Tak-Lon (Stephen) Wu created HBASE-26274:
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Summary: Create an option to reintroduce BlockCache to mapreduce
job
Key: HBASE-26274
URL: https://issues.apache.org/jira/browse/HBASE-26274
Project: HBase
Issue Type: Bug
Components: BlockCache, HFile, mapreduce
Affects Versions: 2.4.6, 3.0.0-alpha-1
Reporter: Tak-Lon (Stephen) Wu
In HBASE-21498 (see [this
commit|https://github.com/apache/hbase/commit/27a0f205c52f83fe7500ee2ffc6cf6582f565a63#diff-8a3e39e6df1afe47811fc17702da598fe0d80496d66e579bea4bd224c6d8da03R218],
it change the behavior that only region server can initialize on-heap
BlockCache/LruBlockCache, this should be the right change for HMaster.
Other downstream dependency that uses getScanner from a file-based region and
read HStore/HFile lost the BlockCache for caching INDEX/LEAF_INDEX (at least
still a problem with HBase-2.4) after this change (it worked before) and caused
performance impact with 2x slower.
One way to bring back the performance is to allow non-RS and non-HMaster can
use a compact version of blockcache with smaller memory and less hbase internal
configuration.
Or if we can find a way to cache or skip reading the same {{LEAF_INDEX}} when
scanning the DATA block with HFile.
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