Phusion has published a new release of their Ruby Enterprise Edition in version 1.8.7-20090928. Previous releases have all based on Ruby 1.8.6, this one now has Ruby 1.8.7 as its origin. Ruby 1.8.7 has been available quite some time now, why switching just now? Phusion addresses this question in their release announcement:
We were initially reluctant about switching to 1.8.7: many people reported various incompatibility problems introduced by 1.8.7, and it seemed that alternative Ruby implementers were boycotting 1.8.7. However, the tide has now changed. Rails 3.0 will drop support for Ruby versions earlier than 1.8.7, JRuby had recently decided to support 1.8.7 and OS X Snow Leopard as well as all the Linux distros ship 1.8.7. We've received a lot of requests from the community for a 1.8.7-based version.
Other news in this release includes the integration of Brent Roman's MBARI patches that improve performance and lowers memory usage. To boost multithreaded speed, a patch from Joe Damato and Aman Gupta has been included as an optional and experimental feature.
How much improvement do these patches achieve? This Ruby Enterprise Edition release has been tested with Twitter, where it led to significant improvements in throughput, as Evan Weaver reported. Evan also noticed that "Ruby is faster if compiled with -Os (optimize for size) than with -O2 or -O3 (optimize for speed). [Phusion's] Hongli pointed out that Ruby has poor instruction locality and benefits most from squeezing tightly into the instruction cache".
InfoQ asked the team behind Ruby Enterprise Edition if there are problems upgrading to the new versions. Ninh Bui from Phusion answers:
Well, apart from the compatibility problems from 1.8.6 to 1.8.7, tcmalloc – the memory allocator we use – doesn't seem to work yet on snow leopard.
Ninh's colleague Hongli Lai notes:
There are some issues with Xen support: REE is reported to print various (harmless) warning messages when run in Xen. We plan on fixing this in future releases with Xen-specific compilation flags. As for incompatibilities between 1.8.6 and 1.8.7, they're caused by semantic changes, e.g. some methods now return Enumerable instead of Array, some standard libraries classes changed in subtle ways, etc.
The community has caught on with these changes so I don't expect any incompatibility problems.