[Raymond Hettinger]
>> FWIW, the new with-statement makes the above fragment even more
>> readable:
>>
>> with atomic_transaction():
>> # do a series of steps without interruption
[Phillip J. Eby]
> +1 on the idea, -1000 on the name. It's neither atomic nor a
> transaction. I believe that "critical section" is a more common term for
> what you're proposing.
No, there is no common term for this idea, no "standard" threading
model supports it directly (which is bad news for portability, of
course), and it's a Bad Idea to start calling it "critical section"
here.
There _is_ some variation in what "critical section" means, exactly,
to different thread programming cultures, but in none does it mean:
a section of code such that, once a thread enters it, all other
threads are blocked from doing anything for the duration
The common meaning is:
a section of code such that, once a thread enters it, all other
threads are blocked from entering the section for the duration
which is a very far cry from getting blocked from doing anything.
In some thread cultures, "critical section" also implies that a thread
won't migrate across processors (on a multi-CPU box) while that thread
is in a critical section, and that's in addition to the "other threads
are blocked from entering the section for the duration" meaning.
In some thread cultures, "critical section" isn't distinguished from
the obvious implementation in terms of acquiring and releasing a mutex
around the code section, but that gets muddy. For example, on Win32
using a native mutex actually implments a cross-*process* "critical
section", while the term "critical section" is reserved for
cross-thread-within-a-process but not-cross-process mutual exclusion.
_______________________________________________
Python-Dev mailing list
Python-Dev@python.org
http://mail.python.org/mailman/listinfo/python-dev
Unsubscribe:
http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
