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From "Josh Elser (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HBASE-18133) Low-latency space quota size reports
Date Tue, 30 May 2017 15:11:04 GMT
Josh Elser created HBASE-18133:

             Summary: Low-latency space quota size reports
                 Key: HBASE-18133
                 URL: https://issues.apache.org/jira/browse/HBASE-18133
             Project: HBase
          Issue Type: Improvement
            Reporter: Josh Elser
            Assignee: Josh Elser

Presently space quota enforcement relies on RegionServers sending reports to the master about
each Region that they host. This is done by periodically, reading the cached size of each
HFile in each Region (which was ultimately computed from HDFS).

This means that the Master is unaware of Region size growth until the the next time this chore
in a RegionServer fires which is a fair amount of latency (a few minutes, by default). Operations
like flushes, compactions, and bulk-loads are delayed even though the RegionServer is running
those operations locally.

Instead, we can create an API which these operations could invoke that would automatically
update the size of the Region being operated on. For example, a successful flush can report
that the size of a Region increased by the size of the flush. A compaction can subtract the
size of the input files of the compaction and add in the size of the resulting file.

This de-couples the computation of a Region's size from sending the Region sizes to the Master,
allowing us to send reports more frequently, increasing the responsiveness of the cluster
to size changes.

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