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https://issues.apache.org/jira/browse/HBASE-25698?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17337786#comment-17337786
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Anoop Sam John commented on HBASE-25698:
----------------------------------------
This is external Block Cache usage. So Bucket Cache is not coming into pic
there. The diff is this
In case when Bucket Cache is in use, there is no more L1 , L2 funda now. The
data blocks go to Bucket Cache always and Index, bloom etc goes to on heap LRU
cache. There is no victim stuff here at all. So given a block type we know
where to keep it and read it from
In case of external block cache usage (As of now only Memcached based cache),
its proper L1 L2 stuff. There will be on heap LRU cache as L1. The caching
always try to put blocks (whatever be the type) into L1. L2 (external cache)
is configured as victim handler and evictions from L1 will move the blocks to
L2. So when getBlock() comes, we check with both L1 and L2.
Do we have a section for external cache in ref guide, we can write this info
there if not yet.
The 1st para can be at Bucket Cache section. Will come back to that.
> Persistent IllegalReferenceCountException at scanner open when using
> TinyLfuBlockCache
> --------------------------------------------------------------------------------------
>
> Key: HBASE-25698
> URL: https://issues.apache.org/jira/browse/HBASE-25698
> Project: HBase
> Issue Type: Bug
> Components: HFile, Scanners
> Affects Versions: 2.4.2
> Reporter: Andrew Kyle Purtell
> Assignee: Viraj Jasani
> Priority: Major
> Fix For: 3.0.0-alpha-1, 2.5.0, 2.4.3
>
>
> Persistent scanner open failure with offheap read path enabled.
> Not sure how it happened. Test scenario was HBase 1 cluster replicating to
> HBase 2 cluster. ITBLL as data generator at source, calm policy only. Scanner
> open errors on sink HBase 2 cluster later during ITBLL verify phase. Sink
> schema settings bloom=ROW encoding=FAST_DIFF compression=NONE.
> {noformat}
> Caused by:
> org.apache.hbase.thirdparty.io.netty.util.IllegalReferenceCountException:
> refCnt: 0, decrement: 1
> at
> org.apache.hbase.thirdparty.io.netty.util.internal.ReferenceCountUpdater.toLiveRealRefCnt(ReferenceCountUpdater.java:74)
> at
> org.apache.hbase.thirdparty.io.netty.util.internal.ReferenceCountUpdater.release(ReferenceCountUpdater.java:138)
> at
> org.apache.hbase.thirdparty.io.netty.util.AbstractReferenceCounted.release(AbstractReferenceCounted.java:76)
> at org.apache.hadoop.hbase.nio.ByteBuff.release(ByteBuff.java:79)
> at
> org.apache.hadoop.hbase.io.hfile.HFileBlock.release(HFileBlock.java:429)
> at
> org.apache.hadoop.hbase.io.hfile.CompoundBloomFilter.contains(CompoundBloomFilter.java:109)
> at
> org.apache.hadoop.hbase.regionserver.StoreFileReader.checkGeneralBloomFilter(StoreFileReader.java:433)
> at
> org.apache.hadoop.hbase.regionserver.StoreFileReader.passesGeneralRowBloomFilter(StoreFileReader.java:322)
> at
> org.apache.hadoop.hbase.regionserver.StoreFileReader.passesBloomFilter(StoreFileReader.java:251)
> at
> org.apache.hadoop.hbase.regionserver.StoreFileScanner.shouldUseScanner(StoreFileScanner.java:491)
> at
> org.apache.hadoop.hbase.regionserver.StoreScanner.selectScannersFrom(StoreScanner.java:471)
> at
> org.apache.hadoop.hbase.regionserver.StoreScanner.<init>(StoreScanner.java:249)
> at
> org.apache.hadoop.hbase.regionserver.HStore.createScanner(HStore.java:2177)
> at
> org.apache.hadoop.hbase.regionserver.HStore.getScanner(HStore.java:2168)
> at
> org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.initializeScanners(HRegion.java:7172)
> {noformat}
> Bloom filter type on all files here is ROW, block encoding is FAST_DIFF:
> {noformat}
> hbase:017:0> describe "IntegrationTestBigLinkedList"
> Table IntegrationTestBigLinkedList is ENABLED
>
> IntegrationTestBigLinkedList
>
> COLUMN FAMILIES DESCRIPTION
>
> {NAME => 'big', BLOOMFILTER => 'ROW', IN_MEMORY => 'false', VERSIONS => '1',
> KEEP_DELETED_CELLS => 'FALSE', DATA_BLOCK_ENCODING => 'FAST_DIF
> F', COMPRESSION => 'NONE', TTL => 'FOREVER', MIN_VERSIONS => '0', BLOCKCACHE
> => 'true', BLOCKSIZE => '65536', REPLICATION_SCOPE => '1'}
> {NAME => 'meta', BLOOMFILTER => 'ROW', IN_MEMORY => 'false', VERSIONS => '1',
> KEEP_DELETED_CELLS => 'FALSE', DATA_BLOCK_ENCODING => 'FAST_DI
> FF', COMPRESSION => 'NONE', TTL => 'FOREVER', MIN_VERSIONS => '0', BLOCKCACHE
> => 'true', BLOCKSIZE => '65536', REPLICATION_SCOPE => '1'}
> {NAME => 'tiny', BLOOMFILTER => 'ROW', IN_MEMORY => 'false', VERSIONS => '1',
> KEEP_DELETED_CELLS => 'FALSE', DATA_BLOCK_ENCODING => 'FAST_DI
> FF', COMPRESSION => 'NONE', TTL => 'FOREVER', MIN_VERSIONS => '0', BLOCKCACHE
> => 'true', BLOCKSIZE => '65536', REPLICATION_SCOPE => '1'}
> {noformat}
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