MultiProcess executor not working as expected

[giuliohome]

What are you really trying to do?

This is a follow up to this message, in particular I'm simply running this official sample https://github.com/temporalio/samples-python/blob/main/hello/hello_activity_multiprocess.py

Describe the bug

I see this output

(.venv) C:\Users\giulio365cloud\dev-test>python multiprocessor_giulio.py
Heartbeating activity on PID 5104
Heartbeating activity on PID 5104
Heartbeating activity on PID 5104
Heartbeating activity on PID 5104
Heartbeating activity on PID 5104
Heartbeating activity on PID 5104
Result on PID 7072: Hello, World from activity on PID 5104! and then Hello, World from activity on PID 5104!

I would have expected to see a different PID when the activity runs the second time!

Minimal Reproduction

I have taken the official sample and simply repeated the activity execution two times inside the workflow

@workflow.defn
class GreetingWorkflow:
    @workflow.run
    async def run(self, name: str) -> str:
        ret1 = await workflow.execute_activity(
            compose_greeting,
            ComposeGreetingInput("Hello", name),
            start_to_close_timeout=timedelta(seconds=10),
            # Always set a heartbeat timeout for long-running activities
            heartbeat_timeout=timedelta(seconds=2),
        )
        ret2 = await workflow.execute_activity(
            compose_greeting,
            ComposeGreetingInput("Hello", name),
            start_to_close_timeout=timedelta(seconds=10),
            # Always set a heartbeat timeout for long-running activities
            heartbeat_timeout=timedelta(seconds=2),
        )
        return ret1 + " and then " + ret2

and I have also modified the activity to print its PID in the hello message

@activity.defn
def compose_greeting(input: ComposeGreetingInput) -> str:
    # We'll wait for 3 seconds, heartbeating in between (like all long-running
    # activities should do), then return the greeting
    for _ in range(0, 3):
        print(f"Heartbeating activity on PID {os.getpid()}")
        activity.heartbeat()
        time.sleep(1)
    return f"{input.greeting}, {input.name} from activity on PID {os.getpid()}!"

Environment/Versions

• OS and processor: Windows 11 Enterprise 16 vCPU 32 GB RAM Device name Windows11Pro Processor Intel(R) Xeon(R) Platinum 8370C CPU @ 2.80GHz 2.79 GHz Installed RAM 32.0 GB System type 64-bit operating system, x64-based processor

• Temporal Version: Latest temporal version, latest SDK version temporal server start-dev CLI 1.1.0 (Server 1.25.0, UI 2.30.3)

• Are you using Docker or Kubernetes or building Temporal from source? Nope

[giuliohome]

Uhm ... I see... they need to run in parallel

@workflow.defn
class GreetingWorkflow:
    @workflow.run
    async def run(self, name: str) -> str:
        task1 = asyncio.create_task( workflow.execute_activity(
            compose_greeting,
            ComposeGreetingInput("Hello", name),
            start_to_close_timeout=timedelta(seconds=10),
            # Always set a heartbeat timeout for long-running activities
            heartbeat_timeout=timedelta(seconds=2),
        ))
        task2 = asyncio.create_task( workflow.execute_activity(
            compose_greeting,
            ComposeGreetingInput("Hello", name),
            start_to_close_timeout=timedelta(seconds=10),
            # Always set a heartbeat timeout for long-running activities
            heartbeat_timeout=timedelta(seconds=2),
        ) )
        ret1 = await task1
        ret2 = await task2
        return ret1 + " and then " + ret2

in that case

python multiprocessor_giulio.py
Heartbeating activity on PID 4952
Heartbeating activity on PID 5904
Heartbeating activity on PID 4952
Heartbeating activity on PID 5904
Heartbeating activity on PID 4952
Heartbeating activity on PID 5904
Result on PID 11484: Hello, World from activity on PID 4952! and then Hello, World from activity on PID 5904!