Kihwal Lee created HDFS-8046:
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Summary: Allow better control of getContentSummary
Key: HDFS-8046
URL: https://issues.apache.org/jira/browse/HDFS-8046
Project: Hadoop HDFS
Issue Type: Bug
Reporter: Kihwal Lee
On busy clusters, users performing quota checks against a big directory
structure can affect the namenode performance. It has become a lot better after
HDFS-4995, but as clusters get bigger and busier, it is apparent that we need
finer grain control to avoid long read lock causing throughput drop.
Even with unfair namesystem lock setting, a long read lock (10s of
milliseconds) can starve many readers and especially writers. So the locking
duration should be reduced, which can be done by imposing a lower
count-per-iteration limit in the existing implementation. But HDFS-4995 came
with a fixed amount of sleep between locks. This needs to be made configurable,
so that {{getContentSummary()}} doesn't get exceedingly slow.
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