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https://issues.apache.org/jira/browse/HBASE-16287?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Anoop Sam John updated HBASE-16287:
-----------------------------------
Release Note:
In order to avoid blockcache size exceed acceptable size too much, we add one
configuration "hbase.lru.blockcache.hard.capacity.limit.factor" to decide
whether the block could be put into LruBlockCache or not. This factor defaults
to 1.2
If blockcache size >= factor*acceptableSize, we will reject the block into
cache.
was:
In order to avoid blockcache size exceed acceptable size too much, we add one
configuration "hbase.lru.blockcache.hard.capacity.limit.factor" to decide
whether the block could be put into LruBlockCache or not.
If blockcache size >= factor*acceptableSize, we will reject the block into
cache.
> LruBlockCache size should not exceed acceptableSize too many
> ------------------------------------------------------------
>
> Key: HBASE-16287
> URL: https://issues.apache.org/jira/browse/HBASE-16287
> Project: HBase
> Issue Type: Improvement
> Components: BlockCache
> Reporter: Yu Sun
> Assignee: Yu Sun
> Fix For: 2.0.0, 1.3.0, 1.4.0, 1.2.3
>
> Attachments: HBASE-16287-v1.patch, HBASE-16287-v2.patch,
> HBASE-16287-v3.patch, HBASE-16287-v4.patch, HBASE-16287-v5.patch,
> HBASE-16287-v6.patch, HBASE-16287-v7.patch, HBASE-16287-v8.patch,
> HBASE-16287-v9.patch
>
>
> Our regionserver has a configuation as bellow：
> -Xmn4g -Xms32g -Xmx32g -XX:SurvriorRatio=2 -XX:+UseConcMarkSweepGC
> also we only use blockcache,and set hfile.block.cache.size = 0.3 in
> hbase_site.xml,so under this configuration, the lru block cache size will
> be(32g-1g)*0.3=9.3g. but in some scenarios，some of the rs will occur
> continuous FullGC for hours and most importantly, after FullGC most of the
> object in old will not be GCed. so we dump the heap and analyse with MAT and
> we observed a obvious memory leak in LruBlockCache, which occpy about 16g
> memory, then we set set class LruBlockCache log level to TRACE and observed
> this in log:
> {quote}
> 2016-07-22 12:17:58,158 INFO [LruBlockCacheStatsExecutor]
> hfile.LruBlockCache: totalSize=15.29 GB, freeSize=-5.99 GB, max=9.30 GB,
> blockCount=628182, accesses=101799469125, hits=93517800259, hitRatio=91.86%,
> , cachingAccesses=99462650031, cachingHits=93468334621,
> cachingHitsRatio=93.97%, evictions=238199, evicted=4776350518,
> evictedPerRun=20051.93359375{quote}
> we can see blockcache size has exceeded acceptableSize too many, which will
> cause the FullGC more seriously.
> Afterfter some investigations, I found in this function:
> {code:borderStyle=solid}
> public void cacheBlock(BlockCacheKey cacheKey, Cacheable buf, boolean
> inMemory,
> final boolean cacheDataInL1) {
> {code}
> No matter the blockcache size has been used, just put the block into it. but
> if the evict thread is not fast enough, blockcache size will increament
> significantly.
> So here I think we should have a check, for example, if the blockcache size >
> 1.2 * acceptableSize(), just return and dont put into it until the blockcache
> size if under watrmark. if this is reasonable, I can make a small patch for
> this.
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