[jira] [Created] (OAK-863) Enable stats for various caches used in Oak by default

["Chetan Mehrotra (JIRA)" <ji...@apache.org>]

Chetan Mehrotra created OAK-863:
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             Summary: Enable stats for various caches used in Oak by default
                 Key: OAK-863
                 URL: https://issues.apache.org/jira/browse/OAK-863
             Project: Jackrabbit Oak
          Issue Type: Improvement
            Reporter: Chetan Mehrotra
            Assignee: Chetan Mehrotra
            Priority: Minor


To get a better picture around the usage of cache it would be helpful to enable the [statistics|http://code.google.com/p/guava-libraries/wiki/CachesExplained#Statistics] for various caches used in Oak

{code:java}
nodeCache = CacheBuilder.newBuilder()
                        .weigher(...)
                        .maximumWeight(...)
                        .recordStats()
                        .build();
{code}

Once enabled it allows to get stats like below
{noformat}
CacheStats{hitCount=763322, missCount=51333, loadSuccessCount=0, loadExceptionCount=0, totalLoadTime=0, evictionCount=3496}
{noformat}

As stats collection adds a very minor overhead we can look into making this setting configurable. 

Untill we expose the stats via JMX one can extract the value in Sling env via approach mentioned in [this gist|https://gist.github.com/chetanmeh/5748650]

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