From: Charles Oliver Nutter <charles.nutter@...>
Date: 2009-03-18T12:18:15+09:00
Subject: Re: BigNum optimizations

M. Edward (Ed) Borasky wrote:
> Ezra ... is this something Engine Yard could do for 1.8.6 / Rubinius?
> I think the jRuby people are working on their Bignum performance too.

We're mostly just wrapping the JDK's builtin BigInteger class, which is 
not known for its scorching performance. BigInteger.doubleValue actually 
passes the number through a a String and re-parses it (a contributor 
implemented a replacement, for obvious reasons). There are alternative 
libraries, but we have not merged them in to avoid bloating the size of 
JRuby's distribution.

Of course almost all of them can be called directly through our Java 
integration layer, so if people need the performance they can do that. 
Java 7 is supposed to include a number of performance improvements for 
BigInteger as well.

We would not decline a clean-room implementation of Bignum that uses the 
latest and greatest algorithms :) It would probably be easier in Java 
than in C.

- Charlie