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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