Anoop Sam John created HBASE-14186:
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Summary: Read mvcc vlong optimization
Key: HBASE-14186
URL: https://issues.apache.org/jira/browse/HBASE-14186
Project: HBase
Issue Type: Sub-task
Reporter: Anoop Sam John
Assignee: Anoop Sam John
Fix For: 2.0.0
{code}
for (int idx = 0; idx < remaining; idx++) {
byte b = blockBuffer.getByteAfterPosition(offsetFromPos + idx);
i = i << 8;
i = i | (b & 0xFF);
}
{code}
Doing the read as in case of BIG_ENDIAN.
After HBASE-12600, we tend to keep the mvcc and so byte by byte read looks
eating up lot of CPU time. (In my test HFileReaderImpl#_readMvccVersion comes
on top in terms of hot methods). We can optimize here by reading 4 or 2 bytes
in one shot when the length of the vlong is more than 4 bytes. We will in turn
use UnsafeAccess methods which handles ENDIAN.
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