4 ms·

On my 4-core i7 Macbook Pro: time ./startup_time.pl 0.016s time ./startup_time.py 0.295s Parsing a 20Mb log file with a regex: time ./parse_log

• orf 6y ago
  Lets see the code? Regex has always been a Perl selling point, and you're just benchmarking the Python Regex library (written in C) against Perl's regex library. That's not a fantastic basis for a comparison.
  • cutler 6y ago
    Perl 5: #!/usr/bin/env perl use 5.026; open my $fh, '<', 'logs1.txt'; while (<$fh>) { chomp; say if /\b\w{15}\b/; } close $fh; Python 3.8 #!/usr/bin/env python import re with open('logs1.txt', 'r') as fh: for line in fh: if re.search(r'\b\w{15}\b', line): print(line, end='') Why isn't it a fair comparison? The startup time is generic and string parsing is a major feature of, say, web development. I didn't say Perl5 numerics match Python's but even there Python relies on external libs.
    • dgfitz 6y ago
      The python code should run much faster if you don't print.. Edit: perl is still faster, to be clear
      • cutler 6y ago
        That's like saying they're both as fast if you amputate one of Perl's legs.
    • tomku 6y ago
      It doesn't account for anywhere near the whole difference, but in a tight loop like that Python's going to be spending a good chunk of its time re-compiling the regex from the raw string literal every iteration. Hoist the regex definition out of the loop like so and it'll probably run about 30% faster: #!/usr/bin/env python3 import re with open('logs1.txt', 'r') as fh: regex = re.compile(r'\b\w{15}\b') for line in fh: if regex.search(line): print(line, end='') Perl almost certainly does this by default for regex literals, and that's a fair advantage for the "kitchen sink" style of language design versus orthogonal features (regex library, raw strings) that Python uses.
      • orf 6y ago
        Python caches patterns, you almost never need to re.compile unless you’re a library or have a specific use case involving lots of unique patterns. The issue here is that pythons regex engine has overhead, and with lots of sequential calls with small strings like that the overhead adds up. If you batch lines together in chunks you’ll see a huge improvement in speed, but the point is that it’s not “Python vs Perl” it’s “pythons regex engine vs Perl’s regex engine”. Which is about a contrived Perl-biased benchmark if ever there was one.
      • cutler 6y ago
        With pre-compiled regex the Python version comes down to 1.483s on my machine which is still considerably slower than Perl. I wrote versions of these using substring `index` instead of a regex and Perl was still the clear winner: time ./index.pl 0.258s time ./index.py 0.609s If you factor-in that Python startup time is 0.279s slower than Perl the processing differential comes down to 0.072s.
        • dgfitz 6y ago
          I'd be curious on your take of my code below, I have python and perl as dead even if you don't print and ignore pythons startup time.
          • cutler 6y ago
            Well, the two ifs you hedge to qualify Python's parity are pretty damning in themselves, no? Let's stop beating about the bush - if you want to perform a common text-processing job like parsing a log file Perl is hands down faster than Python.
    • dgfitz 6y ago
      Running a different test the slowest part of the python script is the startup time, otherwise they're identical: [admin@localhost ~]$ time ./test.py real 0m0.295s user 0m0.158s sys 0m0.138s [admin@localhost ~]$ time ./test.pl real 0m0.164s user 0m0.158s sys 0m0.006s #!/usr/bin/env perl use 5.16.3; open my $fh, '<', 'logs1.txt'; while (<$fh>) { chomp; if (/\b\w{15}\b/) {} } close $fh; #!/usr/bin/env python import re regex = re.compile(r'\b\w{15}\b') with open('logs1.txt', 'r') as fh: for line in fh: if regex.search(line): continue
  • mappu 6y ago
    I took some similar benchmarks recently: https://code.ivysaur.me/interpreter-binary-perf https://code.ivysaur.me/interpreter-binary-perf Perl5 won the dec2bin benchmark. The other thing I learned was that PHP's binary/decimal functions are two orders of magnitude slower, despite its core interpreter performance being best-in-class.
    • cutler 6y ago
      On the other hand PHP has a PCRE jit option which manages to beat even Perl's regex implementation.
      • rurban 6y ago
        Yes but you can use that jit also with perl5. https://metacpan.org/pod/re::engine::PCRE2 https://metacpan.org/pod/re::engine::PCRE2 It has even less backcompat problems than the native regex.
• smabie 6y ago
  https://benchmarksgame-team.pages.debian.net/benchmarksgame/fastest/perl-python3.html https://benchmarksgame-team.pages.debian.net/benchmarksgame/...