XOM API for Processing XML with Java

[Wolfgang Hoschek <whoschek AT lbl.gov>]

I've seen that presentation some years ago, Steve.

There are many cases where cost/benefit and prize/performance do not 
pay off, no doubt. Gains tend to be high initially, then level off 
beyond some point, with little ROI. But there are no universal truths. 
Fruits often hang low, they accumulate and, quite possibly, multiply. 
Try running a throughput app with JDK 1.3 client VM and a normal 
parser, then try running with 1.5 server VM and a binary codec. With a 
little luck, there may well be 2 orders of magnitude speedup here.

Let me give you a funny thanksgiving example:

You have a Grid data center, your apps are grinding away on 
data-intensive problems. The primary measure of success is how much 
data you can process, and the better you are the more data the apps 
will throw at you: the desire is for ever higher frequencies of 
measurement, ever more accurate algorithms, ever more timely results - 
with hard work and little luck there might be a nobel prize around the 
corner.

You have 10000 CPUs, 3 Petabytes of disk caches and 20 Petabytes of 
robotic tape (the disks are just caches for the tapes), funky 
transatlantic links to similar folks (who are your collaborators but in 
a sense also your competitors). That translates to a large building 
with a substantial energy bill for power and cooling, regular 
hardware-failures because of a large N everywhere, quite a few 
technicians, and some challenges in scalable systems administration. 
Now suggest to high-level management "no particular need to try being 
efficient; just relax, everything will take care of itself soon", 
indirectly implying that we could just get away with standards based 
off-the-shelf commodity technology, or next year's version of it. It 
just happens to require another 90000 CPUs, plus disks, plus switches, 
plus staff, plus a new research project to figure out how we can 
actually keep the baby alive without imploding, etc.

For example, imagine the truck loads of spare parts arriving every day, 
with the technicians replacing failed disks pretty much all day long, 
every day, as a matter of routine. Each time those poor chaps walk back 
and forth between the truck and the hall they pass by a plastic sticker 
on the entrance door that proudly pronounces the "standards, 
off-the-shelf technology and next year's hardware are key to success" 
mantra. Then they look over to the office window of the mantra's 
inventor, and shake heads. :-)

Don't take it seriously, have a nice thanksgiving, and enjoy...
Wolfgang.

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Wolfgang Hoschek                  |   email: whoschek AT lbl.gov
Distributed Systems Department    |   phone: (415)-533-7610
Berkeley Laboratory               |   http://dsd.lbl.gov/~hoschek/
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On Nov 25, 2004, at 1:55 PM, Steve Loughran wrote:

> On Thu, 25 Nov 2004 12:50:55 -0800, Wolfgang Hoschek 
> <whoschek AT lbl.gov> wrote:
> > Turns out it actually amounts to the same effect. No improvement 
> > there.
> > Maybe i'm just overworked...
> > Wolfgang.
>
> Maybe you're just trying too hard
>
> http://www.cs.umd.edu/~pugh/IsCodeOptimizationRelevant.pdf