Otherwise, I just found this : http://code.google.com/p/concurrentlinkedhashmap/
AL 2.0, so we may use it. Worth a try, IMO. Le 9/2/13 7:11 PM, Mohit Srivastava a écrit : > I think we can use EhCache for now. Also modify it for our purposes. > > > On 2 September 2013 14:32, Emmanuel Lécharny <[email protected]> wrote: > >> Hi guys, >> >> I have done some tests a week ago on Mavibot partition. It appears that >> we have a serious performance issue as soon as the JVM memory is >> completly eaten, when adding some entries. What happens is that we start >> to discard some pages as they are hold by WeakReferences, and the GC has >> to do quite a expensive processing to get back some free memory. This >> slows down the add operation so much (by at least a factor 10) that it's >> not possible to keep going with WeakReferences (or SoftReferences). >> >> At this point, the best solution would be to use a cache to replace this >> mechanism. >> >> There are different things we can cache : >> o PageIo : it's useless, as we still have to deserialize them afterward >> o Nodes and Leaves : They contain references to other Nodes or Leaves, >> and for Leaves, reference to data. Holding the upper Nodes would save us >> a lot of time >> o Data : the ultimate objects to cache : having the object in cache >> spares us the time it takes to searcj it in a Btree >> >> A few other things to consider : >> o we need a versionned cache : all the elements may be versionned. >> o each BTree may be cached, with different configuation (some BTree may >> be used rarely, other may be heavily used, requiring a more aggressive >> cache configuration) >> o the Cache must not use locks, but CAS (Compare-And-Swap) for better >> performance >> >> At this point, I suggest using EhCache as a first approach, in order to >> leverage the cache we already use in the server, but we may want to >> design our own LRU cache (something that should not be too complex to >> implement). >> >> Thoughts ? >> >> -- >> Regards, >> Cordialement, >> Emmanuel Lécharny >> www.iktek.com >> >> -- Regards, Cordialement, Emmanuel Lécharny www.iktek.com
