Fix 2090 child workflow goroutine leak

internal/internal_workflow_testsuite.go

@@ -236,6 +236,7 @@ type (
 		testResult          converter.EncodedValue
 		testError           error
 		doneChannel         chan struct{}
+		doneChannelOnce     sync.Once
 		workerOptions       WorkerOptions
 		dataConverter       converter.DataConverter
 		failureConverter    converter.FailureConverter
@@ -830,7 +831,11 @@ func (env *testWorkflowEnvironmentImpl) startWorkflowTask() {
 func (env *testWorkflowEnvironmentImpl) isChildWorkflow() bool {
 	return env.parentEnv != nil
 }
-
+func (env *testWorkflowEnvironmentImpl) closeDoneChannel() {
+	env.doneChannelOnce.Do(func() {
+		close(env.doneChannel)
+	})
+}
 func (env *testWorkflowEnvironmentImpl) startMainLoop() {
 	if env.isChildWorkflow() {
 		// child workflow rely on parent workflow's main loop to process events
@@ -839,7 +844,7 @@ func (env *testWorkflowEnvironmentImpl) startMainLoop() {
 	}
 
 	// notify all child workflows to exit their main loop
-	defer close(env.doneChannel)
+	defer env.closeDoneChannel()
 
 	for !env.shouldStopEventLoop() {
 		// use non-blocking-select to check if there is anything pending in the main thread.
@@ -1100,6 +1105,7 @@ func (env *testWorkflowEnvironmentImpl) Complete(result *commonpb.Payloads, err
 
 	// properly handle child workflows based on their ParentClosePolicy
 	env.handleParentClosePolicy()
+	env.closeDoneChannel()
 }
 
 func (env *testWorkflowEnvironmentImpl) handleParentClosePolicy() {

test/child_workflow_leak_test.go

@@ -0,0 +1,42 @@
+package test
+
+import (
+	"testing"
+
+	"go.temporal.io/sdk/testsuite"
+	"go.temporal.io/sdk/workflow"
+	"go.uber.org/goleak"
+)
+
+func ChildWorkflow(ctx workflow.Context) (string, error) {
+	return "ok", nil
+}
+
+func ParentWorkflow(ctx workflow.Context) (string, error) {
+	// Execute child by *registered name* (the path that triggered #2090).
+	var out string
+	if err := workflow.ExecuteChildWorkflow(ctx, "ChildWorkflow").Get(ctx, &out); err != nil {
+		return "", err
+	}
+	return out, nil
+}
+
+func TestChildWorkflowByName_NoGoroutineLeak(t *testing.T) {
+	defer goleak.VerifyNone(t)
+
+	var suite testsuite.WorkflowTestSuite
+	env := suite.NewTestWorkflowEnvironment()
+
+	// Register child under the name we call above.
+	env.RegisterWorkflowWithOptions(ChildWorkflow, workflow.RegisterOptions{Name: "ChildWorkflow"})
+	env.RegisterWorkflow(ParentWorkflow)
+
+	env.ExecuteWorkflow(ParentWorkflow)
+
+	if !env.IsWorkflowCompleted() {
+		t.Fatal("workflow did not complete")
+	}
+	if err := env.GetWorkflowError(); err != nil {
+		t.Fatalf("workflow failed: %v", err)
+	}
+}