# -*- rdoc -*- = NEWS for Ruby 2.1.0 This document is a list of user visible feature changes made between releases except for bug fixes. Note that each entry is kept so brief that no reason behind or reference information is supplied with. For a full list of changes with all sufficient information, see the ChangeLog file. == Changes since the 2.0.0 release === Language changes === Core classes updates (outstanding ones only) * GC * added environment variable: * RUBY_HEAP_SLOTS_GROWTH_FACTOR: growth rate of the heap. * Mutex * misc * Mutex#owned? is no longer experimental. === Core classes compatibility issues (excluding feature bug fixes) * Module#ancestors The ancestors of a singleton class now include that singleton class. === Stdlib updates (outstanding ones only) * Net::SMTP * Added Net::SMTP#rset to implement the RSET comamnd * Rinda::RingServer, Rinda::RingFinger * Rinda now supports multicast sockets. See Rinda::RingServer and Rinda::RingFinger for details. === Stdlib compatibility issues (excluding feature bug fixes) === C API updates