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Remove MediatedEvictionConcurrentHashMap. #187
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Use a regular ConcurrentHashMap. release() operations that return the final lease are responsible for eviction to disk. The node remains in the cache with a lease count of -1 this is used as a tombstone in the cache while the eviction to disk is taking place.
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Is the implication of this that the node cache will always miss unless there is enough contention between threads? |
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Err. Performance numbers show a 10x reduction in performance for one class of critical jobs. |
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Closing for now, as it does not seem safe to become the default (and only) option at this time. Might make an interesting toggle. |
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Use a regular ConcurrentHashMap. release() operations that return the final lease are responsible for eviction to disk. The node remains in the cache with a lease count of -1 this is used as a tombstone
in the cache while the eviction to disk is taking place.
Thanks to an earlier change where nodes must be leased prior to deletion, I don't think there is the possibility of a race condition with node deletion and node eviction. Also note that node state "-3" has been removed in this branch. It is no longer needed.
In the performance tests this branch performance no worse and sometimes slightly better than the MediatedEvictionConcurrentHashMap. Results are https://goo.gl/yk2ztF (internal access only).