Makes sense. Thanks -----Original Message----- From: Toke Eskildsen [mailto:t...@statsbiblioteket.dk] Sent: Tuesday, June 07, 2011 4:28 PM To: java-user@lucene.apache.org Subject: Re: RAMDirectory doesn't win over FSDirectory all the time, why?
On Mon, 2011-06-06 at 15:29 +0200, zhoucheng2008 wrote: > I read the lucene in action book and just tested the > FSversusRAMDirectoryTest.java with the following uncommented: > [...]Here is the output: > > RAMDirectory Time: 805 ms > > FSDirectory Time : 728 ms This is the code, right? http://java.codefetch.com/example/in/LuceneInAction/src/lia/indexing/FSversusRAMDirectoryTest.java The test is problematic as the same two tests run sequentially. If you change long ramTiming = timeIndexWriter(ramDir); long fsTiming = timeIndexWriter(fsDir); to long fsTiming = timeIndexWriter(fsDir); long ramTiming = timeIndexWriter(ramDir); my guess is that RAMDirectory will be faster. For a better comparison, perform each test in separate runs (make a test class just for RAMDirectory and one just for FSDirectory, then run them one at a time, each in its own JVM). One big problem when comparing RAMDirectory to file-access is caching. What you measure with a test might not be what you see in production, as the production index might be large compared to RAM available for file caching. --------------------------------------------------------------------- To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org For additional commands, e-mail: java-user-h...@lucene.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org For additional commands, e-mail: java-user-h...@lucene.apache.org
