+++ /dev/null
-Somewhere along the line, I learned about a way to slurp files faster
-than by setting $/ to undef. The method is very simple, you do a single
-read call with the size of the file (which the -s operator provides).
-This bypasses the I/O loop inside perl that checks for EOF and does all
-sorts of processing. I then decided to experiment and found that
-sysread is even faster as you would expect. sysread bypasses all of
-Perl's stdio and reads the file from the kernel buffers directly into a
-Perl scalar. This is why the slurp code in File::Slurp uses
-sysopen/sysread/syswrite. All the rest of the code is just to support
-the various options and data passing techniques.
-
-
-Benchmarks can be enlightening, informative, frustrating and
-deceiving. It would make no sense to create a new and more complex slurp
-module unless it also gained signifigantly in speed. So I created a
-benchmark script which compares various slurp methods with differing
-file sizes and calling contexts. This script can be run from the main
-directory of the tarball like this:
-
- perl -Ilib extras/slurp_bench.pl
-
-If you pass in an argument on the command line, it will be passed to
-timethese() and it will control the duration. It defaults to -2 which
-makes each benchmark run to at least 2 seconds of cpu time.
-
-The following numbers are from a run I did on my 300Mhz sparc. You will
-most likely get much faster counts on your boxes but the relative speeds
-shouldn't change by much. If you see major differences on your
-benchmarks, please send me the results and your Perl and OS
-versions. Also you can play with the benchmark script and add more slurp
-variations or data files.
-
-The rest of this section will be discussing the results of the
-benchmarks. You can refer to extras/slurp_bench.pl to see the code for
-the individual benchmarks. If the benchmark name starts with cpan_, it
-is either from Slurp.pm or File::Slurp.pm. Those starting with new_ are
-from the new File::Slurp.pm. Those that start with file_contents_ are
-from a client's code base. The rest are variations I created to
-highlight certain aspects of the benchmarks.
-
-The short and long file data is made like this:
-
- my @lines = ( 'abc' x 30 . "\n") x 100 ;
- my $text = join( '', @lines ) ;
-
- @lines = ( 'abc' x 40 . "\n") x 1000 ;
- $text = join( '', @lines ) ;
-
-So the short file is 9,100 bytes and the long file is 121,000
-bytes.
-
-=head3 Scalar Slurp of Short File
-
- file_contents 651/s
- file_contents_no_OO 828/s
- cpan_read_file 1866/s
- cpan_slurp 1934/s
- read_file 2079/s
- new 2270/s
- new_buf_ref 2403/s
- new_scalar_ref 2415/s
- sysread_file 2572/s
-
-=head3 Scalar Slurp of Long File
-
- file_contents_no_OO 82.9/s
- file_contents 85.4/s
- cpan_read_file 250/s
- cpan_slurp 257/s
- read_file 323/s
- new 468/s
- sysread_file 489/s
- new_scalar_ref 766/s
- new_buf_ref 767/s
-
-The primary inference you get from looking at the mumbers above is that
-when slurping a file into a scalar, the longer the file, the more time
-you save by returning the result via a scalar reference. The time for
-the extra buffer copy can add up. The new module came out on top overall
-except for the very simple sysread_file entry which was added to
-highlight the overhead of the more flexible new module which isn't that
-much. The file_contents entries are always the worst since they do a
-list slurp and then a join, which is a classic newbie and cargo culted
-style which is extremely slow. Also the OO code in file_contents slows
-it down even more (I added the file_contents_no_OO entry to show this).
-The two CPAN modules are decent with small files but they are laggards
-compared to the new module when the file gets much larger.
-
-=head3 List Slurp of Short File
-
- cpan_read_file 589/s
- cpan_slurp_to_array 620/s
- read_file 824/s
- new_array_ref 824/s
- sysread_file 828/s
- new 829/s
- new_in_anon_array 833/s
- cpan_slurp_to_array_ref 836/s
-
-=head3 List Slurp of Long File
-
- cpan_read_file 62.4/s
- cpan_slurp_to_array 62.7/s
- read_file 92.9/s
- sysread_file 94.8/s
- new_array_ref 95.5/s
- new 96.2/s
- cpan_slurp_to_array_ref 96.3/s
- new_in_anon_array 97.2/s
-
-
-=head3 Scalar Spew of Short File
-
- cpan_write_file 1035/s
- print_file 1055/s
- syswrite_file 1135/s
- new 1519/s
- print_join_file 1766/s
- new_ref 1900/s
- syswrite_file2 2138/s
-
-=head3 Scalar Spew of Long File
-
- cpan_write_file 164/s 20
- print_file 211/s 26
- syswrite_file 236/s 25
- print_join_file 277/s 2
- new 295/s 2
- syswrite_file2 428/s 25
- new_ref 608/s 2
-
-
-=head3 List Spew of Short File
-
- cpan_write_file 794/s
- syswrite_file 1000/s
- print_file 1013/s
- new 1399/s
- print_join_file 1557/s
-
-=head3 List Spew of Long File
-
- cpan_write_file 112/s 12
- print_file 179/s 21
- syswrite_file 181/s 19
- print_join_file 205/s 2
- new 228/s 2
-
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