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From "Robert Muir (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-8005) Avoid Class.getSimpleName in UsageTrackingQueryCachingPolicy
Date Mon, 23 Oct 2017 20:42:00 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-8005?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16215797#comment-16215797
] 

Robert Muir commented on LUCENE-8005:
-------------------------------------

{quote}
So a sizable improvement but not as fast as an instanceof check.
{quote}

But this is not the bottleneck for lucene's processing so we can't make decisions that way.
Otherwise we optimize the wrong stuff. i wish it was the bottleneck, that 10 million queries
could run in 20ms versus 900ms. But a ~ 100 ns cost to check if a query is cached seems reasonable
to me. And the current speed of ~ 1 microsecond per query seems also just fine. 

I am more concerned that we don't introduce bad apis and complex abstractions. In this case
I'm sorry, i dont see a performance justification for that.

> Avoid Class.getSimpleName in UsageTrackingQueryCachingPolicy
> ------------------------------------------------------------
>
>                 Key: LUCENE-8005
>                 URL: https://issues.apache.org/jira/browse/LUCENE-8005
>             Project: Lucene - Core
>          Issue Type: Improvement
>            Reporter: Scott Somerville
>         Attachments: LUCENE-8005.patch, LUCENE-8005.patch
>
>
> By profiling an Elasticsearch cluster, I found the private method UsageTrackingQueryCachingPolicy.isPointQuery
to be quite expensive due to the clazz.getSimpleName() call.
> Here is an excerpt from hot_threads:
> {noformat}
> java.lang.Class.getEnclosingMethod0(Native Method)
>        java.lang.Class.getEnclosingMethodInfo(Class.java:1072)
>        java.lang.Class.getEnclosingClass(Class.java:1272)
>        java.lang.Class.getSimpleBinaryName(Class.java:1443)
>        java.lang.Class.getSimpleName(Class.java:1309)
>        org.apache.lucene.search.UsageTrackingQueryCachingPolicy.isPointQuery(UsageTrackingQueryCachingPolicy.java:39)
>        org.apache.lucene.search.UsageTrackingQueryCachingPolicy.isCostly(UsageTrackingQueryCachingPolicy.java:54)
>        org.apache.lucene.search.UsageTrackingQueryCachingPolicy.minFrequencyToCache(UsageTrackingQueryCachingPolicy.java:121)
>        org.apache.lucene.search.UsageTrackingQueryCachingPolicy.shouldCache(UsageTrackingQueryCachingPolicy.java:179)
>        org.elasticsearch.index.shard.ElasticsearchQueryCachingPolicy.shouldCache(ElasticsearchQueryCachingPolicy.java:53)
>        org.apache.lucene.search.LRUQueryCache$CachingWrapperWeight.bulkScorer(LRUQueryCache.java:806)
>        org.elasticsearch.indices.IndicesQueryCache$CachingWeightWrapper.bulkScorer(IndicesQueryCache.java:168)
>        org.apache.lucene.search.IndexSearcher.search(IndexSearcher.java:665)
>        org.apache.lucene.search.IndexSearcher.search(IndexSearcher.java:472)
>        org.elasticsearch.search.query.QueryPhase.execute(QueryPhase.java:388)
>        org.elasticsearch.search.query.QueryPhase.execute(QueryPhase.java:108)
> {noformat}



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