Hi ho peoples.We have an application that is internationalized, and stores data from many languages (each project has it's own index, mostly aligned with a single language, maybe 2).
Anyway, I've noticed during some thread dumps diagnosing some performance issues, that there appears to be a _potential_ synchronization bottleneck using Locale-based sorting of Strings. I don't think this problem is the root cause of our performance problem, but I thought I'd mention it here. Here's the stack dump of a thread waiting:
"http-1001-Processor245" daemon prio=1 tid=0x31434da0 nid=0x3744 waiting for monitor entry [0x2cd44000..0x2cd45f30]
at java.text.RuleBasedCollator.compare(RuleBasedCollator.java)
- waiting to lock <0x6b1e8c68> (a java.text.RuleBasedCollator)
at org.apache.lucene.search.FieldSortedHitQueue$4.compare
(FieldSortedHitQueue.java:320)
at org.apache.lucene.search.FieldSortedHitQueue.lessThan
(FieldSortedHitQueue.java:114)
at org.apache.lucene.util.PriorityQueue.upHeap
(PriorityQueue.java:120)
at org.apache.lucene.util.PriorityQueue.put
(PriorityQueue.java:47)
at org.apache.lucene.util.PriorityQueue.insert
(PriorityQueue.java:58)
at org.apache.lucene.search.FieldSortedHitQueue.insert
(FieldSortedHitQueue.java:90)
at org.apache.lucene.search.FieldSortedHitQueue.insert
(FieldSortedHitQueue.java:97)
at org.apache.lucene.search.TopFieldDocCollector.collect
(TopFieldDocCollector.java:47)
at org.apache.lucene.search.BooleanScorer2.score
(BooleanScorer2.java:291)
at org.apache.lucene.search.IndexSearcher.search
(IndexSearcher.java:132)
at org.apache.lucene.search.IndexSearcher.search
(IndexSearcher.java:110)
at com.aconex.index.search.FastLocaleSortIndexSearcher.search
(FastLocaleSortIndexSearcher.java:90)
.....In our case we had 12 threads waiting like this, while one thread had the lock on the RuleBasedCollator. Turns out RuleBasedCollator's.compare(...) method is synchronized. I wonder if a ThreadLocal based collator would be better here... ? There doesn't appear to be a reason for other threads searching the same index to wait on this sort. Be just as easy to use their own. (Is RuleBasedCollator a "heavy" object memory wise? Wouldn't have thought so, per thread)
Thoughts? Paul Smith Engineering Manager Aconex The easy way to save time and money on your project 696 Bourke Street, Melbourne, VIC 3000, Australia Tel: +61 3 9240 0200 Fax: +61 3 9240 0299 Email: [EMAIL PROTECTED] www.aconex.comThis email and any attachments are intended solely for the addressee. The contents may be privileged, confidential and/or subject to copyright or other applicable law. No confidentiality or privilege is lost by an erroneous transmission. If you have received this e-mail in error, please let us know by reply e-mail and delete or destroy this mail and all copies. If you are not the intended recipient of this message you must not disseminate, copy or take any action in reliance on it. The sender takes no responsibility for the effect of this message upon the recipient's computer system.
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