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  1. HBase
  2. HBASE-8315

Documentation should have more information of LRU Stats

    Details

    • Type: Improvement
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 0.95.0
    • Fix Version/s: 0.99.0
    • Component/s: documentation
    • Labels:

      Description

      Unfortunately, there's no documentation to explain the meaning of each LRU Stats in the regionserver logs. So this is for creating a new paragraph regarding this. My current idea is below, but it's a little bit difficult to explain the difference between 'cachingAccesses' and 'accesses' from an administrator or a user views.
      Could you guys help to improve the content?

      total: The current memory size of the cache in use.
      free: The total free memory currently available to store more cache entries.
      max: Maximum allowed memory size of the cache.
      blocks: Caches store blocks of data; this number is the current # of blocks stored, which use up the "total" memory space.
      accesses: The total number of times the cache was accessed, regardless of result.
      hits: The total number of times the cache was accessed and the result was a successful hit (presence of looked up element in cache is a hit).
      hitRatio: The current percentage for "hits / accesses".
      
      ====
      Unclear:
      cachingAccesses: cachingHits + The number of getBlock requests that were cache misses, but only from requests that were set to use the block cache.
      cachingHits: The number of getBlock requests that were cache hits, but only from requests that were set to use the block cache. This is because all reads
      =====
      
      cachingHitsRatio: The current percentage for "cachintHits / cachingAccesses"
      evictions: The total number of times an eviction has occurred (based on the use of the LRU algorithm)
      evicted: The total number of blocks that have been evicted (based on the use of the LRU algorithm)
      evictedPerRun: The total number of blocks that have been evicted overall / The number of times an eviction has occurred overall
      

      And also, where should we add this paragraph in the documentation?

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            • Assignee:
              misty Misty Stanley-Jones
              Reporter:
              daisuke.kobayashi Daisuke Kobayashi
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              • Created:
                Updated:
                Resolved: