[jira] [Created] (REEF-1403) Deadlock between ContextRuntime.StartTask and HeartBeatManager.OnNext(Alarm)

["Mariia Mykhailova (JIRA)" <ji...@apache.org>]

Mariia Mykhailova created REEF-1403:
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             Summary: Deadlock between ContextRuntime.StartTask and HeartBeatManager.OnNext(Alarm)
                 Key: REEF-1403
                 URL: https://issues.apache.org/jira/browse/REEF-1403
             Project: REEF
          Issue Type: Bug
          Components: REEF.NET Evaluator
            Reporter: Mariia Mykhailova


We have a potential deadlock in task start/timed heartbeats.

{{ContextRuntime.StartTask}} does the following:
1. Acquires lock on {{ContextRuntime._contextLifeCycle}}
2. Calls {{TaskRuntime.RunTask()}} which calls {{TaskStatus.setInit}} which calls {{HeartBeatManager.onNext(TaskStatusProto)}} which acquires lock on {{HeartBeatManager}} itself.

At the same time {{HeartBeatManager.onNext(Alarm)}} gets called every 4 seconds since evaluator start, and it:
1. Acquires lock on {{HeartBeatManager}}.
2. Calls {{GetEvaluatorHeartbeatProto}} which calls {{ContextManager.GetTaskStatus()}} which calls {{ContextManager.GetTaskStatus()}} which acquires lock on {{ContextRuntime._contextLifeCycle}}.

If task will be starting at the same time as heartbeat kick in, these two actions will deadlock each other. I encountered a repro on our tests when working on REEF-1388, but in general case it's not impossible that second or third task that starts on evaluator runs into a heartbeat.



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