I am sorry. I make a mistake. even use RAMDirectory, I can not guarantee they are not swapped out.
On Mon, Jun 11, 2012 at 4:45 PM, Michael Kuhlmann <k...@solarier.de> wrote: > Set the swapiness to 0 to avoid memory pages being swapped to disk too > early. > > http://en.wikipedia.org/wiki/Swappiness > > -Kuli > > Am 11.06.2012 10:38, schrieb Li Li: > >> I have roughly read the codes of RAMDirectory. it use a list of 1024 >> byte arrays and many overheads. >> But as far as I know, using MMapDirectory, I can't prevent the page >> faults. OS will swap less frequent pages out. Even if I allocate >> enough memory for JVM, I can guarantee all the files in the directory >> are in memory. am I understanding right? if it is, then some less >> frequent queries will be slow. How can I let them always in memory? >> >> On Fri, Jun 8, 2012 at 5:53 PM, Lance Norskog<goks...@gmail.com> wrote: >>> >>> Yes, use MMapDirectory. It is faster and uses memory more efficiently >>> than RAMDirectory. This sounds wrong, but it is true. With >>> RAMDirectory, Java has to work harder doing garbage collection. >>> >>> On Fri, Jun 8, 2012 at 1:30 AM, Li Li<fancye...@gmail.com> wrote: >>>> >>>> hi all >>>> I want to use lucene 3.6 providing searching service. my data is >>>> not very large, raw data is less that 1GB and I want to use load all >>>> indexes into memory. also I need save all indexes into disk >>>> persistently. >>>> I originally want to use RAMDirectory. But when I read its javadoc. >>>> >>>> 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. >>>> >>>> should I use MMapDirectory? it seems another contrib instantiated. >>>> anyone test it with RAMDirectory? >>> >>> >>> >>> >>> -- >>> Lance Norskog >>> goks...@gmail.com > >
