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https://issues.apache.org/jira/browse/KAFKA-8020?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Richard Yu updated KAFKA-8020:
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Description: In distributed systems, time-aware LRU Caches offer a superior
eviction policy then tradition LRU models, having more cache hits than misses.
In this new policy, if an item which is stored beyond its useful lifespan, then
it is removed. For example, in {{CachingWindowStore}}, a window usually is of
limited size. After it expires, it would no longer be queried for, but it
potentially could stay in the ThreadCache for an unnecessary amount of time if
it is not evicted (i.e. the number of entries being inserted is few). For
better allocation of memory, it would be better if we implement a time-aware
LRU Cache which takes into account the lifespan of an entry and removes it once
it has expired. (was: Currently, in Kafka Streams, ThreadCache is used to
store {{InternalProcessorContext}}s. Typically, an entry is only needed for a
certain interval of time. For example, in {{CachingWindowStore}}, a window is
of fixed size. After it expires, it would no longer be queried for, but it
potentially could stay in the ThreadCache for an unnecessary amount of time if
it is not evicted (i.e. the number of entries being inserted is few). For
better allocation of memory, it would be better if we implement a time-aware
LRU Cache which takes into account the lifespan of an entry and removes it once
it has expired.)
> Consider making ThreadCache a time-aware LRU Cache
> --------------------------------------------------
>
> Key: KAFKA-8020
> URL: https://issues.apache.org/jira/browse/KAFKA-8020
> Project: Kafka
> Issue Type: Improvement
> Components: streams
> Reporter: Richard Yu
> Priority: Major
>
> In distributed systems, time-aware LRU Caches offer a superior eviction
> policy then tradition LRU models, having more cache hits than misses. In this
> new policy, if an item which is stored beyond its useful lifespan, then it is
> removed. For example, in {{CachingWindowStore}}, a window usually is of
> limited size. After it expires, it would no longer be queried for, but it
> potentially could stay in the ThreadCache for an unnecessary amount of time
> if it is not evicted (i.e. the number of entries being inserted is few). For
> better allocation of memory, it would be better if we implement a time-aware
> LRU Cache which takes into account the lifespan of an entry and removes it
> once it has expired.
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