Script Startup Time

gnu@perl has asked for the wisdom of the Perl Monks concerning the following question:

I have a script (relevent code below) that evaluates some command line options. One of these options prints out the version and exits. The thing I don't like is that it takes a few seconds to print out the version. Not a big deal, but a little irritating.

I know the reason is all of the modules being 'use'ed. I know I could explicitely import the important parts of the modules and that may help, but I'm not sure. If I comment out all the 'use' lines except for 'use Getopt::Long' the './program.pl --version' comes back immediately. This is the type of performance I would like when the whole thing is done.

Does anyone have any ideas on how I could speed this up?

TIA, gnu.

code below

use strict;
use IO::Select;
use IO::Socket;
use Fcntl;
use POSIX qw(:signal_h WNOHANG);
use Net::SNMP;
use DBI;
use Sys::Hostname;
use Getopt::Long qw(:config pass_through );

$|++;
umask(0177);

(my $VERSION  = '$Revision: 1.23 $') =~ s/\$(.+) \$/$1/;
my $MAXCHILDREN       = 10;
my $inputFile         =  "./mping.lookup";
my $path              =  "./unix_socket";
my $OID               =  '.1.3.6.1.4.1.15102.2.1.1.1';
my $interval          =  60;
my %source;
my %failures;
my $dump              = 0;
my $run               = 0;
my $version           = 0;
my %options           = ( 'version'    => \$version,
                          'children=i' => \$MAXCHILDREN,
                          'input'      => \$inputFile,
                          'socket'     => \$path,
                          'dump'       => \$dump,
                          'run'        => \$run,
                        );

$SIG{TERM} = $SIG{INT}  = sub { unlink $path; exit 0 };

GetOptions(%options);

if (${$options{dump}}) {
   print $VERSION,"\n";
   print "There are $MAXCHILDREN child processes by default\n";
   print "Input file is ",${$options{input}},":\n";
   print "Comm socket is ",${$options{socket}},":\n";
   exit if ! ${$options{run}};
}

if (${$options{version}}) {
   print $VERSION,"\n";
   exit if ! ${$options{run}};
}
[download]

Comment on Script Startup Time Download Code

Replies are listed 'Best First'.
Re: Script Startup Time by liz (Monsignor) on Sep 17, 2003 at 17:49 UTC
It's all a matter of order and where to BEGIN: ;-) use strict; my $VERSION; my $MAXCHILDREN; use Getopt::Long qw(:config pass_through ); BEGIN { ($VERSION = '$Revision: 1.23 $') =~ s/\$(.+) \$/$1/; $MAXCHILDREN = 10; my %options = ( 'version' => \$version, 'children=i' => \$MAXCHILDREN, 'input' => \$inputFile, 'socket' => \$path, 'dump' => \$dump, 'run' => \$run, ); GetOptions(%options); if (${$options{dump}}) { print $VERSION,"\n"; print "There are $MAXCHILDREN child processes by default\n"; print "Input file is ",${$options{input}},":\n"; print "Comm socket is ",${$options{socket}},":\n"; exit if ! ${$options{run}}; } if (${$options{version}}) { print $VERSION,"\n"; exit if ! ${$options{run}}; } } use IO::Select; use IO::Socket; use Fcntl; use POSIX qw(:signal_h WNOHANG); use Net::SNMP; use DBI; use Sys::Hostname; $\|++; umask(0177); my $inputFile = "./mping.lookup"; my $path = "./unix_socket"; my $OID = '.1.3.6.1.4.1.15102.2.1.1.1'; my $interval = 60; my %source; my %failures; my $dump = 0; my $run = 0; my $version = 0; $SIG{TERM} = $SIG{INT} = sub { unlink $path; exit 0 }; [download] This is untested. But the basic idea is that the code you need to execute so you can show the Version info, is moved to a BEGIN {} block, before you load any of the other modules you need. Liz	[reply] [d/l]
Re: Re: Script Startup Time by gnu@perl (Pilgrim) on Sep 17, 2003 at 18:02 UTC
Yeah, I had that, but I like to try and keep all my 'use' lines together. This does work by the way. Thanks.	[reply]
Re: Script Startup Time by sandfly (Beadle) on Sep 17, 2003 at 21:11 UTC
merlyn suggested the use of autouse in a different node. It looks like a better fit here. From the documentation, it appears to do exactly what you want - defers the cost of `use`ing modules until you need them. (I have never used autouse, so I can't say how reliable it is.)	[reply] [d/l]
Re: Script Startup Time by ronzomckelvey (Acolyte) on Sep 24, 2003 at 03:58 UTC
Can't you just put the use statements inside of an `eval()` statement? I've got code that doesn't know what modules to load until it actaully runs, and loads them through the eval. ronzo	[reply] [d/l]


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