[ expat-Bugs-566238 ] 1.95.3: xmlwf startup time much longer

Fri Jul 12 08:21:10 2002

Bugs item #566238, was opened at 2002-06-08 17:29
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Category: Build control
Group: None
Status: Open
Resolution: None
Priority: 6
Submitted By: Rolf Ade (pointsman)
Assigned to: Greg Stein (gstein)
Summary: 1.95.3: xmlwf startup time much longer

Initial Comment:

At least at my linux box, I seems that the new way of
starting xmlwf - with a shell wrapper - heavily
increases the startup time of xmlwf.

For most people, this may be a really minor problem (it
isn't even a big one for me, though). But if you check
a lot of really small xml files with xmlwf in  one
commandline or a shell script, this is very notable. 

I've noticed it, while checking the (very small) test
files of the OASIS test suite. My shell scripts, that
does this, needed up to 10 times (!) longer, to finished.

To be sure, it's really the startup time, I checked
xmlwf against some bigger XML files (around 30 Mbyte)
and found only minor speed differences between 1.95.2
and 1.95.3. It seems, 1.95.3 is around 6 or 7 percent
slower than 1.95.2 (I've substracted the mesured longer
startup time of the 1.95.3 xmlwf from the running time,
befor calculation.)

rolf

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>Comment By: Rolf Ade (pointsman)
Date: 2002-07-12 15:20

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Greg,

well, you got me. Yes, I observed the slowdown of xmlwf,
while running it from the build copy. Yes, after
installation, there isn't a shell wrapper anymore, just the
xmlwf binary. I'm sorry about any irritation, I've triggered.

But - not to distract from my mistake, but because I'm
really a bit worried about - even beside this shell wrapper
thing (which is not a problem, I confirm)  expat is getting
slower and slower, from version to version. It's not
dramatic, but it sums up.

I've just done some tests, that confirmed that again. To
give some concrete numbers (on a linux 2.2.13, PII 333MHz,
384 MByte memory) from checking a around 100 MByte big XML
file with the according xmlwf tools (I ensured, that the
file is in the system cache)

With 1.92.3:

real    0m12.108s
user    0m11.360s
sys     0m0.660s

With 1.92.2:

real    0m11.152s
user    0m10.450s
sys     0m.670s

With James Clarks 1.2final:

real    0m9.471s
user    0m9.360s
sys     0m0.090s

This numbers are typical for all XML files, I've done this
comparson. To sum up the results, this is a solid 25 percent
slow down from 1.2 to 1.92.3.

Remarkable is the much greater sys part for the 1.92.x
versions. This may because of changed I/O code in the xmlwf
tool (haven't check this). But even  without this, there's a
notable slow down.

It's not dramatic, as said. Expat is still the fastest
compliant XML parser, I know. But to say it frankly, one of
the major points of using expat (if not the major point) is
simply its speed.

Some slow down may be unavoidable (for example due to the
reasent fix for better detection of invalid XML chars), but
I would love, if someone checks this - and the speed of
current versions in general - with a critical eye.

rolf

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Comment By: Greg Stein (gstein)
Date: 2002-07-11 17:10

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Rolf,

Was your slower time measured against xmlwf out of the build
tree, or an installed copy? As far as I can tell, we never
install the shell script wrapper. Within the build tree, it
will always be present (the first run will be slow while it
links, then it should be faster (but not as fast as without
the shell script, of course))

Anyways... we need to find out if your observation was for
the build or installed copy of xmlwf.

thx.

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Comment By: Fred L. Drake, Jr. (fdrake)
Date: 2002-06-29 15:28

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This is painful, but not enough to hold up a bugfix release.

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Comment By: Fred L. Drake, Jr. (fdrake)
Date: 2002-06-26 04:58

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Ugh!  This is heinous!  The crufty libtool wrapper should
never be installed, and even says so itself.

Greg, can you fix this soon?

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