locust

Locust: event for master when a new worker joins

When using locust in distributed mode, is there an event that would allow the master node to detect whenever a new worker joins, and send it a message?

We currently use @events.test_start.add_listener as described in this snippet from the locust documentation

@events.test_start.add_listener
def on_test_start(environment, **_kwargs):
    if not isinstance(environment.runner, WorkerRunner):
        users = [
            {"name": "User1"},
            {"name": "User2"},
            {"name": "User3"},
        ]
        environment.runner.send_message('test_users', users)

However, this is only the "test_start" event. We're looking to cover cases where new workers join randomly afterwards.

Thanks

Solution

  • A worker_connect event was added in locust 2.16.0!

    https://github.com/locustio/locust/pull/2344

    It is a little bit complicated to use though, because the worker may not be ready to receive any custom messages when it happens (the worker hasnt had a chance to trigger any other events, like init).