On Jan 11, 6:50 am, Massimiliano Mirra <hyperstr
...@gmail.com> wrote:
> I came across this while writing a templating engine for Helma.
> "js.jar" is built from a fresh cvs.mozilla.org checkout,
> "js-noxmlbeams.jar" is the same without
> org/mozilla/javascript/xml/impl/xmlbeans/ (thus using
> .../javascript/xmlimpl/), "js" is spidermonkey 1.8, java is j2se6,
> time is in msecs:
> bard@yokai:/tmp/w/seethrough_helma$ java -Djava.compiler=NONE -jar
> js.jar -opt 9 e4x_bm.js
> times per run: 10000
> run #0 total time: 42596
> run #1 total time: 48355
> run #2 total time: 51056
> run #3 total time: 52297
> bard@yokai:/tmp/w/seethrough_helma$ java -Djava.compiler=NONE -jar js-
> noxmlbeans.jar -opt 9 e4x_bm.js
> times per run: 10000
> run #0 total time: 38487
> run #1 total time: 45523
> run #2 total time: 43726
> run #3 total time: 46889
> bard@yokai:/tmp/w/seethrough_helma$ js e4x_bm.js
> times per run: 10000
> run #0 total time: 18
> run #1 total time: 6
> run #2 total time: 19
> run #3 total time: 6
> bard@yokai:/tmp/w/seethrough_helma$ cat e4x_bm.js
> function bm(fn, times) {
> times=times||100;
> var start=Date.now();
> for(var i=0;i<times;i++)
> fn();
> return (Date.now() - start);
> }
> var runs = 4;
> var times = 10000;
> print('times per run: ' + times);
> for(var i=0;i<runs; i++) {
> var total = bm(function(){ <test/> }, times);
> print('run #' + i + ' total time: ' + total);}
Performing some unscientific instruction sampling (i.e., pausing Rhino
while running your test in the debugger and looking at the stack), it
looks like we're spending most of our time in
com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse().
So I don't have much idea how to improve this short of switching to
yet another XML parser.
I did notice that we were creating a DocumentBuilder from scratch
every time, so I created a simple DocumentBuilder pool. This saved
about 23% on your test case, which is a nice speedup but still leaves
us a couple of orders of magnitude slower than SpiderMonkey for this
case.
--N
