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From Patrick Calahan <p...@bea.com>
Subject RE: V2 Store discussion...
Date Mon, 29 Sep 2003 18:23:48 GMT
At 10:25 AM 9/29/2003 -0700, Eric Vasilik wrote:
>Did the JDK make the map operations safe in the face of multiple threads 
>doing operations which modify the map?   I

Yeah, early classes like java.util.Hashtable and Vector were internally 
synchronized with respect to reads and writes.

It may be interesting to note that when Collections came along, most of the 
classes came with a note in big bold letters that access to them must be 
externally synchronized.  Given that Collections has been very 
well-received and is probably the single most-used API in the JDK, I wonder 
how much of a requirement threadsafe XMLBeans really is going to be for users.

-p



>The problem I'm facing with the architecture of the store is one where it 
>seems that I have to trade off synchronize/finalize with object 
>creation.  I've found that creating fewer objects benefits performance, 
>but renders read operations thread unsafe.
>
>Dave and I talked this morning about this and we believe that performance 
>of the store is so important that making the store thread safe (for read 
>operations) will be optional and *off* by default.
>
>Any thoughts?  Any confusion about this trade off?
>
>- Eric
>
>-----Original Message-----
>From: Chris Fry [mailto:christopher.fry@bea.com]
>Sent: Monday, September 29, 2003 9:55 AM
>To: xmlbeans-dev@xml.apache.org; Eric Vasilik
>Subject: RE: V2 Store discussion...
>
>
>I think you should be careful not to make the same mistakes that the JDK
>made early on with the map implementations.  The early map implementations
>were thread safe and very slow, so no-one used them.  It might be best to
>have two implementations of the store (one that is thread safe & one that
>isn't) so that users can choose safety over performance.  Or performance if
>they know the data will only be read in a single thread as may be the case
>in WS-invocations...
>
>-C
>
> > -----Original Message-----
> > From: David Bau [mailto:david.bau@bea.com]
> > Sent: Monday, September 29, 2003 8:27 AM
> > To: Eric Vasilik
> > Cc: xmlbeans-dev@xml.apache.org
> > Subject: V2 Store discussion...
> >
> >
> > Eric, was thinking about the threading/object creation etc
> > issues over the
> > weekend.
> >
> > Another interesting issue: currently we use a finalizer on
> > cursors, but
> > finalizers seem to be fairly expensive, so apps that spew out
> > lots and lots
> > of cursors have issues.  I wonder what problems we'd have to
> > deal with in
> > order to eliminate the finalizer, and whether or not that
> > would be possible,
> > or if it would come into conflict with some of the other
> > parameters of the
> > problem just like synchronization?
> >
> > David
> >
> >
> > -
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> > Apache XMLBeans Project -- URL: http://xml.apache.org/xmlbeans/
> >
> >
>
>
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