[ 
https://issues.apache.org/jira/browse/LUCENE-1609?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12701973#action_12701973
 ] 

Uwe Schindler commented on LUCENE-1609:
---------------------------------------

Are you sure, this works correct? If the indexState is changed in the 
synchronized block, another thread not synchronizing on the lock may still see 
the old indexState. At least, the indexState must be volatile, but this only 
works correct with Java 1.5 (and Lucene only needs Java 1.4 as requirement).

> Eliminate synchronization contention on initial index reading in 
> TermInfosReader ensureIndexIsRead 
> ---------------------------------------------------------------------------------------------------
>
>                 Key: LUCENE-1609
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1609
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Index
>    Affects Versions: 2.9
>         Environment: Solr 
> Tomcat 5.5
> Ubuntu 2.6.20-17-generic
> Intel(R) Pentium(R) 4 CPU 2.80GHz, 2Gb RAM
>            Reporter: Dan Rosher
>         Attachments: LUCENE-1609.patch
>
>
> synchronized method ensureIndexIsRead in TermInfosReader causes contention 
> under heavy load
> Simple to reproduce: e.g. Under Solr, with all caches turned off, do a simple 
> range search e.g. id:[0 TO 999999] on even a small index (in my case 28K 
> docs) and under a load/stress test application, and later, examining the 
> Thread dump (kill -3) , many threads are blocked on 'waiting for monitor 
> entry' to this method.
> Rather than using Double-Checked Locking which is known to have issues, this 
> implementation uses a state pattern, where only one thread can move the 
> object from IndexNotRead state to IndexRead, and in doing so alters the 
> objects behavior, i.e. once the index is loaded, the index nolonger needs a 
> synchronized method. 
> In my particular test, this uncreased throughput at least 30 times.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


---------------------------------------------------------------------
To unsubscribe, e-mail: java-dev-unsubscr...@lucene.apache.org
For additional commands, e-mail: java-dev-h...@lucene.apache.org

Reply via email to