exeuctor: fix coprocessor goroutine leak for IndexMerge

executor/index_merge_reader.go

@@ -361,6 +361,12 @@ func (e *IndexMergeReaderExecutor) startPartialIndexWorker(ctx context.Context,
 					SetFromInfoSchema(e.ctx.GetInfoSchema()).
 					SetClosestReplicaReadAdjuster(newClosestReadAdjuster(e.ctx, &builder.Request, e.partialNetDataSizes[workID]))
 
+				var notClosedSelectResult distsql.SelectResult
+				defer func() {
+					if notClosedSelectResult != nil {
+						terror.Call(notClosedSelectResult.Close)
+					}
+				}()
 				for parTblIdx, keyRange := range keyRanges {
 					// check if this executor is closed
 					select {
@@ -384,6 +390,11 @@ func (e *IndexMergeReaderExecutor) startPartialIndexWorker(ctx context.Context,
 						syncErr(ctx, e.finished, fetchCh, err)
 						return
 					}
+					notClosedSelectResult = result
+					failpoint.Inject("testIndexMergePartialIndexWorkerCoprLeak", func(v failpoint.Value) {
+						time.Sleep(time.Second * time.Duration(v.(int)))
+						panic("testIndexMergePartialIndexWorkerCoprLeak")
+					})
 					worker.batchSize = e.maxChunkSize
 					if worker.batchSize > worker.maxBatchSize {
 						worker.batchSize = worker.maxBatchSize
@@ -398,6 +409,7 @@ func (e *IndexMergeReaderExecutor) startPartialIndexWorker(ctx context.Context,
 					if fetchErr != nil { // this error is synced in fetchHandles(), don't sync it again
 						e.feedbacks[workID].Invalidate()
 					}
+					notClosedSelectResult = nil
 					if err := result.Close(); err != nil {
 						logutil.Logger(ctx).Error("close Select result failed:", zap.Error(err))
 					}
@@ -475,6 +487,13 @@ func (e *IndexMergeReaderExecutor) startPartialTableWorker(ctx context.Context,
 					partialTableReader.dagPB = e.dagPBs[workID]
 				}
 
+				var tableReaderClosed bool
+				defer func() {
+					// To make sure SelectResult.Close() is called even got panic in fetchHandles().
+					if !tableReaderClosed {
+						terror.Call(worker.tableReader.Close)
+					}
+				}()
 				for parTblIdx, tbl := range tbls {
 					// check if this executor is closed
 					select {
@@ -490,6 +509,11 @@ func (e *IndexMergeReaderExecutor) startPartialTableWorker(ctx context.Context,
 						syncErr(ctx, e.finished, fetchCh, err)
 						break
 					}
+					failpoint.Inject("testIndexMergePartialTableWorkerCoprLeak", func(v failpoint.Value) {
+						time.Sleep(time.Second * time.Duration(v.(int)))
+						panic("testIndexMergePartialTableWorkerCoprLeak")
+					})
+					tableReaderClosed = false
 					worker.batchSize = e.maxChunkSize
 					if worker.batchSize > worker.maxBatchSize {
 						worker.batchSize = worker.maxBatchSize
@@ -507,6 +531,7 @@ func (e *IndexMergeReaderExecutor) startPartialTableWorker(ctx context.Context,
 
 					// release related resources
 					cancel()
+					tableReaderClosed = true
 					if err = worker.tableReader.Close(); err != nil {
 						logutil.Logger(ctx).Error("close Select result failed:", zap.Error(err))
 					}

executor/index_merge_reader_test.go

@@ -881,3 +881,35 @@ func TestIndexMergePanic(t *testing.T) {
 		require.NoError(t, failpoint.Disable(fp))
 	}
 }
+
+func TestIndexMergeCoprGoroutinesLeak(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t1")
+	tk.MustExec("create table t1(c1 int, c2 bigint, c3 bigint, primary key(c1), key(c2), key(c3));")
+	insertStr := "insert into t1 values(0, 0, 0)"
+	for i := 1; i < 1000; i++ {
+		insertStr += fmt.Sprintf(", (%d, %d, %d)", i, i, i)
+	}
+	tk.MustExec(insertStr)
+	tk.MustExec("analyze table t1;")
+	tk.MustExec("set tidb_partition_prune_mode = 'dynamic'")
+
+	var err error
+	sql := "select /*+ use_index_merge(t1) */ c1 from t1 where c1 < 900 or c2 < 1000;"
+	res := tk.MustQuery("explain " + sql).Rows()
+	require.Contains(t, res[1][0], "IndexMerge")
+
+	// If got goroutines leak in coprocessor, ci will fail.
+	require.NoError(t, failpoint.Enable("github.com/pingcap/tidb/executor/testIndexMergePartialTableWorkerCoprLeak", "return(3)"))
+	err = tk.QueryToErr(sql)
+	require.Contains(t, err.Error(), "testIndexMergePartialTableWorkerCoprLeak")
+	require.NoError(t, failpoint.Disable("github.com/pingcap/tidb/executor/testIndexMergePartialTableWorkerCoprLeak"))
+
+	require.NoError(t, failpoint.Enable("github.com/pingcap/tidb/executor/testIndexMergePartialIndexWorkerCoprLeak", "return(3)"))
+	err = tk.QueryToErr(sql)
+	require.Contains(t, err.Error(), "testIndexMergePartialIndexWorkerCoprLeak")
+	require.NoError(t, failpoint.Disable("github.com/pingcap/tidb/executor/testIndexMergePartialIndexWorkerCoprLeak"))
+}