[Python-Dev] Software Transactional Memory for Python

[Armin Rigo]

Re-hi,

2011/8/29 Armin Rigo <arigo at tunes.org>:
>> The problem is that many locks are actually acquired implicitely.
>> For example, `print` to a buffered stream will acquire the fileobject's mutex.
>
> Indeed.
> (...)
> I suspect that I need to do a more thorough review of the stdlib (...)

I found a solution not involving any change in CPython, and updated
the patch.  The solution is to say that a "with atomic" block doesn't
completely prevent other threads from re-acquiring the GIL, but only
prevents them from proceeding to the following bytecode.  So if
another thread is currently suspended in a place that releases the GIL
for other reasons, then this other thread can still be switched to as
normal, and continue running until the end of the current bytecode.  I
think it's sane enough for the original purpose, and avoids most
deadlock cases.


A bientôt,

Armin.