[dragonwriter]

> If you need multithreading (not multiprocessing), you cannot use Python.

If you need multithreading of Python code for parallelism, you cannot use CPython (and, consequently, can't use Python 3.)

Both IronPython and Jython use native threads without a GIL.

[kintamanimatt]

The GIL only restricts utilization of multiple cores. This makes parallelism harder but not concurrency. Python fully supports threads, but you won't find two threads in the same process running at the same time.

[falcolas]

Small clarification - you will if they are down in C code. i.e. you can have multiple threads in Python blocking on IO just fine. Or three threads concurrently running C code which releases the GIL until it needs to be re-acquired. Quite a few standard libraries which require significant processing power do exactly this.

[khyryk]

I think you're right, but on a related topic, I've yet to find something that works as easily as Go's select statement in Python.