Hi, >From: Vadim Gritsenko [mailto:[EMAIL PROTECTED]] > >> From: Gerhard Froehlich [mailto:[EMAIL PROTECTED]] >> >> Hi, >> >> >-----Original Message----- >> >From: Britton, Colin [mailto:[EMAIL PROTECTED]] >> >Sent: Monday, January 28, 2002 5:59 PM >> >To: [EMAIL PROTECTED] >> >Subject: RE: cvs commit: MRUMemoryStore.java >FilesystemQueueObject.java >> > >> > >> >For our application I want to not only cache from memory, but also >store >> >the objects on the fileSystem (as the cost of generation in our app >can >> >be high). With the change so that items are only written to the file >> >system when the number of memory objects reaches max and this.free() >is >> >called it seems that we loose this capability unless we set the >memory >> >objects to a small number (which defeats the objective of the cache >and >> >having lots of memory). One of the benefits of the old way was that >if >> >the VM unexpectedly quits we had the file system cache for all the >items >> >that were in memory. Also all memory objects are lost after shutdown, >> >maybe it would also be also a good idea to write the memory objects >to >> >disk on a formal shutdown (this was not needed with the old method) >if >> >the queue method is not returned. >> >> You can't imagine how much thoughts I wasted for that issue. I will >> explain you them (again): >> >> a) The old way stored every object twice. First in Memory, Second on >the >> Filesystem. That was a very _expensive_ operation. We needed an extra >> thread which did all that serialization and he eated performance. >> The only real advantage was to have the objects persistent after a JVM >> restart. Therefor I never had a good feeling about that. This are too >> little advantages. >> >> And besides, how often crashes the JVM. Every day, weekly, monthly. >How long >> does it take till the old caching status is reached? The first user >gets >> a slow page. The next a quick one. >> >> I wanna have a clean implementation. This other issues are parts of >the >> adaptive >> caching or something else I say. It must be simple! >> >> b) The new way behaves more like a normal OS cache. First everything >is >> handeld >> in memory. If this is running, old ones are swapped out to make room >for >> others. > >New store implementation - does it swaps to file system when removing >items from the stores?
Yep it does. When the free() method is called, the oldest object is swapped to Filsystem. That's the main difference here. >> At least I see no way how to handle a formal shutdown. Did would be >the >> best. Then we could catch this event and save the memory store down to >> the Filesystem. > >No problems with this. Implement Disposable interface. Does it catch "ctlr-c" or "kill" under Unix, when I shutdown for i.e. Tomcat >Vadim Gerhard ------------------------------------------- Beer is God's way of showing us he loves us and wants us to be happy... ------------------------------------------- --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, email: [EMAIL PROTECTED]
