How to calculate elapsed time ?

[Stuart Clemons]

Hi all:

I'm trying to determine how long an system operation takes. Anyone know
of a simple way to do this ?

I wanted to establish the start time. Then run the operation. Then mark
the finish time. Then substract the start time from the finish time to
get an elapsed time. Here's the simplistic approach I tried. I'm sure I
need a time that is measured in seconds or something like that, but I'm
not sure how to do this.

TIA

Here's what I tried:

#!/usr/bin/perl -w
use warnings;
use strict;

my $start = "Tue Jan 27 15:40:16 2004";
print "This is the start time: $start \n";

system (This is where the system process stuff goes);

my $finish = localtime;
print "This is the finish time: $finish \n";

my $elapsedtime = ("$finish" - "$start") ;
print "This is the time diff: $elapsedtime \n";

The above obviously didn't work. Here's what it returned:

This is the start time: Tue Jan 27 15:40:16 2004
Argument "Tue Jan 27 15:40:16 2004" isn't numeric in subtraction (-) at
C:\Perl\timetest.pl line 13.
This is the finish time: Tue Jan 27 19:45:56 2004
This is the time diff: 0
Argument "Tue Jan 27 19:45:56 2004" isn't numeric in subtraction (-) at
C:\Perl\timetest.pl line ClearCase\Us

[James Edward Gray II]

On Jan 27, 2004, at 6:50 PM, [email]stuart_clemons@us.ibm.com[/email] wrote:

> Hi all:

Howdy.

> I'm trying to determine how long an system operation takes. Anyone
> know
> of a simple way to do this ?

You were on the right track. Try this:

my $start = time;

# do something to time here

my $time_taken = time - $start;

If you want more information on the time() subroutine, try (at the
commandline):

perldoc -f time

And if you get into timing things it won't be long before you want the
Benchmarking module, generally. You can read about it too:

perldoc Benchmark

Hope that helps.

James

[Randy W. Sims]

On 1/27/2004 7:50 PM, [email]stuart_clemons@us.ibm.com[/email] wrote:

> Hi all:
>
> I'm trying to determine how long an system operation takes. Anyone know
> of a simple way to do this ?
>
> I wanted to establish the start time. Then run the operation. Then mark
> the finish time. Then substract the start time from the finish time to
> get an elapsed time. Here's the simplistic approach I tried. I'm sure I
> need a time that is measured in seconds or something like that, but I'm
> not sure how to do this.

Use the Benchmark module or Time::Hires.

Randy.

[Toby Stuart]

> -----Original Message-----
> From: [email]stuart_clemons@us.ibm.com[/email] [mailto:stuart_clemons@us.ibm.com]
> Sent: Wednesday, January 28, 2004 11:51 AM
> To: [email]beginners@perl.org[/email]
> Subject: How to calculate elapsed time ?
>
>
> Hi all:
>
> I'm trying to determine how long an system operation takes.
> Anyone know
> of a simple way to do this ?
>
> I wanted to establish the start time. Then run the
> operation. Then mark
> the finish time. Then substract the start time from the
> finish time to
> get an elapsed time. Here's the simplistic approach I tried.
> I'm sure I
> need a time that is measured in seconds or something like
> that, but I'm
> not sure how to do this.
>
> TIA
>

[code snipped]

>

use Time::Elapse;

# somewhere in your program...
Time::Elapse->lapse(my $now);

#...rest of program execution

print "Time Wasted: $now\n";

[Wiggins D'Anconia]

[email]stuart_clemons@us.ibm.com[/email] wrote:

> Hi all:
>
> I'm trying to determine how long an system operation takes. Anyone know
> of a simple way to do this ?
>
> I wanted to establish the start time. Then run the operation. Then mark
> the finish time. Then substract the start time from the finish time to
> get an elapsed time. Here's the simplistic approach I tried. I'm sure I
> need a time that is measured in seconds or something like that, but I'm
> not sure how to do this.
>
> TIA
>
> Here's what I tried:
>
> #!/usr/bin/perl -w
> use warnings;
> use strict;
>
> my $start = "Tue Jan 27 15:40:16 2004";
> print "This is the start time: $start \n";
>
> system (This is where the system process stuff goes);
>
> my $finish = localtime;
> print "This is the finish time: $finish \n";
>
> my $elapsedtime = ("$finish" - "$start") ;
> print "This is the time diff: $elapsedtime \n";
>
> The above obviously didn't work. Here's what it returned:
>
> This is the start time: Tue Jan 27 15:40:16 2004
> Argument "Tue Jan 27 15:40:16 2004" isn't numeric in subtraction (-) at
> C:\Perl\timetest.pl line 13.
> This is the finish time: Tue Jan 27 19:45:56 2004
> This is the time diff: 0
> Argument "Tue Jan 27 19:45:56 2004" isn't numeric in subtraction (-) at
> C:\Perl\timetest.pl line ClearCase\Us

Assuming you don't need more granularity than seconds, you should just
use 'time'. Don't hardcode the start time either as this seems kind of
pointless, something like:

my $start = time;

system();

my $end = time;

Then subtract the two, that returns # of seconds. perldoc -f time

Depending on what your 'system' is doing you may need to look into
Time::HiRes to get partial second granularity.

[url]http://danconia.org[/url]

[John W. Krahn]

Stuart Clemons wrote:

>
> Hi all:

Hello,

> I'm trying to determine how long an system operation takes. Anyone know
> of a simple way to do this ?

Certainly. :-)

> I wanted to establish the start time. Then run the operation. Then mark
> the finish time. Then substract the start time from the finish time to
> get an elapsed time. Here's the simplistic approach I tried. I'm sure I
> need a time that is measured in seconds or something like that, but I'm
> not sure how to do this.

Hint:
perldoc -f time

> Here's what I tried:
>
> #!/usr/bin/perl -w
> use warnings;
> use strict;
>
> my $start = "Tue Jan 27 15:40:16 2004";
> print "This is the start time: $start \n";

my $start = time;
print 'This is the start time: ', scalar localtime $start, "\n";

> system (This is where the system process stuff goes);
>
> my $finish = localtime;
> print "This is the finish time: $finish \n";

my $finish = time;
print 'This is the finish time: ', scalar localtime $finish, "\n";

> my $elapsedtime = ("$finish" - "$start") ;
> print "This is the time diff: $elapsedtime \n";

my $elapsedtime = $finish - $start;
print "This is the time diff in seconds: $elapsedtime\n";


If you need microseconds instead of seconds look at the Time::HiRes
module.

perldoc Time::HiRes

Also have a look at the Benchmark module.

perldoc Benchmark



John
--
use Perl;
program
fulfillment

[Owen Cook]

On Tue, 27 Jan 2004 [email]stuart_clemons@us.ibm.com[/email] wrote:

> I'm trying to determine how long an system operation takes. Anyone know
> of a simple way to do this ?
>
> I wanted to establish the start time. Then run the operation. Then mark
> the finish time. Then substract the start time from the finish time to
> get an elapsed time. Here's the simplistic approach I tried. I'm sure I
> need a time that is measured in seconds or something like that, but I'm
> not sure how to do this.

You might want to look $^T variable.

This variable is the time (secs from 1970) that a perl program is started.



Owen

[James Edward Gray II]

On Jan 27, 2004, at 6:50 PM, [email]stuart_clemons@us.ibm.com[/email] wrote:

> Hi all:

Howdy.

> I'm trying to determine how long an system operation takes. Anyone
> know
> of a simple way to do this ?

You were on the right track. Try this:

my $start = time;

# do something to time here

my $time_taken = time - $start;

If you want more information on the time() subroutine, try (at the
commandline):

perldoc -f time

And if you get into timing things it won't be long before you want the
Benchmarking module, generally. You can read about it too:

perldoc Benchmark

Hope that helps.

James

[Stuart Clemons]

Thanks guys. You're the Best !

I used "time" instead of "localtime" and it's exactly what I need for now.
Perl is quickly becoming a very useful tool for me.

Thanks also for the doc info: perldoc -f time & perldoc Benchmark

- Stuart

Stuart Clemons/Westford/IBM wrote on 01/27/2004 07:50:30 PM:

>
> Hi all:
>
> I'm trying to determine how long an system operation takes. Anyone
> know of a simple way to do this ?
>
> I wanted to establish the start time. Then run the operation. Then
> mark the finish time. Then substract the start time from the
> finish time to get an elapsed time. Here's the simplistic approach
> I tried. I'm sure I need a time that is measured in seconds or
> something like that, but I'm not sure how to do this.
>
> TIA
>
> Here's what I tried:
>
> #!/usr/bin/perl -w
> use warnings;
> use strict;
>
> my $start = "Tue Jan 27 15:40:16 2004";
> print "This is the start time: $start \n";
>
> system (This is where the system process stuff goes);
>
> my $finish = localtime;
> print "This is the finish time: $finish \n";
>
> my $elapsedtime = ("$finish" - "$start") ;
> print "This is the time diff: $elapsedtime \n";
>
> The above obviously didn't work. Here's what it returned:
>
> This is the start time: Tue Jan 27 15:40:16 2004
> Argument "Tue Jan 27 15:40:16 2004" isn't numeric in subtraction (-)
> at C:\Perl\timetest.pl line 13.
> This is the finish time: Tue Jan 27 19:45:56 2004
> This is the time diff: 0
> Argument "Tue Jan 27 19:45:56 2004" isn't numeric in subtraction (-)
> at C:\Perl\timetest.pl line ClearCase\Us