Someone was asking on a list why their program wasn't getting expected results (had to due with "unit of measurement" inconsistencies). But to test they'd written the program in python -- for 9 threads, they got < 2 cores utilization. I was curious how perl would do. So I tried to follow the python structure as much as possible.

First the programs, python: 

#!/usr/bin/python
import operator
import hashlib
from threading import Thread

def ticks_all():
  with open('/proc/stat') as f:
    cpu = f.readline().split()
    return (int(cpu[1]), int(cpu[3]))

def ticks_process():
  with open('/proc/self/stat') as f:
    cpu = f.readline().split()
    return (int(cpu[13]), int(cpu[14]))

def do_work():
  d = hashlib.md5()
  d.update('nobody inspects')
  for i in xrange(0, 10000000):
    d.update(' the spammish repetition')

before_all_user, before_all_sys = ticks_all()
before_process_user, before_process_sys = ticks_process()

threads = []
for i in xrange(0, 8):
  t = Thread(target=do_work)
  threads.append(t)
  t.start()
for t in threads:
  t.join()

after_process_user, after_process_sys = ticks_process()
after_all_user, after_all_sys = ticks_all()

print 'delta process: user:', after_process_user - before_process_user
+, 'sys:', after_process_sys - before_process_sys
print 'delta all: user:', after_all_user - before_all_user, 'sys:', af
+ter_all_sys - before_all_sys

[download]
Then my attempt at a perl approximation (I don't really know python, so if anyone sees anywhere I booboo'd, feel free to politely point it out ;-). 
#!/usr/bin/perl
use 5.16.0;
use threads;

sub open_for_read($) {
  open(my $handle, "<$_[0]") or die "opening $_[0]: $!";
  $handle }

sub ticks_all {
  my $f = open_for_read("/proc/stat");
  return (split ' ', <$f>)[1,3] }

sub ticks_process() {
  my $f = open_for_read("/proc/self/stat");
  return (split ' ', <$f>)[13,14] }

sub dowork () {
  use Digest::MD5;
  my $d = Digest::MD5->new;
  $d->add('nobody inspects');
  $d->add(' the spammish repetition') for (0 .. 10_000_000)} 

my ($before_all_user, $before_all_sys) = ticks_all();
my ($before_process_user, $before_process_sys) = ticks_process();

my @threads; 
for my $i (0 .. 8) {
  my $t = threads->create(\&dowork);
  push @threads,$t }
$_->join() foreach @threads;

my ($after_all_user, $after_all_sys) = ticks_all();
my ($after_process_user, $after_process_sys) = ticks_process();

#(note: changing perl defaults for print)
$, = " ";   #put spaces between output fields
$\ = "\n";  #add LF to end of lines by default

print 'delta process: user:', $after_process_user - $before_process_us
+er, 
      ' sys:', $after_process_sys - $before_process_sys;
print 'delta all: user:', $after_all_user - $before_all_user, 
      ' sys: ', $after_all_sys - $before_all_sys;

[download]
The results: 
> export TIMEFORMAT="%2Rsec %2Uusr %2Ssys (%P%% cpu)"

> time python ticks.py
delta process: user: 9263 sys: 2987
delta all: user: 6034 sys: 2178
67.35sec 92.64usr 29.89sys (181.94% cpu)

> time perl /tmp/pticks
delta process: user: 2917  sys: 3
delta all: user: 2926  sys:  25
3.36sec 29.20usr 0.03sys (870.05% cpu)
---

For 9 threads:

lang    #thrds  #coresuse  %efficency
python    9          1.82       20.2%
perl      9          8.70       96.7%

[download]
I tried to use as close to same semantics as the python program. Even used python indentation where practical (I did split the prints at the end... something python seems to have problems with...)

In reply to parallelism v.python by perl-diddler

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