Can I control the size of ram given to either MMapDirectory or ByteBufferDirectory?
On Mon, Jun 4, 2012 at 11:42 PM, Uwe Schindler <u...@thetaphi.de> wrote: > Hi, > > If you are using MMapDirectory or this ByteBufferDirectory (which is > similar to the first) the used RAM is outside JVM heap, it is in the FS > cache of the OS kernel. Giving too much memory to the JVM penalizes the OS > cache, so give only as much as the App needs. Lucene and the OS kernel will > then utilize the remaining memory for caching. > > Please read docs of MMapDirectory and inform yourself about mmap in e.g. > Wikipedia. > > Uwe > -- > Uwe Schindler > H.-H.-Meier-Allee 63, 28213 Bremen > http://www.thetaphi.de > > > > Cheng <zhoucheng2...@gmail.com> schrieb: > > Please shed more insight into the difference between JVM heap size and the > memory size used by Lucene. > > What I am getting at is that no matter however much ram I give my apps, > Lucene can't utilize it. Is that right? > > What about the ByteBufferDirectory? Can this specific directory utilize the > 2GB memory I grant to the app? > > On Mon, Jun 4, 2012 at 10:58 PM, Jason Rutherglen < > jason.rutherg...@gmail.com> wrote: > > > If you want the index to be stored completely in RAM, there is the > > ByteBuffer directory [1]. Though I do not see the point in putting an > > index in RAM, it will be cached in RAM regardless in the OS system IO > > cache. > > > > 1. > > > https://github.com/elasticsearch/elasticsearch/blob/master/src/main/java/org/apache/lucene/store/bytebuffer/ByteBufferDirectory.java > > > > On Mon, Jun 4, 2012 at 10:55 AM, Cheng <zhoucheng2...@gmail.com> wrote: > > > My indexes are 500MB+. So it seems like that RAMDirectory is not good > for > > > that big a size. > > > > > > My challenge, on the other side, is that I need to update the indexes > > very > > > frequently. So, do you think MMapDirectory is the solution? > > > > > > Thanks. > > > > > > On Mon, Jun 4, 2012 at 10:30 PM, Jack Krupansky < > j...@basetechnology.com > > >wrote: > > > > > >> From the javadoc for RAMDirectory: > > >> > > >> "Warning: This class is not intended to work with huge indexes. > > Everything > > >> beyond several hundred megabytes will waste resources (GC cycles), > > because > > >> it uses an internal buffer size of 1024 bytes, producing millions of > > >> byte[1024] arrays. This class is optimized for small memory-resident > > >> indexes. It also has bad concurrency on multithreaded environments. > > >> > > >> It is recommended to materialize large indexes on disk and use > > >> MMapDirectory, which is a high-performance directory implementation > > working > > >> directly on the file system cache of the operating system, so copying > > data > > >> to Java heap space is not useful." > > >> > > >> -- Jack Krupansky > > >> > > >> -----Original Message----- From: Cheng > > >> Sent: Monday, June 04, 2012 10:08 AM > > >> To: java-user@lucene.apache.org > > >> Subject: RAMDirectory unexpectedly slows > > >> > > >> > > >> Hi, > > >> > > >> My apps need to read from and write to some big indexes frequently. > So I > > >> use RAMDirectory instead of FSDirectory, and give JVM about 2GB memory > > >> size. > > >> > > >> I notice that the speed of reading and writing unexpectedly slows as > the > > >> size of the indexes increases. Since the usage of RAM is less than > 20%, > > I > > >> think by default the RAMDirectory doesn't take advantage of the > memory I > > >> assigned to JVM. > > >> > > >> What are the steps to improve the reading and writing speed of > > >> RAMDirectory? > > >> > > >> Thanks! > > >> Jeff > > >> > > >> > >_____________________________________________ > **_____________________________________________ > **--------- > > >> To unsubscribe, e-mail: java-user-unsubscribe@lucene.**apache.org< > > java-user-unsubscr...@lucene.apache.org> > > >> For additional commands, e-mail: java-user-help@lucene.apache.**org< > > 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 > > > > > >
