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From "Michael Neale" <michael.ne...@gmail.com>
Subject Re: OutOfMemory - adding lots of nodes in one session
Date Mon, 04 Sep 2006 12:41:21 GMT
Hi Stefan.

Node types attached, and the example code that rips through it and saves
stuff. Let me know if there is anything obvious I am doing wrong !


Any one interested can download the loop code and node types from this zip:
http://www.users.on.net/~michaelneale/work/jackrabbit_perf.zip

On 9/4/06, Stefan Guggisberg <stefan.guggisberg@gmail.com> wrote:
>
> hi michael,
>
> On 9/4/06, Michael Neale <michael.neale@gmail.com> wrote:
> > hi Stefan.
> >
> > Yes I was able to make it rip through saving lots of simple nodes like
> that
> > no problem.
> > When I add more properties, it degrades a fair bit (probably not
> surprising
> > if I guess at how the data is being stored for each property).
> >
> > Interestingly, when I use my own specific node type it slows down quite
> a
> > lot (and memory consumption goes up) then with nt:unstructured, yet with
> all
> > other properties being set in the same way. I had to bump up the memory
> > quite a lot to avoid OutOfMemoryException's.
>
> that's indeed very interesting and comes as a surprise. would you mind
> sharing
> with us your node type definitions and some sample code? i'd like to
> investigate
> this further.
>
> cheers
> stefan
>
> >
> > In the end, when I batched things up, I was able to ramp up the number
> of
> > nodes to what I wanted to test. Performance was acceptable once it was
> > loaded up - it is definately the save() operations that are the most
> > expensive. It was just very very difficult to build up my test data
> without
> > killing memory.
> >
> > Thanks everyone for your help, I have learned a lot about jackrabbit in
> the
> > meantime.
> >
> > On 9/1/06, Stefan Guggisberg <stefan.guggisberg@gmail.com> wrote:
> > >
> > > hi michael
> > >
> > > i quickly ran a test which successfully added 20k child nodes to the
> same
> > > parent (whether that's a useful content model is a different
> story...).
> > >
> > > here's the code i used to test:
> > >
> > >     Node parent = root.addNode("foo", "nt:unstructured");
> > >     for (int i = 1; i <= 20000; i++) {
> > >         parent.addNode("bar");
> > >         if (i % 1000 == 0) {
> > >             root.save();
> > >             System.out.println("added 1000 child nodes; total=" + i);
> > >         }
> > >     }
> > >
> > > note that save() is a relatively expensive operation; it therefore
> makes
> > > sense
> > > to batch multiple addNode etc calls (which are relatively
> inexpensive).
> > >
> > > please provide a simple self-contained test case that reproduces the
> > > behaviour
> > > you're describing.
> > >
> > > cheers
> > > stefan
> > >
> > > On 9/1/06, Michael Neale <michael.neale@gmail.com> wrote:
> > > > 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 <ntoper@gmail.com> 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 !!
> > > > >
> > > > >
> > > >
> > > >
> > >
> >
> >
>

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