python philosophical question - strong vs duck typing

Robert Kern robert.kern at
Mon Jan 9 05:45:00 EST 2012

On 1/9/12 5:35 AM, John Nagle wrote:

> Python has some serious problems that preclude optimization.
> Basically, the language is designed to be run by a naive (non-optimizing)
> interpreter, and allows things that are easy
> for such an implementation but very tough to optimize. An
> example is the ability to store into the variables of a module
> from outside it, and even from another thread. Every attempt
> to get rid of the Global Interpreter Lock has hit that problem.

You keep repeating this falsehood about the GIL. You have been repeatedly shown 
that this is false[1][2], though I have yet to see you acknowledge it. The GIL 
exists to protect Python's internal data structures, mostly the reference counts 
on objects. The reason that the attempts to remove the GIL from CPython have not 
been accepted is because they cause unacceptable performance losses in the 
common unthreaded case. In implementations of Python that do not use reference 
counting, there is no GIL. Neither Jython nor IronPython have a GIL, but they 
both have the standard Python semantics that let you store variables into 
modules from the outside, even from other threads.


Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco

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