pkg/executor: fix the hang issue in indexHashJoin

pkg/executor/builder.go

@@ -4683,6 +4683,9 @@ func buildKvRangesForIndexJoin(ctx sessionctx.Context, tableID, indexID int64, l
 		}
 	}
 	if len(kvRanges) != 0 && memTracker != nil {
+		failpoint.Inject("testIssue49033", func() {
+			panic("testIssue49033")
+		})
 		memTracker.Consume(int64(2 * cap(kvRanges[0].StartKey) * len(kvRanges)))
 	}
 	if len(tmpDatumRanges) != 0 && memTracker != nil {

pkg/executor/index_lookup_hash_join.go

@@ -75,6 +75,9 @@ type IndexNestedLoopHashJoin struct {
 
 	stats    *indexLookUpJoinRuntimeStats
 	prepared bool
+	// panicErr records the error generated by panic recover. This is introduced to
+	// return the actual error message instead of `context cancelled` to the client.
+	panicErr error
 }
 
 type indexHashJoinOuterWorker struct {
@@ -143,7 +146,7 @@ func (e *IndexNestedLoopHashJoin) Open(ctx context.Context) error {
 	return nil
 }
 
-func (e *IndexNestedLoopHashJoin) startWorkers(ctx context.Context) {
+func (e *IndexNestedLoopHashJoin) startWorkers(ctx context.Context) (ctxWithCancel context.Context) {
 	concurrency := e.Ctx().GetSessionVars().IndexLookupJoinConcurrency()
 	if e.stats != nil {
 		e.stats.concurrency = concurrency
@@ -182,6 +185,7 @@ func (e *IndexNestedLoopHashJoin) startWorkers(ctx context.Context) {
 		go util.WithRecovery(func() { e.newInnerWorker(innerCh, workerID).run(workerCtx, cancelFunc) }, e.finishJoinWorkers)
 	}
 	go e.wait4JoinWorkers()
+	return workerCtx
 }
 
 func (e *IndexNestedLoopHashJoin) finishJoinWorkers(r interface{}) {
@@ -197,6 +201,7 @@ func (e *IndexNestedLoopHashJoin) finishJoinWorkers(r interface{}) {
 			task := &indexHashJoinTask{err: err}
 			e.taskCh <- task
 		}
+		e.panicErr = err
 		if e.cancelFunc != nil {
 			e.cancelFunc()
 		}
@@ -217,64 +222,44 @@ func (e *IndexNestedLoopHashJoin) wait4JoinWorkers() {
 // Next implements the IndexNestedLoopHashJoin Executor interface.
 func (e *IndexNestedLoopHashJoin) Next(ctx context.Context, req *chunk.Chunk) error {
 	if !e.prepared {
-		e.startWorkers(ctx)
+		ctx = e.startWorkers(ctx)
 		e.prepared = true
 	}
 	req.Reset()
 	if e.keepOuterOrder {
 		return e.runInOrder(ctx, req)
 	}
-	// unordered run
-	var (
-		result *indexHashJoinResult
-		ok     bool
-	)
-	select {
-	case result, ok = <-e.resultCh:
-		if !ok {
-			return nil
-		}
-		if result.err != nil {
-			return result.err
-		}
-	case <-ctx.Done():
-		return ctx.Err()
-	}
-	req.SwapColumns(result.chk)
-	result.src <- result.chk
-	return nil
+	return e.runUnordered(ctx, req)
 }
 
 func (e *IndexNestedLoopHashJoin) runInOrder(ctx context.Context, req *chunk.Chunk) error {
-	var (
-		result *indexHashJoinResult
-		ok     bool
-	)
 	for {
 		if e.isDryUpTasks(ctx) {
 			return nil
 		}
 		if e.curTask.err != nil {
 			return e.curTask.err
 		}
-		select {
-		case result, ok = <-e.curTask.resultCh:
-			if !ok {
-				e.curTask = nil
-				continue
-			}
-			if result.err != nil {
-				return result.err
-			}
-		case <-ctx.Done():
-			return ctx.Err()
+		result, err := e.getResultFromChannel(ctx, e.curTask.resultCh)
+		if err != nil {
+			return err
 		}
-		req.SwapColumns(result.chk)
-		result.src <- result.chk
-		return nil
+		if result == nil {
+			e.curTask = nil
+			continue
+		}
+		return e.handleResult(ctx, req, result)
 	}
 }
 
+func (e *IndexNestedLoopHashJoin) runUnordered(ctx context.Context, req *chunk.Chunk) error {
+	result, err := e.getResultFromChannel(ctx, e.resultCh)
+	if err != nil {
+		return err
+	}
+	return e.handleResult(ctx, req, result)
+}
+
 // isDryUpTasks indicates whether all the tasks have been processed.
 func (e *IndexNestedLoopHashJoin) isDryUpTasks(ctx context.Context) bool {
 	if e.curTask != nil {
@@ -292,6 +277,38 @@ func (e *IndexNestedLoopHashJoin) isDryUpTasks(ctx context.Context) bool {
 	return false
 }
 
+func (e *IndexNestedLoopHashJoin) getResultFromChannel(ctx context.Context, resultCh <-chan *indexHashJoinResult) (*indexHashJoinResult, error) {
+	var (
+		result *indexHashJoinResult
+		ok     bool
+	)
+	select {
+	case result, ok = <-resultCh:
+		if !ok {
+			return nil, nil
+		}
+		if result.err != nil {
+			return nil, result.err
+		}
+	case <-ctx.Done():
+		err := e.panicErr
+		if err == nil {
+			err = ctx.Err()
+		}
+		return nil, err
+	}
+	return result, nil
+}
+
+func (e *IndexNestedLoopHashJoin) handleResult(ctx context.Context, req *chunk.Chunk, result *indexHashJoinResult) error {
+	if result == nil {
+		return nil
+	}
+	req.SwapColumns(result.chk)
+	result.src <- result.chk
+	return nil
+}
+
 // Close implements the IndexNestedLoopHashJoin Executor interface.
 func (e *IndexNestedLoopHashJoin) Close() error {
 	if e.stats != nil {

pkg/executor/test/jointest/join_test.go

@@ -861,3 +861,36 @@ func TestIssue37932(t *testing.T) {
 	}
 	require.NoError(t, err)
 }
+
+func TestIssue49033(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test;")
+	tk.MustExec("drop table if exists t, s;")
+	tk.MustExec("create table t(a int, index(a));")
+	tk.MustExec("create table s(a int, index(a));")
+	tk.MustExec("insert into t values(1), (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12), (13), (14), (15), (16), (17), (18), (19), (20), (21), (22), (23), (24), (25), (26), (27), (28), (29), (30), (31), (32), (33), (34), (35), (36), (37), (38), (39), (40), (41), (42), (43), (44), (45), (46), (47), (48), (49), (50), (51), (52), (53), (54), (55), (56), (57), (58), (59), (60), (61), (62), (63), (64), (65), (66), (67), (68), (69), (70), (71), (72), (73), (74), (75), (76), (77), (78), (79), (80), (81), (82), (83), (84), (85), (86), (87), (88), (89), (90), (91), (92), (93), (94), (95), (96), (97), (98), (99), (100), (101), (102), (103), (104), (105), (106), (107), (108), (109), (110), (111), (112), (113), (114), (115), (116), (117), (118), (119), (120), (121), (122), (123), (124), (125), (126), (127), (128);")
+	tk.MustExec("insert into s values(1), (128);")
+	tk.MustExec("set @@tidb_max_chunk_size=32;")
+	tk.MustExec("set @@tidb_index_lookup_join_concurrency=1;")
+	tk.MustExec("set @@tidb_index_join_batch_size=32;")
+	tk.MustQuery("select /*+ INL_HASH_JOIN(s) */ * from t join s on t.a=s.a;")
+	tk.MustQuery("select /*+ INL_HASH_JOIN(s) */ * from t join s on t.a=s.a order by t.a;")
+
+	require.NoError(t, failpoint.Enable("github.com/pingcap/tidb/pkg/executor/testIssue49033", "return"))
+	defer func() {
+		require.NoError(t, failpoint.Disable("github.com/pingcap/tidb/pkg/executor/testIssue49033"))
+	}()
+
+	rs, err := tk.Exec("select /*+ INL_HASH_JOIN(s) */ * from t join s on t.a=s.a order by t.a;")
+	require.NoError(t, err)
+	_, err = session.GetRows4Test(context.Background(), nil, rs)
+	require.EqualError(t, err, "testIssue49033")
+	require.NoError(t, rs.Close())
+
+	rs, err = tk.Exec("select /*+ INL_HASH_JOIN(s) */ * from t join s on t.a=s.a")
+	require.NoError(t, err)
+	_, err = session.GetRows4Test(context.Background(), nil, rs)
+	require.EqualError(t, err, "testIssue49033")
+	require.NoError(t, rs.Close())
+}