Time management service refuses processing interaction

[Cheng-Yuan-0124]

Hi,

Currently, I am trying to integrate the MOSAIC with CARLA simulator. The integration of ambassador and interaction have been implemented but there is an issue I am encountering. When the function receiveInteraction in the AbstractFederateAmbassador script successfully adds my interaction into the interactionQueue, the time management service refuses or ignores my interaction sometimes. This kind of issue happening randomly in a run. Sometimes happening after running several hours, sometimes happening within few minutes or sometimes never happening in a run. This issue cause the simulation freezing because my script can not receive the repose of the request interaction. Is there any clue or any part I could check to deal with it?

Thank you very much

[kschrab]

Hi, this is rather hard to debug for us. I could only thing of interactions having outdated timestamps. Did you make sure that MOSAIC RTI is controlling the simulation time in Carla and not vice-versa? Have you tried to step trough the RTI for debugging, e.g., through AbstractFederateAmbassador#receiveInteraction?`

Nevertheless, we also working on a coupling with CARLA and hope to release a initial version of it at the end of the year.

[Cheng-Yuan-0124]

Hi, thanks for the replying. I've found the issue causing simulation freezing at the end which is exact coming from SequentialTimeManagement. The issue is when two of the federate events in the EfficientPriorityQueue with same lookahead, priority and requestedTime, they will be sorted by the federateId (or other variables). The picture below shows the situation I mention, the federateId carla will be the next event to be polled from the queue but it will be always added back to the queue at the first index which is prior than the sumo federateId. As a result, the sumo federateId will never be processed then causing freezing. Do you have any idea about how to properly deal with this situation or is there anything I did in the wrong way? Thanks!

.

[kschrab]

Which of both events should be executed at first? Have you already tried passing a higher priority than 2 when calling rti.requestAdvanceTime(time, lookahead, priority) from your CarlaAmbassador/Federate?

[Cheng-Yuan-0124]

In the case I mention above, the interactionQueue in CARLA ambassador doesn't have any data so the first event should be executed is sumo federate event. I've tried passing a higher priority from my CarlaAmbassador but it will have kind of the same freezing situation when first event should be CARLA but stuck in sumo federate event because the interactionQueue in SUMO ambassador is empty. The current solution I have is adding 1 nano second such as rti.requestAdvanceTime(time + executeTimes, lookahead, priority) in CarlaAmbassador which executeTimes equals to 0 at beginning but being counted when requestAdvanceTime being processed and reset it when CarlaAmbassador received the respond, then the CARLA federate event will not be added back to the first index in the event queue.

I am not sure it is or not a correct way to use MOSAIC, hope you could give me some advise such as how you handling this situation when you are implementing the CARLA coupling work