Confused, are languages like python, ruby single threaded? unlike say java? (for web apps)
keeping this very short..
Python supports Multi Threading.
Python does NOT support parallel execution of its Threads.

Exception:
Above statement may vary with implementations of Python not using GIL (Global Interpreter Locking). 
If a particular implementation is not using GIL, then, that would be Multi Threaded as well as support Parallel Execution
I was reading how Clojure is 'cool' because of its syntax + it runs on the JVM so it is multithreaded etc. etc.
Are languages like ruby and python single threaded in nature then? (when running as a web app).
What are the underlying differences between python/ruby and say java running on tomcat?
Doesn't the web server have a pool of threads to work with in all cases?