[Python-Dev] Software Transactional Memory for Python (original) (raw)

Armin Rigo arigo at tunes.org
Tue Aug 30 22:02:09 CEST 2011

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.

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