[jdom-interest] Thread questions regarding JDOM SAXBuiler?

[Mike Brenner]

I AGREE. Would Laurent please rerun those exact tests
without the AgressiveHeap parameter so we can see what
that parameter did?



David Wall wrote:
> 
> That's really interesting, though it also appears you've set some GC
> arguments as well (I'm not familiar with them).  But the GC did sound like
> it might be a problem, though in the end, they both should have created the
> same large XML document objects that would then be discarded.  But this
> continues to show 'reuse==true' creates a performance hit.  Why have an
> option that appears to slow things down, and even the javadocs indicate it
> would slow things down.  What's the purported benefit of doing reuse==true?
> 
> David
> 
> ----- Original Message -----
> From: "Laurent Bihanic" <laurent.bihanic at atosorigin.com>
> To: "Per Norrman" <per.norrman at austers.se>
> Cc: "David Wall" <d.wall at computer.org>; <jdom-interest at jdom.org>
> Sent: Wednesday, September 01, 2004 7:54 AM
> Subject: Re: [jdom-interest] Thread questions regarding JDOM SAXBuiler?
> 
> >
> > I don't think your test tool performs enough iterations for the result to
> be
> > reliable due to garbage collector side-effects.
> > I modified your tool to run 1000 iterations instead of 20 :
> >
> > java -XX:+AggressiveHeap large.ThreadedReader
> >
> > Reuse=true      size=21837      time: 42497
> > Reuse=false     size=21837      time: 40796
> >
> > Reuse=true      size=1927       time: 3403
> > Reuse=false     size=1927       time: 11125
> >
> > Reuse=true      size=21837      time: 28469
> > Reuse=false     size=21837      time: 35527
> >
> > Reuse=true      size=43469      time: 57238
> > Reuse=false     size=43469      time: 63963
> >
> > Reuse=true      size=325632     time: 428557
> > Reuse=false     size=325632     time: 443638
> >
> > ...
> >
> >
> > Per Norrman wrote:
> >
> > > Hi,
> > >
> > > I meant to make the program self-cotained but missed the dependency
> > > on the concurrent jar. Here's a new version. You should run the test
> > > in your environment to confirm the results.
> > >
> > > Yes, documents are discarded after being built. There are many
> variations
> > > you can do in a test like this. My guess is that it's
> String/StringBuffer
> > > handling in SAXBuilder and/or Xerces that accounts for the resuts.
> > >
> > > A typical output in my environment (P3, 850Mhz, Dell Latitude C600):
> > >
> > > Reuse=true    size=21731    time: 5720
> > > Reuse=false    size=21731    time: 2215
> > >
> > > Reuse=true    size=1918    time: 200
> > > Reuse=false    size=1918    time: 300
> > >
> > > Reuse=true    size=21731    time: 1200
> > > Reuse=false    size=21731    time: 2065
> > >
> > > Reuse=true    size=43259    time: 3697
> > > Reuse=false    size=43259    time: 2663
> > >
> > > Reuse=true    size=324070    time: 25435
> > > Reuse=false    size=324070    time: 22233
> > >
> > > Reuse=true    size=756109    time: 66417
> > > Reuse=false    size=756109    time: 53194
> > >
> > > The first run should be disregarded. Used for warming-up.
> > >
> > > /pmn
> 
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