Python threads: backed by OS threads?

[Andrew Maizels]

Courageous wrote:

> I just read that. It suggests that the threads may
> be mutually locking eachother out some of the time,
> but it does not say that they will not see a performance
> gain once you discount the contention issues.
> 
> In particular, the brief discussion might suggest to
> this otherwise naive reader that if the threads were
> operating in relative mutual exclusion to eachother and
> objects which, once divided between them, were non-
> co-referencial, here might not be as much contention
> for python locking structures as the document mentions.

Unfortunately, the locking mechanism is very simple: it doesn't know
whether you're going to run into trouble or not, so it always acquires
the lock so that only one thread of Python code can run at any time.

However, I/O operations can effectively multithread, so if you're doing
a lot of I/O, you may see a performance improvement.  One of my programs
ran up to 80% faster when moved from a single-processor to a
dual-processor machine.

Andrew.
-- 
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