[jira] [Created] (SAMZA-2118) Improve the shutdown sequence of AsyncRunLoop.

["Shanthoosh Venkataraman (JIRA)" <ji...@apache.org>]

Shanthoosh Venkataraman created SAMZA-2118:
----------------------------------------------

             Summary: Improve the shutdown sequence of AsyncRunLoop.
                 Key: SAMZA-2118
                 URL: https://issues.apache.org/jira/browse/SAMZA-2118
             Project: Samza
          Issue Type: Improvement
            Reporter: Shanthoosh Venkataraman
            Assignee: Shanthoosh Venkataraman


A samza container is comprised of multiple tasks and event-loop. Event loop is the main orchestration layer between the different stages of a task(process, commit, window) and delivers messages to task after polling from live consumers.  

Currently in samza, the event loop dispatches messages to the tasks as per user-defined configuration `task.max.concurrency`. After dispatching messages with count equal to `task.max.concurrency` to the tasks,  the event loop is blocked until the processing of at-least a single dispatched message finishes(aka the task implementation invokes `taskCallBack.complete()` for at-least a message). 

When the event loop is blocked by this, the user thread would sometimes try to shutdown the event loop. This shutdown intent marked by the user-thread will take effect only when the processing of a single message completes. In some-cases, when the task implementation does retry on failure for a message,  this could prolong the shutdown of the samza event loop. 

This introduces tight coupling between the task processing time and the event loop shutdown time. This behavior was observed predominantly in standalone application where the samza container is shutdown as a part of the re-balancing phase. 

To alleviate this problem, as a part of this ticket, we propose to wake-up the samza event-loop thread when the user-thread marks the intent to shutdown the event-loop.



--
This message was sent by Atlassian JIRA
(v7.6.3#76005)