OpenBitSet can allocate more bytes than it needs
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Key: CASSANDRA-3618
URL: https://issues.apache.org/jira/browse/CASSANDRA-3618
Project: Cassandra
Issue Type: Bug
Components: Core
Affects Versions: 1.0.0
Reporter: Sylvain Lebresne
Assignee: Sylvain Lebresne
Fix For: 1.0.7
CASSANDRA-2466 changed OpenBitSet to break big long arrays into pages. However,
it always allocate full pages, each page being of size 4096 * 8 bytes. This
means that we almost always allocate too much bytes, and for a row that has 1
column, the associated row bloom filter allocates 32760 more bytes than it
should.
This has a significant impact on performance. In a small test using the
SSTableSimpleUnsortedWriter to generate rows with 1 column, 0.8 is about twice
as fast as 1.0 because of that (the difference shrink when there is more
columns obviously).
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