HDFS-17805. Separate flushNanos and syncNanos in flushOrSync slow log#8315
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balodesecurity wants to merge 1 commit intoapache:trunkfrom
Open
HDFS-17805. Separate flushNanos and syncNanos in flushOrSync slow log#8315balodesecurity wants to merge 1 commit intoapache:trunkfrom
balodesecurity wants to merge 1 commit intoapache:trunkfrom
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Problem
In
BlockReceiver.flushOrSync(), flush and sync durations are accumulated into a singleflushTotalNanoscounter. When the total duration exceeds the slow-IO threshold, the WARN log only reports the combined value:This makes it impossible to tell whether the latency originates from the flush step or the fsync step, hindering production diagnosis.
Fix
Track flush and sync durations in separate counters (
flushTotalNanos,syncTotalNanos). The slow-IO WARN log now reports them independently:This lets operators immediately determine whether a bottleneck is in the page-cache flush or the disk fsync.
Testing
TestBlockReceiverSlowLog#testFlushOrSyncSlowLogContainsSeparateFlushAndSyncNanos: starts a single-DN MiniDFSCluster with slow-IO threshold set to 0 ms (triggers the log on every call), writes a file and callshsync(), captures the WARN log output, and asserts bothflushNanos=andsyncNanos=are present.