I'm working on a mathematical model that uses data generated from XFOIL, a popular aerospace tool used to find the lift and drag coefficients on airfoils.
I have a Perl script that calls XFOIL repeatedly with different input parameters to generate the data I need. I need XFOIL to run 5,600 times, at around 100 seconds per run, soabout 6.5 days to complete.
I have a quad-core machine, but my experience as a programmer is limited, and I really only know how to use basic Perl.
I would like to run four instances of XFOIL at a time, all on their own core. Something like this:
while ( 1 ) {
for ( i = 1..4 ) {
if ( ! exists XFOIL_instance(i) ) {
start_new_XFOIL_instance(i, input_parameter_list);
}
}
}
So the program is checking (or preferably sleeping) until an XFOIL instance is free, when we can start a new instance with the new input parameter list.
Try Parallel::ForkManager. It's a module that provides a simple interface for forking off processes like this.
Here's some example code:
#!/usr/bin/perl
use strict;
use warnings;
use Parallel::ForkManager;
my @input_parameter_list =
map { join '_', ('param', $_) }
( 1 .. 15 );
my $n_processes = 4;
my $pm = Parallel::ForkManager->new( $n_processes );
for my $i ( 1 .. $n_processes ) {
$pm->start and next;
my $count = 0;
foreach my $param_set (@input_parameter_list) {
$count++;
if ( ( $count % $i ) == 0 ) {
if ( !output_exists($param_set) ) {
start_new_XFOIL_instance($param_set);
}
}
}
$pm->finish;
}
$pm->wait_all_children;
sub output_exists {
my $param_set = shift;
return ( -f "$param_set.out" );
}
sub start_new_XFOIL_instance {
my $param_set = shift;
print "starting XFOIL instance with parameters $param_set!\n";
sleep( 5 );
touch( "$param_set.out" );
print "finished run with parameters $param_set!\n";
}
sub touch {
my $fn = shift;
open FILE, ">$fn" or die $!;
close FILE or die $!;
}
You'll need to supply your own implementations for the start_new_XFOIL_instance and the output_exists functions, and you'll also want to define your own sets of parameters to pass to XFOIL.