[Mod-pubsub-general] running mod-pubsub under mod_perl

[<kra...@ca...>]

Here's what I had to do to get mod_pubsub working under mod_perl,
which used to speed it up by about an order of magnitude.

1. install mod_perl
2. ensure it's loaded by Apache; in httpd.conf, something like:
    LoadModule perl_module /usr/lib/apache/1.3/mod_perl.so
3. ensure the kn_events dir is writable by the apache user; for me, this was
    sudo chown -R www-data kn_events
   Joyce reports that making kn_events recursively world-writable seems to work
   too, but I don't recommend that.

Some Apache setups might have to loosen up their AllowOverride
restrictions on .htaccess files to get things to work; as an
alternative, you can put the relevant bits from cgi-bin/.htaccess
(which handle *.cgi with Apache::Registry) into your httpd.conf.

So on my 300MHz laptop, pubsub_test.cgi now finishes in 104 seconds;
before, running as an actual CGI script, it took 278 seconds.  This
dramatically understates the speed improvement of pubsub.cgi, though;
it sleeps for 49 of those seconds, so it spends 53 seconds instead of
229 seconds doing things other than sleeping.  Not as big a speedup as
I'd hoped.

Another thing to note: with mod_perl, my CPU loads stayed relatively
low, while running mod_pubsub as a CGI script, my CPU load stayed at
100%.

The mail sensor and replay tests didn't work for me at first; I'd
copied the cgi-bin dir into my public_html dir, but I hadn't copied
the kn_sense directory, and those tests use programs in kn_sense.

Oh, and if you run out of disk space (easy to do --- each run of
pubsub_test.cgi chomps 11 megs on my ext3fs!) the test suite tends to
hang.  Dunno why that happens.

In Mozilla, kn_apps/ping2 reports an average ping time of 766 ms,
which seems outrageously horrible to me, and 13 Hz event throughput.
Without mod_perl, I get an average ping time of 1909 ms and 14.7 Hz
event throughput.

Ben suggested that maybe Mozilla's inherent slowness was causing the
slowdown, so I tried the test with Netscape 4.7.  Talking to the same
server (using mod_perl, of course) over 802.11b, it got 276ms and
38Hz.  Still seems slow to me.

We should probably fix Mozilla.

Hope this helps someone.

-- 
<kr...@po...>       Kragen Sitaker     <http://www.pobox.com/~kragen/>
Edsger Wybe Dijkstra died in August of 2002.  The world has lost a great
man.  See http://advogato.org/person/raph/diary.html?start=252 and
http://www.kode-fu.com/geek/2002_08_04_archive.shtml for details.