1: yeah I use JProfiler - top of the charts with a bullet was: org.apache.jackrabbit.util.WeakIdentityCollection$WeakRef (a ha ! that would explain the performance slug when GC has to kick in late in the piece). followed by: org.apache.derby.impl.store.raw.data.StoredRecordHeader and of course a whole lot of byte[]. I am using default everything (which means Derby) and no blobs whatsoever (so all in the database). 2: If I logout, and use fresh everything, it seems to continue fine (ie fast enough pace), but I haven't really pushed it where I wanted to get it (10000 Child nodes). Responding to Alexandru's email (hi alex, nice work on InfoQ if I remember correctly ! I am a fan), it would seem that the Session keeps most in memory, which I can understand. I guess my problem is that I am trying to load up the system to test really basically that it scales to the numbers that I know I need to scale to, but I am having trouble getting the data in - bulk load wise. If I bump up the memory, it certainly seems to hum along better, but if Session is keeping a lot around, then this will have limits - there is no way to "clear" the session ? Perhaps I will explain what I am using JCR for (feel free to smack me down if this is not what JCR and Jackrabbit are ever indended for): I am storing "atomic business rules" (which means each node is a small single business rule). The data on each node is very small. These nodes are stored flat as child nodes under a top level node. To give structure (categorisation) for the users, I have references to these nodes all over the place so people can navigate them all sorts of different ways (as there is no one clear hierarchy at the time the rules are created). JCR gives me most of what I need, but as these rule nodes can number in the thousands (4000 is not uncommon for a reasonably complex business unit), then I am worried that this just can't work. I have seen from past posts that people put nodes under different parents (so there is no great number of child nodes) so that is one option, but my gut feel is that its the WeakIdentityCollection: this well meaning code means that the GC has to due a huge amount of work at the worst possible time (when under stress). I am sure most of the time this is not an issue. Any ideas/tips/gotchas for a newbie? I would really like to be confident that I can scale up enough (its modest) with JCR for this purpose. On 8/31/06, Nicolas wrote: > > 2 more ideas: > > 1/ Did you try using a memory profiler so we can know what is wrong? > > 2/ What happens if you logout after say 100 updates? > > > a+ > Nico > my blog! http://www.deviant-abstraction.net !! > >