Ruby 2.1 has been released on Christmas day and is billed as offering “speedup without severe incompatibilities”. The performance boost is down to a new method cache in the VM and a new generational garbage collection system. The old method cache was cleared eacg time a new method was defined but now only that cache damage has been tracked down and reduced and a future of a more optimal larger cache has been opened up.
The generational GC was added as part of an optimisation of Ruby’s object management which also adds hooks for allocation and deallocation – there’s a deeper look into these changes in Koichi Sasada’s presentation(PDF) from RubyConf 2013. The GNU Multiple Precision Arithmetic Library is also now used to accelerate Bignum calculations.
Beyond the runtime changes, there are some language changes such as a new method for Array – to_h – to turn key/value pairs into a hash, a new syntax for rational numbers so that 1//2 is the same as Rational(1,2) and the addition of an explaining cause to Exceptions, but they seem to be few and far between. A full list is in the NEWS file which also notes any compatibility issues. Source for Ruby 2.1 is available now for download and will most probably be appearing in various binary forms over the coming weeks.
The performance improvements, although useful, will not help the perception that, outside of the CRUD web applications where Ruby and Rails made their mark, the native form of the language benchmarks as one of the slower languages out there. They will at least though help Ruby when it comes to a developer deciding which tradeoffs they want to make.