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https://issues.jboss.org/browse/ISPN-1300?page=com.atlassian.jira.plugin....
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Johann Burkard commented on ISPN-1300:
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Sorry for digging this one up but I tried setting the maximum number of buckets to 4096
(for an ext3 file system) and that made Infinispan infinitely slower. When this is
configurable, could this be done in a way that's free of side-effects?
Reduce number of locks and buckets generated by
BucketBasedCacheStore
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Key: ISPN-1300
URL:
https://issues.jboss.org/browse/ISPN-1300
Project: Infinispan
Issue Type: Enhancement
Components: Configuration, Loaders and Stores
Affects Versions: 5.0.0.CR8
Reporter: Robert Stupp
Assignee: Manik Surtani
Fix For: 5.0.0.FINAL
The current implementation of FileCacheStore creates one bucket and lock for each hash
key - which results in up to 4.2 billion files (2^32).
It should limit the number of files to
a) improve performance of purge
b) reduce number of open file handles (system resources)
c) reduce number of Java objects/heap (JVM resources)
d) improve performance
The implementation allows us to do so.
Only 4 lines of code are necessary in BucketBasedCacheStore implementation:
{code}
private int hashKeyMask = 0xfffffc00; // TODO should get a configuration entry
@Override
protected Integer getLockFromKey(Object key) {
return Integer.valueOf(key.hashCode() & hashKeyMask);
}
{code}
This reduces the number of files to 2^22 = 4,194,304 files. Since each application and
each cache store has different semantics the hasKeyMask value should be configurable -
best would be to configure the number of bits.
Side effect: If someone changes the FileCacheStore hasKeyMask, the whole cache store
becomes unuseable. So I opened another enhancement ...
Note: This implementation should be used in a different class (e.g. extend
FileCacheStore) because it makes existing file cache stores unusable.
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