On 6/29/06, Alexandru Popescu <[EMAIL PROTECTED]> wrote:
On 6/29/06, Tobias Bocanegra <[EMAIL PROTECTED]> wrote:
> the creation of the session is indeed lightweight. but there are
> caches attached to the session that increase performance (especially
> the CachingHierarchyManager). whenever you close (i.e. logout) the
> session, you loose the cached information.
>
> in a web-based environment, with anonymous, access, i would have a
> pool of connected (i.e. logged-in) jcr-sessions, that are used for
> every request. this pool can have the size of 1, as long you are only
> doing read-only access.
>
This sounds at the first glance interesting, but if the session keeps
caching nodes as different anonymous users are browsing around isn't
this gonna make the Session continuously grow?
jackrabbit uses memory-sensitive caches. take a look at
o.a.j.core.state.ItemStateReferenceCache for an example.
On the other hand, this looks pretty particular to Jackrabbit
implementation, because I don't think that the spec is mentioning
anything about caching the already loaded nodes.
jackrabbit is an *implementation* of the jsr 170 spec. caching is
an *implementation detail* that's why it's not mentionend in the
spec.
btw: any reasonable implementation will use some sort of caching.
cheers
stefan
./alex
--
.w( the_mindstorm )p.
---
(http://themindstorms.blogspot.com)
> as soon you have write access, possible several modifications over
> multiple requests, with a 'save' at the end, you need to attach the
> jcr-session to the j2ee-session, so that the transient changes don't
> get lost, or mixed up with different users.
>
> the simplest model, however is to complete every transaction in one
> request, creating and destroying one session for this purpose.
>
> regards, toby
> On 6/29/06, Alexandru Popescu <[EMAIL PROTECTED]> wrote:
> > Hi!
> >
> > Sorry for jumping to this discussion, but I am a little bit confused
> > by the comments (not those regarding Jackrabbit particular
> > implementation). My understanding till this moment is that Session
> > creation is not an expensive operation and so it is safe to open/close
> > a session for each user. Moreover, in case the Session-s are mostly
> > used in terms of read-only opperations I really don't see how my
> > understanding would be contradicted. I feel that it is more dangerous
> > the start to use Session in synchronized mode.
> >
> > As a quick note, my understanding (and not only mine, because I
> > discussed this with different people working/involved with JCR in the
> > past) is that JCR Session is somehow very similar to Hibernate
> > Session.
> >
> > Is my understanding/expectation completely wrong? If yes, than why?
> >
> > ./alex
> > --
> > .w( the_mindstorm )p.
> > ---
> > (http://themindstorms.blogspot.com)
> >
> >
> > On 6/29/06, Stefan Guggisberg <[EMAIL PROTECTED]> wrote:
> > > On 6/28/06, Ramachandra Sankuratri <[EMAIL PROTECTED]> wrote:
> > > > Hi
> > > >
> > > > If it has to support *read and write access* for multiple users, does
> > > > this mean that a new session has to be created for each user?
> > >
> > > yes, unless you synchronize the access to the shared Session
> > > and all dependant objects (Workspace, Node, Property etc.).
> > >
> > > note that this is not a jackrabbit-specific limitation;
> > > see "7.5 Thread-Safety Requirements" of the jsr 170 spec:
> > >
> > > <quote>
> > > As a consequence, an application which concurrently or sequentially
> > > operates against objects having affinity to a particular Session
> > > through more than one thread must provide synchronization sufficient
> > > to ensure no more than one thread concurrently operates against that
> > > Session and changes made by one thread are visible to other threads.
> > > </quote>
> > >
> > > cheers
> > > stefan
> > >
> > > >
> > > > Thanks
> > > > Chandu
> > > >
> > > > -----Original Message-----
> > > > From: Stefan Guggisberg [mailto:[EMAIL PROTECTED]
> > > > Sent: Wednesday, June 28, 2006 12:57 PM
> > > > To: [email protected]
> > > > Subject: Re: Newbie Question - Performance
> > > >
> > > > On 6/28/06, Vijay Pandey <[EMAIL PROTECTED]> wrote:
> > > > > Hi,
> > > > >
> > > > > I am planning to use Jackrabbit and for a great # of users we only
> > > > need to
> > > > > provide read only access and i was reading on the wiki section abvout
> > > > > performance, it says 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.
> > > > > ----------------------------------------------------------------
> > > > >
> > > > > Does it mean to say that 'session' is thread safe at method level for
> > > > read
> > > > > only operations , or do we have to synchronize the call on session? or
> > > > do
> > > > > you think should we have a pool of read only sessions ?
> > > >
> > > > you can assume that Session (at least the jackrabbit implementation)
> > > > is thread-safe if it is used for *reading only*.
> > > >
> > > > cheers
> > > > stefan
> > > >
> > > > >
> > > > > Thanks
> > > > > Vijay
> > > > >
> > > > >
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>
>
> --
> -----------------------------------------< [EMAIL PROTECTED] >---
> Tobias Bocanegra, Day Management AG, Barfuesserplatz 6, CH - 4001 Basel
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