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From Patrick Calahan <p...@bea.com>
Subject RE: V2 Store discussion...
Date Mon, 29 Sep 2003 18:47:56 GMT
At 11:31 AM 9/29/2003 -0700, you wrote:
>But Collections is thread safe for read operations, yes?  I assume those 
>bold letters said that access must be externally synchronized when 
>modifying a collection.  If this is the case, then users have come to 
>expect that read operations are thread safe.  This is the assumption we 
>are considering breaking.

I see.  Right, good point.
-p



>- Eric
>
>-----Original Message-----
>From: Patrick Calahan [mailto:pcal@bea.com]
>Sent: Monday, September 29, 2003 11:24 AM
>To: xmlbeans-dev@xml.apache.org; christopher.fry@bea.com; 
>xmlbeans-dev@xml.apache.org
>Subject: RE: V2 Store discussion...
>
>
>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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