Andrew Purtell created HBASE-12117:
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Summary: Constructors that use Configuration may be harmful
Key: HBASE-12117
URL: https://issues.apache.org/jira/browse/HBASE-12117
Project: HBase
Issue Type: Improvement
Reporter: Andrew Purtell
Attachments: traces.client.c.svg, traces.client.getHTable.svg
There's a common pattern in HBase code where in the constructor, or in an
initialization method also called once per instantiation, or both, we look up
values from Hadoop Configuration and store them into fields. This can be
expensive if the object is frequently created. Configuration is a heavyweight
registry that does a lot of string operations and regex matching. See attached
example. Method calls into Configuration account for 48.25% of CPU time when
creating the HTable object in 0.98. (The remainder is spent instantiating the
RPC controller via reflection, a separate issue that merits followup
elsewhere.) HConnections Creation of HTable instances is expected to be a
lightweight operation if a client is using unmanaged HConnections. However
creating HTable instances takes up about 18% of total on CPU time. This is just
one example where constructors that use Configuration may be harmful.
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