[Redis] Perl Redis Client news

[Steffen Mueller]

On 11/19/2013 04:51 PM, Pavel Shaydo wrote:
> On Mon Nov 18 18:20:29 2013
> melo at simplicidade.org (Pedro Melo) wrote:
>> RedisDB (I *think* its RedisDB…) has a XS interface. We could
>> compare it with our read()-based performance…
>
> It was some time ago, and I have no time right now to repeat
> benchmarks, but if I remember correctly RedisDB XS parser is about 30%
> faster than RedisDB PP parser.

Interesting!

I did a fairly naive[1] XS implementation of a parser and another fairly 
naive Perl implementation using non-consuming regexes (/\G.../gcs). On 
the simple response below, here's what I get:

my $reply = join "\r\n", qw(
   *3
   :123
   $-1
   $9
   hhhhhhhhh
), "";

use Benchmark qw(timethese);
timethese(-2, {
   xs => sub {my $x = xs_redis_parse($reply)},
   perl => sub {my $x = perl_redis_parse($reply)},
});

Benchmark: running perl, xs for at least 2 CPU seconds...

perl:  2 wallclock secs ( 2.05 usr +  0.00 sys =  2.05 CPU) @ 
125871.71/s (n=258037)

xs:  2 wallclock secs ( 2.10 usr +  0.00 sys =  2.10 CPU) @ 2184528.57/s 
(n=4587510)


So that's a factor of ~17x. :)

The XS implementation is here: 
https://github.com/tsee/smuellers_randomstuff/blob/master/redis-protocol-parser/XSFun.xs

The test and Perl implementation is here: 
https://github.com/tsee/smuellers_randomstuff/blob/master/redis-protocol-parser/t/redis.t

(Yes, it's a mess, but I checked it in to my "random stuff" repository 
for a reason.)

Now mind you, this is just for turning that response into a Perl array 
reference (or a string (status+error) or undef ("*-1")). It doesn't 
actually PROCESS what needs doing and it doesn't include reading from a 
stream. The latter would likely make a significant difference.

Best regards,
Steffen

[1] Naive here means that it's not fully validating. The C 
implementation should be safe to the point of "won't segfault" and 
"won't eat all your RAM", but it only traps a small number of error 
conditions as exceptions and otherwise relies on GIGO.