BloomFilter's use of BitSet is too inefficient
----------------------------------------------
Key: HBASE-1246
URL: https://issues.apache.org/jira/browse/HBASE-1246
Project: Hadoop HBase
Issue Type: Bug
Affects Versions: 0.20.0
Environment: Java 1.6, OSX 64 bit
Reporter: ryan rawson
Fix For: 0.20.0
>From the logfile run of TestBloomFilter with special SizeOf agent jar:
Writing bloom filter for:
hdfs://localhost:64003/user/ryan/testComputedParameters/1278366260/contents/6159869037185296839
for size: 100
2009-03-06 01:54:25,491 DEBUG [RegionServer:0.cacheFlusher]
regionserver.StoreFile$StoreFileWriter(319): New bloom filter: vectorSize: 1175
hash_count: 5 numKeys: 100
Serialized bloomfilter size: 160
In memory bf size: 1248
As we can see, the bit vector is 1175 bits, and the serialized size is fairly
compact - 160 bytes.
But the in-memory size is nearly 10x bigger than it has to be. Looking in
BloomFilter we see:
BitSet bits;
is the only field.
Clearly it seems the BitSet is using 1 byte = 1 bit. That is an 8 time
expansion of where we should be.
Considering every HFile could potentially have a bloom filter, and bloom
filters are more likely to have bit vector sizes of 10,000-100,000, we should
do something about this. Aka: write our own bit-set that uses byte[] and bit
ops.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
