An important topic related to both Ruby & Python is the Global Interpreter Lock (GIL). Because of GIL, pure Ruby/Python languages can use only one CPU (1 core) regardless of the available number of CPUS/Cores.
But GIL is a non-issue in at least three ways:
1> Common automatically eliminates GIL Language Runtime /Java Virtual Machine (CLR/JVM)
IronRuby/IronPython/JRuby/Jython/MacRuby have “no GIL” issues, because they map corresponding “green threads” to CLR threads or JVM threads or native threads.
2> Asynchronous Programming Approach
Even if using pure Ruby/Python, using a library like Twisted (for Python) or EventMachine (for Ruby) eliminates GIL/concurrency issues.
3> Using Separate Libraries