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Arpit Agarwal commented on HDFS-11789: -------------------------------------- Thanks for updating the patch [~hanishakoneru]. A few comments: # Typos in {{SHORT_CIRCUIT_READ_LATECNY_METRIC_REGISTERD_NAME}}. # The test-only method {{getShortCircuitReadRollingAverages}} should be tagged with {{\@VisibleForTesting}}. # I think we can eliminate the METRICS_SAMPLING_PERCENTAGE_KEY config key. We can enable the metric when the sampling percentage is > 0. # Let's avoid static initialization of {{BlockReaderLocal#metrics}}. One issue is that adding the overhead of a MutableRollingAverages object (and its rates roller thread) for all clients, most of which may will never enable SCR statistics. I think your original approach of initializing it within a lock on construction was fine, the overhead of that lock compared to the overhead of cloning a file descriptor via system calls should be minimal. Still reviewing the tests. > Maintain Short-Circuit Read Statistics > -------------------------------------- > > Key: HDFS-11789 > URL: https://issues.apache.org/jira/browse/HDFS-11789 > Project: Hadoop HDFS > Issue Type: Improvement > Components: hdfs-client > Reporter: Hanisha Koneru > Assignee: Hanisha Koneru > Attachments: HDFS-11789.001.patch, HDFS-11789.002.patch > > > If a disk or controller hardware is faulty then short-circuit read requests > can stall indefinitely while reading from the file descriptor. Currently > there is no way to detect when short-circuit read requests are slow or > blocked. > This Jira proposes that each BlockReaderLocal maintain read statistics while > it is active by measuring the time taken for a pre-determined fraction of > read requests. These per-reader stats can be aggregated into global stats > when the reader is closed. The aggregate statistics can be exposed via JMX. -- This message was sent by Atlassian JIRA (v6.4.14#64029) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org