How are threads implemented in Python?

[Moshe Zadka]

On Sat, 27 Jan 2001 16:32:46 GMT, "Parzival Herzog" <parz at home.com> wrote:

> Are threads implemented as OS threads, thereby multi-threading the
> interpreter code, or does the Python interpreter itself maintain a
> list of Python treads and switch between them?

Well, both.
The threads are implemented as OS threads, but Python holds
a global interpreter lock (GIL), and only the thread that
holds the lock gets to run. The lock is released and reaquired
every N instructions.

Some instructions release the lock while waiting for OS activity:
the classical examples being reading from file descriptors or
sockets.
-- 
Moshe Zadka <sig at zadka.site.co.il>
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