High latency can cause get_task_stream() to miss tasks #9253

#!/usr/bin/env python
from dask.distributed import Client


def main():
    with Client() as client:

        # FIXME: The program succeeds only when this line is active.
        # tasks = client.get_task_stream()

        # Submit dummy task.
        client.submit(lambda: True).result()

        # Inquire tasks and validate the submitted task has been run.
        tasks = client.get_task_stream()
        if not tasks:
            raise RuntimeError("No tasks have been recorded")
        task = tasks[-1]
        assert task["key"].startswith("lambda"), f"Task has wrong key: {task['key']}"
        assert task["status"] == "OK", f"Task status not OK: {task['status']}"
        print("SUCCESS")


if __name__ == "__main__":
    main()