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Mike Klaas commented on SOLR-665: --------------------------------- [quote]We may simply use java.util.concurrent.locks instead of heavy synchronized... we may also use Executor framework instead of single-thread faceting... We may even base SOLR on Apache MINA project.[/quote] Simply replacing synchronized with java.util.concurrent.locks doesn't increase performance. There needs to be a specific strategy for employing these locks in a way that makes sense. For instance, one idea would be to create a read/write lock with the put()'s covered by write and get()'s covered by read. This would allow multiple parallel reads and will be thread-safe. Another is to create something like ConcurrentLinkedHashMap. These strategies should be tested before trying to create a lock-free get() version, which if even possible, would rely deeply on the implementation (such a structure would have to be created from scratch, I believe). I'd expect anyone that is able to create such a thing be familiar enough wiht memory barriers and such issues to be able to deeply explain the problems with double-checked locking off the top of their head (and immediately see such problems in other code) > FIFO Cache (Unsynchronized): 9x times performance boost > ------------------------------------------------------- > > Key: SOLR-665 > URL: https://issues.apache.org/jira/browse/SOLR-665 > Project: Solr > Issue Type: Improvement > Affects Versions: 1.3 > Environment: JRockit R27 (Java 6) > Reporter: Fuad Efendi > Attachments: FIFOCache.java > > Original Estimate: 672h > Remaining Estimate: 672h > > Attached is modified version of LRUCache where > 1. map = new LinkedHashMap(initialSize, 0.75f, false) - so that > "reordering"/true (performance bottleneck of LRU) is replaced to > "insertion-order"/false (so that it became FIFO) > 2. Almost all (absolutely unneccessary) synchronized statements commented out > See discussion at > http://www.nabble.com/LRUCache---synchronized%21--td16439831.html > Performance metrics (taken from SOLR Admin): > LRU > Requests: 7638 > Average Time-Per-Request: 15300 > Average Request-per-Second: 0.06 > FIFO: > Requests: 3355 > Average Time-Per-Request: 1610 > Average Request-per-Second: 0.11 > Performance increased 9 times which roughly corresponds to a number of CPU in > a system, http://www.tokenizer.org/ (Shopping Search Engine at Tokenizer.org) > Current number of documents: 7494689 > name: filterCache > class: org.apache.solr.search.LRUCache > version: 1.0 > description: LRU Cache(maxSize=10000000, initialSize=1000) > stats: lookups : 15966954582 > hits : 16391851546 > hitratio : 0.102 > inserts : 4246120 > evictions : 0 > size : 2668705 > cumulative_lookups : 16415839763 > cumulative_hits : 16411608101 > cumulative_hitratio : 0.99 > cumulative_inserts : 4246246 > cumulative_evictions : 0 > Thanks -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.