Bryan Beaudreault created HBASE-27531:
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Summary: AsyncRequestFutureImpl unnecessarily clears meta cache
for full server
Key: HBASE-27531
URL: https://issues.apache.org/jira/browse/HBASE-27531
Project: HBase
Issue Type: Improvement
Reporter: Bryan Beaudreault
In AsyncRequestFutureImpl.receiveGlobalFailure, the meta cache is cleared
twice. First the entire cache is cleared for the serverName, then each
individual region's cache is further cleared. See
[here.|https://github.com/apache/hbase/blob/branch-2/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncRequestFutureImpl.java#L766-L780]
This behavior was introduced in HBASE-19900, which was a Jira more related to
return value corruption rather than meta cache. I believe the change was an
accident in the refactoring. Take a look at the commit
[here.|https://github.com/apache/hbase/commit/e2636c81f7700a34368d73079375dbce6e180547#diff-7c58ffd83c150488599591ed5a3a068599646ebdbbbfdcd2233386e5472cca35L709]
In the commit, the cleanServerCache call should have been wrapped in tableName
== null. Then the updateCachedLocations call should have been wrapped in
tableName != null. So we should only go down one path or another based on the
existence of a tableName.
Full server cache clears are extremely expensive in a high concurrency client.
This is especially true in AsyncProcess, where a single request might hit many
servers. We should reinstate the tableName checks so that we only do one or the
other.
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