Wang, Xinglong created HBASE-18764:
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Summary: add slow read block log entry to alert slow datanodeinfo
when reading a block
Key: HBASE-18764
URL: https://issues.apache.org/jira/browse/HBASE-18764
Project: HBase
Issue Type: Improvement
Components: HFile
Affects Versions: 1.1.12
Reporter: Wang, Xinglong
Priority: Minor
HBASE is on top of HDFS and both are distributed system. HBASE will also get
impacted when there is struggler datanode due to network/disk/cpu issue. All
HBASE read/scan towards that datanode will be slowdown. It's not easy for hbase
admin to find out the struggler datanode in such case.
While we have a log entry known as slow sync. One such entry is like the
following. It will help hbase admin to quickly identify the slow datanode in
the pipline in case of network/disk/cup issue with one of the 3 datanods in
pipeline.
{noformat}
2017-07-08 19:11:30,538 INFO [sync.3] wal.FSHLog: Slow sync cost: 490189 ms,
current pipeline:
[DatanodeInfoWithStorage[xx.xx.xx.xx:50010,DS-c391299a-aa9f-4146-ac7e-a493ae536bff,DISK],
DatanodeInfoWithSt
orage[xx.xx.xx.xx:50010,DS-21a85f8b-f389-4f9e-95a8-b711945fd210,DISK],
DatanodeInfoWithStorage[xx.xx.xx.xx:50010,DS-aa48cef2-3554-482f-b49d-be4763f4d8b8,DISK]]
{noformat}
Inspired by slow sync log entry, I think it will also be beneficial for us to
print out such kind of entry when we encounter slow read case. So that it will
be easy to identify the slow datanode.
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