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https://issues.apache.org/jira/browse/HBASE-26083?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17379222#comment-17379222
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Anoop Sam John commented on HBASE-26083:
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Ah.. !! Good catch
> In branch-2 & branch-1 L1 miss metric is always 0 when using
> CombinedBlockCache
> -------------------------------------------------------------------------------
>
> Key: HBASE-26083
> URL: https://issues.apache.org/jira/browse/HBASE-26083
> Project: HBase
> Issue Type: Bug
> Affects Versions: 1.7.0, 2.4.4
> Reporter: Yutong Xiao
> Assignee: Yutong Xiao
> Priority: Major
>
> In CombinedBlockCache getBlock method
> {code:java}
> public Cacheable getBlock(BlockCacheKey cacheKey, boolean caching,
> boolean repeat, boolean updateCacheMetrics) {
> // TODO: is there a hole here, or just awkwardness since in the lruCache
> getBlock
> // we end up calling l2Cache.getBlock.
> // We are not in a position to exactly look at LRU cache or BC as
> BlockType may not be getting
> // passed always.
> return l1Cache.containsBlock(cacheKey)?
> l1Cache.getBlock(cacheKey, caching, repeat, updateCacheMetrics):
> l2Cache.getBlock(cacheKey, caching, repeat, updateCacheMetrics);
> }
> {code}
> If L1 does not contains cacheKey, it will never check it in L1, so that L1
> miss metrics is always 0.
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