Complete Parent workflow, once ChildWorkflow is scheduled/started

workflow · April 18, 2023, 10:33pm

I want my parent workflow to call a long running child workflow asynchronously.
I want to keep it untype (for future flexibility). so here is what I am doing as per docs

        val childUntyped = Workflow.newUntypedChildWorkflowStub(
            workflowType,
            ChildWorkflowOptions.newBuilder()
                .setWorkflowId(workflowId)
                .setTaskQueue(taskQueue)
                .setParentClosePolicy(ParentClosePolicy.PARENT_CLOSE_POLICY_ABANDON)
                .build()
        )
     
        val childExecution = childUntyped.executeAsync(
            Unit.javaClass,
            definition
        )
        // Important:This is to ensure that a Child Workflow Execution starts before the parent closes.
        // If the parent initiates a Child Workflow Execution and then completes immediately after,
        // the Child Workflow will never execute. Refer: https://docs.temporal.io/application-development/features?lang=java#parent-close-policy
        childExecution.get()

        log.info("Successfully Scheduled Child workflow")

both workflows are kicked off.

child workflow has a timer and is still running.
I expected the parent workflow to complete after the child workflow has started. but I see it is still waiting for the promise - childExecution.get()

I am not sure why the promise is not returned after child has started?

maxim · April 18, 2023, 10:41pm

ChildWorkflowStub.executeAsync returns a Promise that becomes ready when a child workflow completes. Use ChildWorkflowStub.getExecution() to get a Promise that becomes ready when the child workflow starts.

Zach_Attas · October 26, 2023, 1:16am

@maxim if you are using ChildWorkflowStub.getExecution(), how would you pass a payload to the child workflow? With executeAsync, one of the arguments is args, which is where the WorkflowExecutionStarted data comes from I think, but I’m not seeing a way to do that with getExecution

maxim · October 27, 2023, 5:48pm

See this sample: Best way to create an async child workflow - #2 by maxim

Zach_Attas · October 27, 2023, 6:17pm

Is there an example for newUntypedChildWorkflowStub? That example has the child workflow being typed

maxim · October 27, 2023, 9:31pm

Use

child = Workflow.newUntypedChildWorkflowStub(workflowType, childOptions);
Promise<...> result =child.executeAsync(..., args);
child.getExecution().get();

Zach_Attas · October 30, 2023, 2:33pm

It does not look like that is possible? I can’t seem to call getExecution on the promise

I’m on temporal-sdk:1.21.1

antonio.perez · October 30, 2023, 6:16pm

Hi @Zach_Attas

I think it is on the UntypedChildWorkflowStub : childUntyped.getExecution()

Let me know if it works.
Antonio

Zach_Attas · October 30, 2023, 6:20pm

Thanks @antonio.perez will try that! And now, however, SUPER struggling to unit test this behavior as well, since, the examples for unit testing parent-> child stuff do it with typed workflows…how would one unit test the untyped variety?

Zach_Attas · October 31, 2023, 3:45pm

Also, I tested UntypedChildWorkflowStub : childUntyped.getExecution()

It did not work, it said that the execution was Initialized, but never created the child workflow

antonio.perez · October 31, 2023, 5:48pm

ok let me test this and come back.

Is the issue with the test mocking the child workflow?

Zach_Attas · October 31, 2023, 6:49pm

Its 2 issues,

How do you properly kick off an UNTYPED child workflow, and get the parent workflow to report when the child workflow STARTED, but not stay open for the whole child execution, aka, have the parent be done when the child is certain that it is entered into temporal and/or started but not stay open. If it stays open, it makes our workflow slower, and its harder to measure the speed of each individual workflow. We don’t need the parent to stay open while the child executes
How do you unit test said behavior? When I wrote tests without doing this, they just hang. But I’m not sure also how to implement that example, with an UNTYPED child workflow

antonio.perez · November 1, 2023, 9:48am

@Zach_Attas

I have written an example with the implementation

github.com

antmendoza/temporal_samples-java/blob/b19255791701db48af7eed3c18d06d7557700163/core/src/main/java/io/temporal/samples/asyncuntypedchild/ParentWorkflowImpl.java#L52


      
                          .setWorkflowId("Child_of_" + WORKFLOW_ID)
                          .build());
          
              /*
               * Invoke the child workflows composeGreeting workflow method async.
               * This call is non-blocking and returns immediately returning a {@link io.temporal.workflow.Promise},
               * you can invoke `get()` on the returned promise to wait for the child workflow result.
               */
              child.executeAsync(String.class, "Hello", name);
          
              // Wait for the child workflow to start before returning the result
              Promise<WorkflowExecution> childExecution = child.getExecution();
              WorkflowExecution childWorkflowExecution = childExecution.get();
          
              // return the child workflowId
              return childWorkflowExecution.getWorkflowId();
            }
          }

and the test

github.com

antmendoza/temporal_samples-java/blob/b19255791701db48af7eed3c18d06d7557700163/core/src/test/java/io/temporal/samples/asyncuntypedchild/AsyncUntypedChildTest.java#L73


      
            WorkflowClient workflowClient = testWorkflowRule.getWorkflowClient();
            ParentWorkflow workflow =
                workflowClient.newWorkflowStub(
                    ParentWorkflow.class,
                    WorkflowOptions.newBuilder().setTaskQueue(testWorkflowRule.getTaskQueue()).build());
          
            // Execute the parent workflow and wait for it to complete.
            String childWorkflowId = workflow.getGreeting("World");
            assertNotNull(childWorkflowId);
          
            assertEquals(
                WORKFLOW_EXECUTION_STATUS_RUNNING,
                getChildWorkflowExecutionStatus(workflowClient, childWorkflowId));
          
            // Wait for the child to complete
            String childResult =
                workflowClient.newUntypedWorkflowStub(childWorkflowId).getResult(String.class);
            assertEquals("Hello World from mocked child!", childResult);
          
            testWorkflowRule.getTestEnvironment().shutdown();
          }

Let me know if it helps,

Antonio

Zach_Attas · November 1, 2023, 2:20pm

My issue with the unit test example is here https://github.com/antmendoza/temporal_samples-java/blob/b19255791701db48af7eed3c18d06d7557700163/core/src/test/java/io/temporal/samples/asyncuntypedchild/AsyncUntypedChildTest.java#L49C5-L58C16

I don’t have the child workflow defined in this repo, its another repo, which is why im using the untyped strategy

antonio.perez · November 1, 2023, 3:51pm

@Zach_Attas

I guess then the child is running in a different taskqueue?

If you don’t need to test if the child is running, just remove registerWorkflowImplementationFactory and the asserts related to the child workflow from test code.

If you need to test the child is running after the parent has completed,

I think you still need an interface:

    //worker listening in the child taskqueue
    Worker workerChildTaskqueue =
        testWorkflowRule.getTestEnvironment().newWorker("child-taskqueue");

    // Factory is called to create a new workflow object on each workflow task.
    workerChildTaskqueue.registerWorkflowImplementationFactory(
        ChildWorkflow.class,
        () -> {
          ChildWorkflow child = mock(ChildWorkflow.class);
          return child;
        });

  Note that the taskqueue for the worker running the child workflow in your case will be different (not "child-taskqueue")

or you can get the workflow history of the parent workflow and look for the eventType = ChildWorkflowExecutionStarted

    assertTrue(
        testWorkflowRule
            .getTestEnvironment()
            .getWorkflowExecutionHistory(execution)
            .getHistory()
            .getEventsList()
            .stream()
            .anyMatch(f -> f.hasChildWorkflowExecutionStartedEventAttributes()));

Let me know how it goes,
Antonio