sobering observation, python vs. perl

[srinivas devaki]

please upload the log file,

and global variables in python are slow, so just keep all that in a
function and try again. generally i get 20-30% time improvement by
doin that.


On Thu, Mar 17, 2016 at 8:59 PM, Charles T. Smith
<cts.private.yahoo at gmail.com> wrote:
> I've really learned to love working with python, but it's too soon
> to pack perl away.  I was amazed at how long a simple file search took
> so I ran some statistics:
>
>     $ time python find-rel.py
>     ./find-relreq *.out | sort -u
>     TestCase_F_00_P
>     TestCase_F_00_S
>     TestCase_F_01_S
>     TestCase_F_02_M
>
>     real    1m4.581s
>     user    1m4.412s
>     sys     0m0.140s
>
>
>     $ time python find-rel.py
>     # modified to use precompiled REs:
>     TestCase_F_00_P
>     TestCase_F_00_S
>     TestCase_F_01_S
>     TestCase_F_02_M
>
>     real    0m29.337s
>     user    0m29.174s
>     sys     0m0.100s
>
>
>     $ time perl find-rel.pl
>     find-relreq.pl *.out | sort -u
>     TestCase_F_00_P
>     TestCase_F_00_S
>     TestCase_F_01_S
>     TestCase_F_02_M
>
>     real    0m5.009s
>     user    0m4.932s
>     sys     0m0.072s
>
> Here's the programs:
>
> #!/usr/bin/env python
> # vim: tw=0
> import sys
> import re
>
> isready = re.compile ("(.*) is ready")
> relreq = re.compile (".*release_req")
> for fn in sys.argv[1:]:                                 # logfile name
>     tn = None
>     with open (fn) as fd:
>         for line in fd:
>             #match = re.match ("(.*) is ready", line)
>             match = isready.match (line)
>             if match:
>                 tn = match.group(1)
>             #match = re.match (".*release_req", line)
>             match = relreq.match (line)
>             if match:
>                 #print "%s: %s" % (tn, line),
>                 print tn
>
> vs.
>
> while (<>) {
>     if (/(.*) is ready/) {
>         $tn = $1;
>     }
>     elsif (/release_req/) {
>         print "$tn\n";
>     }
> }
>
> Look at those numbers:
> 1 minute for python without precompiled REs
> 1/2 minute with precompiled REs
> 5 seconds with perl.
> --
> https://mail.python.org/mailman/listinfo/python-list



-- 
Regards
Srinivas Devaki
Junior (3rd yr) student at Indian School of Mines,(IIT Dhanbad)
Computer Science and Engineering Department
ph: +91 9491 383 249
telegram_id: @eightnoteight