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Posted to dev@lucene.apache.org by "Yonik Seeley (JIRA)" <ji...@apache.org> on 2013/03/19 16:09:15 UTC
[jira] [Commented] (SOLR-4589) 4.x + enableLazyFieldLoading + large
multivalued fields + varying fl = pathological CPU load & response time
[ https://issues.apache.org/jira/browse/SOLR-4589?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13606388#comment-13606388 ]
Yonik Seeley commented on SOLR-4589:
------------------------------------
Still trying to wrap my head around how all this works... particularly with synchronization and why the old implementation, or the patch, are thread safe.
I'm not sure we should be using weak references though. They could cause problems at the rate they could be generated.
> 4.x + enableLazyFieldLoading + large multivalued fields + varying fl = pathological CPU load & response time
> ------------------------------------------------------------------------------------------------------------
>
> Key: SOLR-4589
> URL: https://issues.apache.org/jira/browse/SOLR-4589
> Project: Solr
> Issue Type: Bug
> Affects Versions: 4.0, 4.1, 4.2
> Reporter: Hoss Man
> Assignee: Hoss Man
> Fix For: 4.2.1
>
> Attachments: SOLR-4589.patch, SOLR-4589.patch, test-just-queries.out__4.0.0_mmap_lazy_using36index.txt, test-just-queries.sh, test.out__3.6.1_mmap_lazy.txt, test.out__3.6.1_mmap_nolazy.txt, test.out__3.6.1_nio_lazy.txt, test.out__3.6.1_nio_nolazy.txt, test.out__4.0.0_mmap_lazy.txt, test.out__4.0.0_mmap_nolazy.txt, test.out__4.0.0_nio_lazy.txt, test.out__4.0.0_nio_nolazy.txt, test.out__4.2.0_mmap_lazy.txt, test.out__4.2.0_mmap_nolazy.txt, test.out__4.2.0_nio_lazy.txt, test.out__4.2.0_nio_nolazy.txt, test.sh
>
>
> Following up on a [user report of exterme CPU usage in 4.1|http://mail-archives.apache.org/mod_mbox/lucene-solr-user/201302.mbox/%3C1362019882934-4043543.post@n3.nabble.com%3E], I've discovered that the following combination of factors can result in extreme CPU usage and excessively HTTP response times...
> * Solr 4.x (tested 3.6.1, 4.0.0, and 4.2.0)
> * enableLazyFieldLoading == true (included in example solrconfig.xml)
> * documents with a large number of values in multivalued fields (eg: tested ~10-15K values)
> * multiple requests returning the same doc with different "fl" lists
> I haven't dug into the route cause yet, but the essential observations is: if lazyloading is used in 4.x, then once a document has been fetched with an initial fl list X, subsequent requests for that document using a differnet fl list Y can be many orders of magnitute slower (while pegging the CPU) -- even if those same requests using fl Y uncached (or w/o lazy laoding) would be extremely fast.
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