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https://issues.apache.org/jira/browse/HBASE-15162?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15115541#comment-15115541
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stack commented on HBASE-15162:
-------------------------------
Small stuff [~carp84]
{code}
338 String BLOCK_CACHE_EXPRESS_META_HIT_PERCENT =
"blockCacheExpressMetaHitPercent";
339 String BLOCK_CACHE_EXPRESS_META_HIT_PERCENT_DESC =
340 "The percent of the time that requests with the cache turned on
hit the meta cache.";
341 String BLOCK_CACHE_EXPRESS_DATA_HIT_PERCENT =
"blockCacheExpressDataHitPercent";
342 String BLOCK_CACHE_EXPRESS_DATA_HIT_PERCENT_DESC =
343 "The percent of the time that requests with the cache turned on
hit the data cache.";
{code}
What does the 'express' mean in the above? The name of the method seems like a
better name for the metric: getBlockCacheMetaHitCachingPercent... i.e.
BLOCK_CACHE_META_HIT_PERCENTAGE.
It is not possible to turn off block cache for meta blocks so the description
can drop 'with the cache turned on'.
If L2 is enabled -- i.e. bucket cache -- then all data blocks go into L2 and L1
carries meta blocks only. These metrics will still make 'sense' when
bucketcache is on? It seems so. Just asking....
Otherwise, patch looks great.
> Add separate metrics for meta/data block hit ratio in cache
> -----------------------------------------------------------
>
> Key: HBASE-15162
> URL: https://issues.apache.org/jira/browse/HBASE-15162
> Project: HBase
> Issue Type: Sub-task
> Reporter: Yu Li
> Assignee: Yu Li
> Attachments: HBASE-15162.patch, HBASE-15162_v2.patch
>
>
> Currently we already have a metrics in name of
> {{blockCacheExpressHitPercent}} to indicate the cache hit ratio. However,
> since meta block is small and often cached in memory with a high hit ratio,
> this "mixed" metrics could not show the real data block hit ratio which is
> more concerned.
> We propose to add two new metrics to show meta and data block cache hit ratio
> separately, while reserving the old metrics for backward compatibility.
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