RE: How can I keep track of the execution time of a script?

[Adam]

in reply to How can I keep track of the execution time of a script?

$^T is the time that the script started. So end your script by returning time()-$^T. You might want to put this in the sig die handler:

# your script goes here

BEGIN { $SIG{__DIE__} = sub { print + time() - $^T, $/, @_ } }
print + time() - $^T, $/

That prints the run time of your script in seconds.

Update: By the way, there is a module called Benchmark that is great for testing algorithms and routines and such. Turnstep wrote a great tutorial on it called Benchmarking Your Code

Update: For a variety of reasons, it is much better (and simpler too!) to use a single END block instead of the repition that I suggested. Thanks merlyn for pointing this out. (I also like the use of warn)

Also, If your script is taking longer then a minute or two, you might want to break down those seconds to be minutes:seconds, but don't forget the more work you do after that last call to time, the less accurate the stamp. (Well, time only has a granularity of a second... so you actually have plenty of room, but anyway...)

END { $a=time-$^T, warn sprintf "Runtime %d min %d sec\n", $a/60, $a%6
+0 }

[merlyn]

Perhaps you wanted an END block instead of a DIE handler.

END {
  warn "this script took ", time - $^T, " seconds\n";
}

A die handler is only triggered on aborts. END blocks are triggered on all normal terminations, including aborts.

-- Randal L. Schwartz, Perl hacker

[Adam]

Good call... I forgot about the END block.

[Sarcasmo]

Thanks. That works nicely. How can I get that in milliseconds?

[acid06]

If you're running this script in Windows you can use the Win32::GetTickCount to get the time in miliseconds I would do something like this:

BEGIN {
  $ms = Win32::GetTickCount();
}

END {
  warn 'This script took ',Win32::GetTickCount() - $ms,'miliseconds';
}

[Adam]

This has several flaws. First, the tick count is not milliseconds. Second, that count could roll in the middle of your execution, yeilding a negative run time. (this happens roughly once a month) Also, it's OS dependant.

I asked Sarcasmo what OS this was for, and the answer is Linux.

[Adam]

There is a module that can get you high resoltion time stamps: Time::HiRes

You should be able to take it from there.