Tommy Becker created SAMZA-812:
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Summary: CachedStore flushes too often
Key: SAMZA-812
URL: https://issues.apache.org/jira/browse/SAMZA-812
Project: Samza
Issue Type: Bug
Components: kv
Affects Versions: 0.10.0, 0.9.1
Reporter: Tommy Becker
The CachedStore wrapper class flushes on every put or putAll that dirties the
cache. This seems rooted in a misunderstanding of
LinkedHashMap.removeEldestEntry. This method is called on every put() or
putAll() to the map, and the implementation in CachedStore flushes the dirty
entries without first checking if the cache is at capacity. Interestingly,
fixing this issue reveals another in
org.apache.samza.storage.kv.TestKeyValueStores#putAndGet. This test
unintentionally relies on the inefficient behavior in CachedStore to handle
array keys. Specifically, even though different array instances can never get
cache hits due to pass-by-reference semantics in the cache, the existing
flushing behavior causes the arrays to get prematurely written to the store
which has pass-by-value semantics.
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