[Haskell-cafe] Concurrency best practices?

[Evan Laforge]

On Sat, Feb 5, 2011 at 8:19 AM, Jesper Louis Andersen
<jesper.louis.andersen at gmail.com> wrote:
> On Sat, Feb 5, 2011 at 17:13, Andrew Coppin <andrewcoppin at btinternet.com> wrote:
>> On 05/02/2011 12:56 PM, Jesper Louis Andersen wrote:
>>
>> Presumably messages added to the channel appear immediately after the
>> transaction commits. The problem is, I think GHC's STM implementation might
>> mean that if two transactions both try to log a message, they both get
>> rolled back...
>>
>
> Yes, this is the performance caveat I was hinting at. When logging
> becomes heavy and transactions are *not* completing, you will have
> transaction retries due to the logging. If the transaction completes
> however, it is not that much of a problem.

I recall reading that clojure has a concept of associative
combination.  If you can declare that certain operations are
associative then the runtime doesn't have to care if they get out of
order.