comment on

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>
[download]

______crazyinsomniac_____________________________
Of all the things I've lost, I miss my mind the most.
perl -e "$q=$_;map({chr unpack qq;H*;,$_}split(q;;,q*H*));print;$q/$q;"

In reply to (crazyinsomniac: %ENV equals overhead) Re: $ENV {'FOO'} $foo by crazyinsomniac
in thread $ENV {'FOO'} $foo by coreolyn

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