Once{}
-	tc.OnGetJobBeforeExported = func(string) {
+	tc.OnGetJobBeforeExported = func() {
 		once1.Do(func() {
 			for {
 				tk := testkit.NewTestKit(t, store)

pkg/ddl/job_table.go

@@ -185,51 +185,47 @@ func (s *jobScheduler) close() {
 }
 
 // getJob reads tidb_ddl_job and returns the first runnable DDL job.
-func (s *jobScheduler) getJob(se *sess.Session, tp jobType) (*model.Job, error) {
+func (s *jobScheduler) getJob(se *sess.Session) (*model.Job, bool, error) {
 	defer s.runningJobs.resetAllPending()
 
-	not := "not"
-	label := "get_job_general"
-	if tp == jobTypeReorg {
-		not = ""
-		label = "get_job_reorg"
-	}
-	const getJobSQL = `select job_meta, processing from mysql.tidb_ddl_job where job_id in
+	const getJobSQL = `select job_meta, processing, reorg from mysql.tidb_ddl_job where job_id in
 		(select min(job_id) from mysql.tidb_ddl_job group by schema_ids, table_ids, processing)
-		and %s reorg %s order by processing desc, job_id`
+		%s order by processing desc, job_id`
 	var excludedJobIDs string
 	if ids := s.runningJobs.allIDs(); len(ids) > 0 {
 		excludedJobIDs = fmt.Sprintf("and job_id not in (%s)", ids)
 	}
-	sql := fmt.Sprintf(getJobSQL, not, excludedJobIDs)
-	rows, err := se.Execute(context.Background(), sql, label)
+	sql := fmt.Sprintf(getJobSQL, excludedJobIDs)
+	rows, err := se.Execute(context.Background(), sql, "get_job")
 	if err != nil {
-		return nil, errors.Trace(err)
+		return nil, false, errors.Trace(err)
 	}
 	for _, row := range rows {
 		jobBinary := row.GetBytes(0)
 		isJobProcessing := row.GetInt64(1) == 1
+		isReorg := row.GetInt64(2) != 0
 
 		job := model.Job{}
 		err = job.Decode(jobBinary)
 		if err != nil {
-			return nil, errors.Trace(err)
+			return nil, isReorg, errors.Trace(err)
 		}
 
+		involving := job.GetInvolvingSchemaInfo()
 		isRunnable, err := s.processJobDuringUpgrade(se, &job)
 		if err != nil {
-			return nil, errors.Trace(err)
+			return nil, isReorg, errors.Trace(err)
 		}
 		if !isRunnable {
+			s.runningJobs.addPending(involving)
 			continue
 		}
 
 		// The job has already been picked up, just return to continue it.
 		if isJobProcessing {
-			return &job, nil
+			return &job, isReorg, nil
 		}
 
-		involving := job.GetInvolvingSchemaInfo()
 		if !s.runningJobs.checkRunnable(job.ID, involving) {
 			s.runningJobs.addPending(involving)
 			continue
@@ -241,11 +237,11 @@ func (s *jobScheduler) getJob(se *sess.Session, tp jobType) (*model.Job, error)
 				zap.Error(err),
 				zap.Stringer("job", &job))
 			s.runningJobs.addPending(involving)
-			return nil, errors.Trace(err)
+			return nil, isReorg, errors.Trace(err)
 		}
-		return &job, nil
+		return &job, isReorg, nil
 	}
-	return nil, nil
+	return nil, false, nil
 }
 
 func hasSysDB(job *model.Job) bool {
@@ -394,8 +390,7 @@ func (s *jobScheduler) startDispatch() error {
 			continue
 		}
 		failpoint.InjectCall("beforeAllLoadDDLJobAndRun")
-		s.loadDDLJobAndRun(se, s.generalDDLWorkerPool, jobTypeGeneral)
-		s.loadDDLJobAndRun(se, s.reorgWorkerPool, jobTypeReorg)
+		s.loadDDLJobAndRun(se)
 	}
 }
 
@@ -436,30 +431,32 @@ func (s *jobScheduler) checkAndUpdateClusterState(needUpdate bool) error {
 	return nil
 }
 
-func (s *jobScheduler) loadDDLJobAndRun(se *sess.Session, pool *workerPool, tp jobType) {
-	wk, err := pool.get()
-	if err != nil || wk == nil {
-		logutil.DDLLogger().Debug(fmt.Sprintf("[ddl] no %v worker available now", pool.tp()), zap.Error(err))
-		return
-	}
-
+func (s *jobScheduler) loadDDLJobAndRun(se *sess.Session) {
 	s.mu.RLock()
-	s.mu.hook.OnGetJobBefore(pool.tp().String())
+	s.mu.hook.OnGetJobBefore()
 	s.mu.RUnlock()
 
 	startTime := time.Now()
-	job, err := s.getJob(se, tp)
+	job, isReorg, err := s.getJob(se)
 	if job == nil || err != nil {
 		if err != nil {
-			wk.jobLogger(job).Warn("get job met error", zap.Duration("take time", time.Since(startTime)), zap.Error(err))
+			logutil.DDLLogger().Warn("get job met error", zap.Duration("take time", time.Since(startTime)), zap.Error(err))
 		}
-		pool.put(wk)
 		return
 	}
 	s.mu.RLock()
-	s.mu.hook.OnGetJobAfter(pool.tp().String(), job)
+	s.mu.hook.OnGetJobAfter(job)
 	s.mu.RUnlock()
 
+	pool := s.generalDDLWorkerPool
+	if isReorg {
+		pool = s.reorgWorkerPool
+	}
+	wk, err := pool.get()
+	if err != nil || wk == nil {
+		logutil.DDLLogger().Debug(fmt.Sprintf("[ddl] no %v worker available now", pool.tp()), zap.Error(err))
+		return
+	}
 	s.delivery2Worker(wk, pool, job)
 }
 
@@ -526,10 +523,18 @@ func (s *jobScheduler) delivery2Worker(wk *worker, pool *workerPool, job *model.
 	jobID, involvedSchemaInfos := job.ID, job.GetInvolvingSchemaInfo()
 	s.runningJobs.addRunning(jobID, involvedSchemaInfos)
 	metrics.DDLRunningJobCount.WithLabelValues(pool.tp().String()).Inc()
-	s.wg.RunWithLog(func() {
+	s.wg.Run(func() {
 		defer func() {
+			r := recover()
+			if r != nil {
+				logutil.DDLLogger().Error("panic in delivery2Worker", zap.Any("recover", r), zap.Stack("stack"))
+			}
 			failpoint.InjectCall("afterDelivery2Worker", job)
-			s.runningJobs.removeRunning(jobID, involvedSchemaInfos)
+			// Because there is a gap between `allIDs()` and `checkRunnable()`,
+			// we append unfinished job to pending atomically to prevent `getJob()`
+			// chosing another runnable job that involves the same schema object.
+			moveRunningJobsToPending := r != nil || (job != nil && !job.IsFinished())
+			s.runningJobs.finishOrPendJob(jobID, involvedSchemaInfos, moveRunningJobsToPending)
 			asyncNotify(s.ddlJobNotifyCh)
 			metrics.DDLRunningJobCount.WithLabelValues(pool.tp().String()).Dec()
 			pool.put(wk)

pkg/ddl/job_table_test.go

@@ -65,7 +65,7 @@ func TestDDLScheduling(t *testing.T) {
 	var wg util.WaitGroupWrapper
 	wg.Add(1)
 	var once sync.Once
-	hook.OnGetJobBeforeExported = func(jobType string) {
+	hook.OnGetJobBeforeExported = func() {
 		once.Do(func() {
 			for i, job := range ddlJobs {
 				wg.Run(func() {
@@ -91,7 +91,7 @@ func TestDDLScheduling(t *testing.T) {
 	}
 
 	record := make([]int64, 0, 16)
-	hook.OnGetJobAfterExported = func(jobType string, job *model.Job) {
+	hook.OnGetJobAfterExported = func(job *model.Job) {
 		// record the job schedule order
 		record = append(record, job.ID)
 	}

pkg/ddl/tests/adminpause/BUILD.bazel

@@ -29,7 +29,7 @@ go_test(
     ],
     embed = [":adminpause"],
     flaky = True,
-    shard_count = 14,
+    shard_count = 15,
     deps = [
         "//pkg/config",
         "//pkg/ddl",

pkg/ddl/tests/adminpause/pause_resume_test.go

@@ -20,7 +20,9 @@ import (
 	"strconv"
 	"sync"
 	"testing"
+	"time"
 
+	"github.com/pingcap/failpoint"
 	testddlutil "github.com/pingcap/tidb/pkg/ddl/testutil"
 	"github.com/pingcap/tidb/pkg/ddl/util/callback"
 	"github.com/pingcap/tidb/pkg/domain"
@@ -123,7 +125,7 @@ func pauseResumeAndCancel(t *testing.T, stmtKit *testkit.TestKit, adminCommandKi
 	var isCancelled = false
 	var cancelResult []sqlexec.RecordSet
 	var cancelErr error
-	var cancelFunc = func(jobType string) {
+	var cancelFunc = func() {
 		adminCommandMutex.Lock()
 		defer adminCommandMutex.Unlock()
 		if isPaused && isResumed && !isCancelled {
@@ -354,3 +356,60 @@ func TestPauseResumeCancelAndRerunPartitionTableStmt(t *testing.T) {
 
 	Logger.Info("TestPauseResumeCancelAndRerunPartitionTableStmt: all cases finished.")
 }
+
+func TestPauseJobDependency(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk2 := testkit.NewTestKit(t, store)
+	tk2.MustExec("use test")
+
+	tk.MustExec("create table t (a int, b int);")
+	tk.MustExec("insert into t values (1, 1);")
+
+	afterPause := make(chan struct{})
+	afterAddCol := make(chan struct{})
+	startAddCol := make(chan struct{})
+	var (
+		modifyJobID int64
+		errModCol   error
+		errAddCol   error
+	)
+	once := sync.Once{}
+	failpoint.EnableCall("github.com/pingcap/tidb/pkg/ddl/afterModifyColumnStateDeleteOnly", func(jobID int64) {
+		once.Do(func() {
+			modifyJobID = jobID
+			tk2.MustExec(fmt.Sprintf("admin pause ddl jobs %d", jobID))
+			afterPause <- struct{}{}
+		})
+	})
+	wg := sync.WaitGroup{}
+	wg.Add(2)
+	go func() {
+		defer wg.Done()
+		// Will stuck because the job is paused.
+		errModCol = tk.ExecToErr("alter table t modify column b tinyint;")
+	}()
+	go func() {
+		defer wg.Done()
+		<-afterPause
+		// This should be blocked because they handle the same table.
+		startAddCol <- struct{}{}
+		errAddCol = tk2.ExecToErr("alter table t add column c int;")
+		afterAddCol <- struct{}{}
+	}()
+	<-startAddCol
+	select {
+	case <-afterAddCol:
+		t.Logf("add column DDL on same table should be blocked")
+		t.FailNow()
+	case <-time.After(3 * time.Second):
+		tk3 := testkit.NewTestKit(t, store)
+		tk3.MustExec("use test")
+		tk3.MustExec(fmt.Sprintf("admin resume ddl jobs %d", modifyJobID))
+		<-afterAddCol
+	}
+	wg.Wait()
+	require.NoError(t, errModCol)
+	require.NoError(t, errAddCol)
+}

pkg/ddl/util/callback/callback.go

@@ -55,8 +55,8 @@ type TestDDLCallback struct {
 	onJobUpdated            func(*model.Job)
 	OnJobUpdatedExported    atomic.Pointer[func(*model.Job)]
 	onWatched               func(ctx context.Context)
-	OnGetJobBeforeExported  func(string)
-	OnGetJobAfterExported   func(string, *model.Job)
+	OnGetJobBeforeExported  func()
+	OnGetJobAfterExported   func(*model.Job)
 	OnJobSchemaStateChanged func(int64)
 
 	OnUpdateReorgInfoExported func(job *model.Job, pid int64)
@@ -146,21 +146,21 @@ func (tc *TestDDLCallback) OnWatched(ctx context.Context) {
 }
 
 // OnGetJobBefore implements Callback.OnGetJobBefore interface.
-func (tc *TestDDLCallback) OnGetJobBefore(jobType string) {
+func (tc *TestDDLCallback) OnGetJobBefore() {
 	if tc.OnGetJobBeforeExported != nil {
-		tc.OnGetJobBeforeExported(jobType)
+		tc.OnGetJobBeforeExported()
 		return
 	}
-	tc.BaseCallback.OnGetJobBefore(jobType)
+	tc.BaseCallback.OnGetJobBefore()
 }
 
 // OnGetJobAfter implements Callback.OnGetJobAfter interface.
-func (tc *TestDDLCallback) OnGetJobAfter(jobType string, job *model.Job) {
+func (tc *TestDDLCallback) OnGetJobAfter(job *model.Job) {
 	if tc.OnGetJobAfterExported != nil {
-		tc.OnGetJobAfterExported(jobType, job)
+		tc.OnGetJobAfterExported(job)
 		return
 	}
-	tc.BaseCallback.OnGetJobAfter(jobType, job)
+	tc.BaseCallback.OnGetJobAfter(job)
 }
 
 // Clone copies the callback and take its reference