1. Overview of Ruby Enterprise Edition (REE)
Ruby Enterprise Edition (REE) is a server-oriented distribution of the official Ruby interpreter, and includes various additional enhancements:
A copy-on-write friendly garbage collector. Phusion Passenger uses this, in combination with a technique called preforking, to reduce Ruby on Rails applications' memory usage by 33% on average.
An improved memory allocator called tcmalloc, which improves performance quite a bit.
The ability to tweak garbage collector settings for maximum server performance.
The ability to inspect the garbage collector’s state and the object heap state, for debugging purposes.
The ability to obtain backtraces for all running threads, making it easier for one to debug multithreaded applications.
Thread scheduler bug fixes and performance improvements. Threading on Ruby Enterprise Edition can be more than 10 times faster than official Ruby 1.8.
Various memory management tweaks so that the Ruby interpreter uses less memory on average, even when copy-on-write is not utilized.
Some of these features are gathered from third party Ruby patches: RailsBench, Sylvain Joyeux’s object allocation patch, caller_for_all_threads, Darryl Gove’s and Miriam Blatt’s Sparc optimization patches, Joe Damato’s and Aman Gupta’s zero-copy context switching patch, Brent Roman’s MBARI patch set.