[HBASE-8868] add metric to report client shortcircuit reads - ASF JIRA

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Details

Type: Improvement
Status: Closed
Priority: Minor
Resolution: Fixed
Affects Version/s: 0.94.8, 0.95.1
Fix Version/s: 3.0.0-alpha-1, 2.3.0, 1.7.0, 2.2.5
Component/s: metrics, regionserver
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Release Note:

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Expose file system level read metrics for RegionServer.

If the HBase RS runs on top of HDFS, calculate the aggregation of
ReadStatistics of each HdfsFileInputStream. These metrics include:
(1) total number of bytes read from HDFS.
(2) total number of bytes read from local DataNode.
(3) total number of bytes read locally through short-circuit read.
(4) total number of bytes read locally through zero-copy read.

Because HDFS ReadStatistics is calculated per input stream, it is not
feasible to update the aggregated number in real time. Instead, the
metrics are updated when an input stream is closed.

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Expose file system level read metrics for RegionServer. If the HBase RS runs on top of HDFS, calculate the aggregation of ReadStatistics of each HdfsFileInputStream. These metrics include: (1) total number of bytes read from HDFS. (2) total number of bytes read from local DataNode. (3) total number of bytes read locally through short-circuit read. (4) total number of bytes read locally through zero-copy read. Because HDFS ReadStatistics is calculated per input stream, it is not feasible to update the aggregated number in real time. Instead, the metrics are updated when an input stream is closed.
Tags:
metrics

Description

With the availability of shortcircuit reads, when the feature is enabled there is no metric which exposes how many times the regionserver was able to shortcircuit the read and not make a IPC to the datanode.

It will be great to add the metric and expose it via Ganglia.