Weel I thought that
Rich36's benchmark was a little flawed, but the results turned out, not the way I thought.
The benchmark below uses his code(modified), and demonstrates that there is considerable overhead to using %ENV (I hope I did it right).
Check it out (readmore)
#!/usr/bin/perl -w
use strict;
use Benchmark;
## I eliminated the print statements used inside the benchmark
## they weren't really useful/neccessary
## the speed diff comes from the fact that %ENV really is %main::ENV
## and $foo is not in main
## I will show that now by adding a $foo in main
## also, %ENV is a hash, so I have made %foo and %FOO a hash
## in fact, I made them copies of %ENV
## that way we get into no funky business
sleep 1;
{
# Start the benchmark
$ENV{PATH}=1;
my $start = new Benchmark;
for(1..100000) {
$ENV{PATH}++;
}
# End the program and return the Benchmark time
my $end = new Benchmark;
print "Processing time was...\n";
print timestr(timediff($end, $start)) . "\n";
print scalar(%ENV)."\n";
}
sleep 1;
{
my %foo = map { $_ => $ENV{$_} } keys %ENV;
$foo{PATH} = 1;
# Start the benchmark
my $start = new Benchmark;
for(1..100000) {
$foo{PATH}++;
}
# End the program and return the Benchmark time
my $end = new Benchmark;
print "Processing time was...\n";
print timestr(timediff($end, $start)) . "\n";
print scalar(%foo)."\n";
}
sleep 1;
{
use vars qw / %FOO /;
%FOO = map { $_ => $ENV{$_} } keys %ENV;
$FOO{PATH} = 1;
# Start the benchmark
my $start = new Benchmark;
for(1..100000) {
$FOO{PATH}++;
}
# End the program and return the Benchmark time
my $end = new Benchmark;
print "Processing time was...\n";
print timestr(timediff($end, $start)) . "\n";
print scalar(%FOO)."\n";
}
__END__
F:\dev>perl -le"print `perl benchy.txt`,' ' for 1..10"
Processing time was...
7 wallclock secs ( 7.05 usr + 0.00 sys = 7.05 CPU)
Processing time was...
1 wallclock secs ( 0.60 usr + 0.00 sys = 0.60 CPU)
Processing time was...
0 wallclock secs ( 0.53 usr + 0.00 sys = 0.53 CPU)
^C
F:\dev>perl -le"print `perl benchy.txt`,' ' for 1..10"
Processing time was...
7 wallclock secs ( 7.30 usr + 0.00 sys = 7.30 CPU)
20/32
Processing time was...
1 wallclock secs ( 0.55 usr + 0.00 sys = 0.55 CPU)
23/64
Processing time was...
0 wallclock secs ( 0.65 usr + 0.00 sys = 0.65 CPU)
23/64
Processing time was...
7 wallclock secs ( 7.27 usr + 0.00 sys = 7.27 CPU)
20/32
Processing time was...
1 wallclock secs ( 0.54 usr + 0.00 sys = 0.54 CPU)
23/64
Processing time was...
0 wallclock secs ( 0.64 usr + 0.00 sys = 0.64 CPU)
23/64
Processing time was...
7 wallclock secs ( 7.19 usr + 0.00 sys = 7.19 CPU)
20/32
Processing time was...
1 wallclock secs ( 0.55 usr + 0.00 sys = 0.55 CPU)
23/64
Processing time was...
1 wallclock secs ( 0.63 usr + 0.00 sys = 0.63 CPU)
23/64
Processing time was...
7 wallclock secs ( 7.21 usr + 0.00 sys = 7.21 CPU)
20/32
Processing time was...
0 wallclock secs ( 0.54 usr + 0.00 sys = 0.54 CPU)
23/64
Processing time was...
1 wallclock secs ( 0.63 usr + 0.00 sys = 0.63 CPU)
23/64
Processing time was...
7 wallclock secs ( 7.15 usr + 0.00 sys = 7.15 CPU)
20/32
Processing time was...
1 wallclock secs ( 0.55 usr + 0.00 sys = 0.55 CPU)
23/64
Processing time was...
0 wallclock secs ( 0.63 usr + 0.00 sys = 0.63 CPU)
23/64
Processing time was...
7 wallclock secs ( 7.30 usr + 0.00 sys = 7.30 CPU)
20/32
Processing time was...
1 wallclock secs ( 0.54 usr + 0.00 sys = 0.54 CPU)
23/64
Processing time was...
1 wallclock secs ( 0.64 usr + 0.00 sys = 0.64 CPU)
23/64
Processing time was...
8 wallclock secs ( 7.19 usr + 0.00 sys = 7.19 CPU)
20/32
Processing time was...
0 wallclock secs ( 0.54 usr + 0.00 sys = 0.54 CPU)
23/64
Processing time was...
1 wallclock secs ( 0.63 usr + 0.00 sys = 0.63 CPU)
23/64
Processing time was...
7 wallclock secs ( 7.30 usr + 0.00 sys = 7.30 CPU)
20/32
Processing time was...
1 wallclock secs ( 0.54 usr + 0.00 sys = 0.54 CPU)
23/64
Processing time was...
0 wallclock secs ( 0.63 usr + 0.00 sys = 0.63 CPU)
23/64
Processing time was...
7 wallclock secs ( 7.23 usr + 0.00 sys = 7.23 CPU)
20/32
Processing time was...
1 wallclock secs ( 0.53 usr + 0.00 sys = 0.53 CPU)
23/64
Processing time was...
1 wallclock secs ( 0.63 usr + 0.00 sys = 0.63 CPU)
23/64
Processing time was...
8 wallclock secs ( 7.21 usr + 0.00 sys = 7.21 CPU)
20/32
Processing time was...
0 wallclock secs ( 0.54 usr + 0.00 sys = 0.54 CPU)
23/64
Processing time was...
1 wallclock secs ( 0.64 usr + 0.00 sys = 0.64 CPU)
23/64
F:\dev>
