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Feng Honghua commented on HBASE-10263: -------------------------------------- [~yuzhih...@gmail.com]: bq.Is the above variable used(inMemoryForceMode) ? ==> No, they(together with single/multi/memory factors) are not used. There is a historical reason for these variables here: this flag(and other 3 factors) will be read from *conf* passed as parameter in LruBlockCache constructor, in 0.94.3(our internal branch) there is a INFO log for max-size before constructing the LruBlockCache, and I added these 'forceMode/single/multi/memory' info in that INFO log as well, they are used just for info purpose, but this INFO log in CacheConfig.java doesn't exist in trunk code(it's removed), and I forgot to remove these four just-for-info variables accordingly. *It won't affect correctness*. Thanks for point this out :-) > make LruBlockCache single/multi/in-memory ratio user-configurable and provide > preemptive mode for in-memory type block > ---------------------------------------------------------------------------------------------------------------------- > > Key: HBASE-10263 > URL: https://issues.apache.org/jira/browse/HBASE-10263 > Project: HBase > Issue Type: Improvement > Reporter: Feng Honghua > Assignee: Feng Honghua > Attachments: HBASE-10263-trunk_v0.patch > > > currently the single/multi/in-memory ratio in LruBlockCache is hardcoded > 1:2:1, which can lead to somewhat counter-intuition behavior for some user > scenario where in-memory table's read performance is much worse than ordinary > table when two tables' data size is almost equal and larger than > regionserver's cache size (we ever did some such experiment and verified that > in-memory table random read performance is two times worse than ordinary > table). > this patch fixes above issue and provides: > 1. make single/multi/in-memory ratio user-configurable > 2. provide a configurable switch which can make in-memory block preemptive, > by preemptive means when this switch is on in-memory block can kick out any > ordinary block to make room until no ordinary block, when this switch is off > (by default) the behavior is the same as previous, using > single/multi/in-memory ratio to determine evicting. > by default, above two changes are both off and the behavior keeps the same as > before applying this patch. it's client/user's choice to determine whether or > which behavior to use by enabling one of these two enhancements. -- This message was sent by Atlassian JIRA (v6.1.5#6160)