Re: Benchmark for Scala, Ruby and Perl

On 2022-01-15 00:04, Jon Smart wrote:
> 
> Hello Paul
> 
> Do you mean by undef $/ and with <$fh> we can read the file into memory 
> at one time?

$/ is the input record separator, newline by default.
If undefined that means that the whole file is treated as one single record.


> Yes that would be faster b/c we don't need to read file by each line, 
> which increases the disk IO.
> 
> Another questions:
> 1. what's the "truss" command?

truss is a "unix" command.  Search for "truss unix".


> 2. what's the syntax "<:mmap"?

mmap enables a memory mapped file.  I treats the file as if it were a 
chunk of memory instead of a file.

Depending on the size of the file and the amount of memory available it 
may not make a difference.  Benchmark to confirm.


> On 15.01.2022 15:45, Paul Procacci wrote:
>>
>> -------------------------------------
>> use strict;
>>
>> $/ = undef;

That is usually written as:

local $/;

because $/ is a global variable and you want to limit the scope of any 
change.


>> my %stopwords = do {
>>         open my $fh, '<:mmap', 'stopwords.txt' or die $!;
>>         map { $_ => 1; } split /\n/, <$fh>;
>> };
>>
>> my %count = do {
>>         my %res;
>>         open my $fh, '<:mmap', 'words.txt' or die $!;
>>         map { $res{$_}++ unless $stopwords{$_}; } split /\n/, <$fh>;
>>         %res;
>> };
>>
>> my $i=0;
>> for (sort {$count{$b} <=> $count{$a}} keys %count) {
>>     if ($i < 20) {
>>         print "$_ -> $count{$_}\n"
>>     } else {
>>        last;
>>     }
>>     $i ++;
>> }



John

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