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From Edgar Poce <edgarp...@gmail.com>
Subject Re: Performance
Date Wed, 12 Oct 2005 19:44:15 GMT
hi

  I haven't used jackrabbit with a huge amount of data yet but I did
run some tests and have some impressions I'd like to share, hopefully
someone will correct me if I'm misleading you.

In most cases I agree with David and Marcel, who pointed that
jackrabbit doesn't seem to affected by the number of nodes. However, I
think that in order to maintain the performance you should take into
account some considerations on the usage that might affect it
seriously.

Regarding the tree structure. Since each parent holds references to
its children each time you add a child the parent becomes heavier. It
causes a degradation in performance for write operations according to
the number of children. I think it's better to use a deep hierarchy
rather than a flat structure. I would recommend you to do some testing
to establish the limits that suits your needs.

Regarding the session handling. A transient item storage is bound to
each session. The transient storage contains its own cache of nodes
that are connected to the underlying persistent storage. The thing is
that each time a node is modified, all the cached transient nodes are
notified. Therefore the more open sessions you have the more expensive
the write operation will be. I think you should try each session to
perform write operations on nodes which are not under heavy load from
other sessions. e.g. I think it's good practice to avoid write
operations in the root node if the repository is to be accessed by a
high number of sessions. I also think that it's a good practice to
share a single anonymous session for read only access if possible, it
would reduce the time that write actions will take.

Regarding concurrency. Currently jackrabbit lacks fine grained locking
for write operations. So, if the repository will be under heavy load I
would consider an approach like the one used in Magnolia, I'm not sure
if they still use it but the last time I checked they had a repository
for authoring and another for publishing.

br,
edgar


On 10/12/05, Eugeny N Dzhurinsky <eugenydzh@jdevelop.com> wrote:
> Hi there!
> We are developing CMS, and we need to learn a bit more about the performance
> of JackRabbit. The thing is I didn't find anything about the performance
> neither in wiki, nor in documentation,
>
> To be more specific, we are wandering about the performance JackRabbit
> could have, for example, working with several hundred thousands nodes/properties
> and very deep nodes tree?
>
> --
> Eugene N Dzhurinsky
>

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