[Haskell-cafe] Software Transactional Memory and LWN

[Luke Palmer]

On Thu, Jun 11, 2009 at 2:30 AM, Ketil Malde <ketil at malde.org> wrote:

>
> Hi,
>
> Browsing LWN, I ran across this comment:
>
> http://lwn.net/Articles/336039/
>
> The author makes a bunch of unsubstantiated claims about STM, namely
> that all implementations use locking under the hood, and that STM can
> live- and deadlock.  I've seen a lot of similar sentiments in other
> places as well (comp.arch springs to mind).
>
> Now, I'm no expert on STM, but I was pretty sure these are incorrect,
> and I certainly had the impression that Haskell's STM guarantees some
> progress - which it couldn't in a deadlock situation.


MVars can be simulated with STM, and MVars can semantically get in a
deadlock situation, so STM can also deadlock.

Admittedly, if you're using STM to simulate MVars, you're doing it wrong.

Luke
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