Greetings mod_perl list,
I've been having fun with dtrace, and I most recently used it to see
what files are being accessed by mod_perl during requests. I've
preloaded all the modules in my application that I know about into
startup.pl, but when I startup my httpd server and make a request, I got
some unexpected results.
sudo rwsnoop -n httpd
501 3509 httpd R 405 http.pm
501 3509 httpd R 0 http.pm
501 3509 httpd R 2239 _server.pm
501 3509 httpd R 0 _server.pm
501 3509 httpd R 4096 _generic.pm
501 3509 httpd R 1563 _generic.pm
501 3509 httpd R 0 _generic.pm
501 3509 httpd R 2052 _query.pm
501 3509 httpd R 0 _query.pm
Those files showed up during the first request, but not subsequent
requests. A little digging showed that this was the URI::http module
being loaded at runtime, since my application uses URI. But I
'use URI ();' in my startup.pl - apparently URI::http isn't being
loaded. Looks like URI requires http.pm at runtime:
URI.pm:
# check we actually have one for the scheme:
unless (@{"${ic}::ISA"}) {
# Try to load it
eval "require $ic";
Fine and good, I added URI::http to my startup.pl and those file stats
went away. There were some other offenders too though:
501 3508 httpd R 4096 utf8_heavy.pl
501 3508 httpd R 4096 utf8_heavy.pl
501 3508 httpd R 2323 utf8_heavy.pl
501 3508 httpd R 0 utf8_heavy.pl
501 3508 httpd R 4096 PVA.pl
501 3508 httpd R 4096 PVA.pl
501 3508 httpd R 4096 PVA.pl
501 3508 httpd R 4096 PVA.pl
501 3508 httpd R 1952 PVA.pl
501 3508 httpd R 0 PVA.pl
501 3508 httpd R 1279 Exact.pl
501 3508 httpd R 0 Exact.pl
501 3508 httpd R 4096 Canonical.pl
501 3508 httpd R 4096 Canonical.pl
501 3508 httpd R 4096 Canonical.pl
501 3508 httpd R 4096 Canonical.pl
501 3508 httpd R 4096 Canonical.pl
501 3508 httpd R 1529 Canonical.pl
501 3508 httpd R 0 Canonical.pl
501 3508 httpd R 4096 Fold.pl
501 3508 httpd R 4096 Fold.pl
501 3508 httpd R 4096 Fold.pl
501 3508 httpd R 1709 Fold.pl
501 3508 httpd R 0 Fold.pl
501 3508 httpd R 324 SpacePer.pl
501 3508 httpd R 0 SpacePer.pl
Hmm, I use Encode in my application, and preload it but why aren't those
files being loaded at startup?
I tried adding 'use utf8 ();' to startup.pl and it had no effect.
So I added the following require directives to startup.pl
require 'utf8_heavy.pl';
require 'unicore/PVA.pl';
require 'unicore/Exact.pl';
require 'unicore/Canonical.pl';
require 'unicore/To/Fold.pl';
require 'unicore/lib/gc_sc/SpacePer.pl';
and everything but Fold.pl and SpacePer.pl was loaded at startup. The
remainind dtrace lines:
501 3687 httpd R 4096 Fold.pl
501 3687 httpd R 4096 Fold.pl
501 3687 httpd R 4096 Fold.pl
501 3687 httpd R 1709 Fold.pl
501 3687 httpd R 0 Fold.pl
501 3687 httpd R 324 SpacePer.pl
501 3687 httpd R 0 SpacePer.pl
I'm not sure why these programs are still loaded at runtime, but I've
probably managed to save about 40k or so per process by preloading these
modules I am guessing. Not much but every byte counts.
If anyone has the unicode foo to tell me why those programs aren't
loading, I'd be very interested in knowing.
- Fred
