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IBM WebSphere eXtreme Scale 6 by Anthony Chaves

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Removal versus eviction

Setting an eviction policy on a BackingMap makes more sense now that we're using a Loader. Imagine that our cache holds only a fraction of the total data stored in the database. Under heavy load, the cache is constantly asked to hold more and more data, but it operates at capacity. What happens when we ask the cache to hold on to one more payment? The BackingMap needs to remove some payments in order to make room for more.

BackingMaps have three basic eviction policies: LRU (least-recently used), LFU (least-frequently used), and TTL (time-to-live). Each policy tells the BackingMap which objects should be removed in order to make room for more. In the event that an object is evicted from the cache, its status in the database ...

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