[jira] [Created] (HDFS-14997) BPServiceActor process command from NameNode asynchronously

["Xiaoqiao He (Jira)" <ji...@apache.org>]

Xiaoqiao He created HDFS-14997:
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             Summary: BPServiceActor process command from NameNode asynchronously
                 Key: HDFS-14997
                 URL: https://issues.apache.org/jira/browse/HDFS-14997
             Project: Hadoop HDFS
          Issue Type: Improvement
          Components: datanode
            Reporter: Xiaoqiao He
            Assignee: Aiphago


There are two core functions, report(#sendHeartbeat, #blockReport, #cacheReport) and #processCommand in #BPServiceActor main process flow. If processCommand cost long time it will block send report flow. Meanwhile processCommand could cost long time(over 1000s the worst case I meet) when IO load  of DataNode is very high. Since some IO operations are under #datasetLock, So it has to wait to acquire #datasetLock long time when process some of commands(such as #DNA_INVALIDATE). In such case, #heartbeat will not send to NameNode in-time, and trigger other disasters.
I propose to improve #processCommand asynchronously and not block #BPServiceActor to send heartbeat back to NameNode when meet high IO load.
Notes:
1. Lifeline could be one effective solution, however some old branches are not support this feature.
2. IO operations under #datasetLock is another issue, I think we should solve it at another JIRA.



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