[HDFS-15745] Make DataNodePeerMetrics#LOW_THRESHOLD_MS and MIN_OUTLIER_DETECTION_NODES configurable - ASF JIRA

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Details

Type: Improvement
Status: Resolved
Priority: Major
Resolution: Fixed
Affects Version/s: 3.4.0, 3.3.5
Fix Version/s: 3.4.0, 3.3.5
Component/s: datanode, metrics
Labels:
- pull-request-available

Target Version/s:

3.4.0, 3.3.5
Hadoop Flags:

Reviewed

Description

When i enable DataNodePeerMetrics to find slow slow peer in cluster, i found there is a lot of slow peer but ReportingNodes's averageDelay is very low, and these slow peer node are normal. I think the reason of why generating so many slow peer is that the value of DataNodePeerMetrics#LOW_THRESHOLD_MS is too small (only 5ms) and it is not configurable. The default value of slow io warning log threshold is 300ms, i.e. DFSConfigKeys.DFS_DATANODE_SLOW_IO_WARNING_THRESHOLD_DEFAULT = 300, so DataNodePeerMetrics#LOW_THRESHOLD_MS should not be less than 300ms, otherwise namenode will get a lot of invalid slow peer information.