Extract a local
Lazy initialization is no longer necessary here
Extend tests that hang on 64-bit Linux
Rename ivars
Set abort_on_exception everywhere
Don't install redcarpet on JRuby
Use https://rubygems.org
Need to handle IOError for JRuby
Use base exception class here
Cosmetics
Flush writes for non-performance critical operations

Fixes concurrent channel operations eon JRuby
n times is enough
Lower n to 50