Wei-Chiu Chuang created HDFS-14276:
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Summary: [SBN read] Reduce tailing overhead
Key: HDFS-14276
URL: https://issues.apache.org/jira/browse/HDFS-14276
Project: Hadoop HDFS
Issue Type: Improvement
Components: ha, namenode
Affects Versions: 3.3.0
Environment: Hardware: 4-node cluster, each node has 4 core, Xeon
2.5Ghz, 25GB memory.
Software: CentOS 7.4, CDH 6.0 + Consistent Reads from Standby, Kerberos, SSL,
RPC encryption + Data Transfer Encryption.
Reporter: Wei-Chiu Chuang
Assignee: Wei-Chiu Chuang
Attachments: Screen Shot 2019-02-12 at 10.51.41 PM.png
When Observer sets {{dfs.ha.tail-edits.period}} = {{0ms}}, it tails edit log
continuously in order to fetch the latest edits, but there is a lot of overhead
in doing so.
Critically, edit log tailer should _not_ update NameDirSize metric every time.
It has nothing to do with fetching edits, and it involves lots of directory
space calculation.
Profiler suggests a non-trivial chunk of time is spent for nothing.
Other than this, the biggest overhead is in the communication to
serialize/deserialize messages to/from JNs. I am looking for ways to reduce the
cost because it's burning 30% of my CPU time even when the cluster is idle.
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