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From "Bin Shi (JIRA)" <j...@apache.org>
Subject [jira] [Created] (PHOENIX-5069) Use asynchronous refresh to provide non-blocking Phoenix Stats Client Cache
Date Thu, 13 Dec 2018 19:20:00 GMT
Bin Shi created PHOENIX-5069:
--------------------------------

             Summary: Use asynchronous refresh to provide non-blocking Phoenix Stats Client
Cache
                 Key: PHOENIX-5069
                 URL: https://issues.apache.org/jira/browse/PHOENIX-5069
             Project: Phoenix
          Issue Type: Improvement
            Reporter: Bin Shi
         Attachments: image-2018-12-13-11-16-16-884.png

Below is the high level picture of Phoenix Stats Cache which is based on Google Guava cache.
 !OmCWFETQAAAABJRU5ErkJggg==! The current Phoenix Stats Cache uses TTL based eviction policy.
A cached entry will expire after a given amount of time (900s by default) passed since the
entry's been created. This will lead to cache miss when Compiler/Optimizer fetches stats from
cache at the next time. As you can see from the above graph, fetching stats from the cache
is a blocking operation — when there is cache miss, it has a round trip over the wire to
scan the SYSTEM.STATS Table and to get the latest stats info, rebuild the cache and finally
return the stats to the Compiler/Optimizer. Whenever there is a cache miss, this blocking
call causes significant performance penalty and see periodic spikes.

This Jira suggests to use asynchronous refresh mechanism[link title|http://example.com][link
title|http://example.com] to fix this and provide a non-blocking cache.



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