[Parseperl-discuss] PPI::XS: Good candidates for XS implementation?

[Torsten S. <kaf...@gm...>]

Aloha,

since I have quite a bit of XS experience, I thought I'd tackle
implementing a few methods in PPI::XS to speed things up.  To find
bottlenecks I used the module I talked about in the earlier message and
let it analyze a ~3500 line program under the supervision of a
profiler.[1]  The profiles unveiled a few hotspots:

* PPI::Node::find_first, 9 calls, ~9 seconds
* PPI::Tokenizer::_process_next_char, 44305 calls, ~3.5 seconds
* PPI::Lexer::_lex_statement, 2908 calls, ~3 seconds

PPI::Node::find_first calls many methods and does little computation on
its own, so implementing it in XS wouldn't provide much benefit.  The
same is true for PPI::Lexer::_lex_statement.
PPI::Tokenizer::_process_next_char looked more promising.  So I wrote an
XS port of it.  Patch attached.

Well, the bad news is that this didn't improve performance measurably.

I looked at a few other candidates in the profiles but the all seem to
have the same issue: not much computation, lots of method calls.  I
don't think you can improve code like this very much by simply porting
it to XS verbatim.  perl already does a pretty good job when it creates
the optree, it seems.

So, any suggestions on what might be a good candidate for porting?

-- 
Bye,
-Torsten

[1] I tried Devel::DProf, Devel::Profile, and Devel::AutoProfiler.  All
yielded similar results.