Brad Clow wrote:
On Nov 28, 2007 11:30 AM, Matthew Brecknell <[EMAIL PROTECTED]> wrote:
Even with threads, results are evaluated only when they are needed (or
when forced by a strictness annotation). So the thread that needs a
result (or forces it) first will be the one to evaluate it.
So does GHC implement some sychronisation given that a mutation is
occuring under the covers, ie. the thunk is being replaced by the
result?
Yes, see
http://haskell.org/~simonmar/bib/multiproc05_abstract.html
we use lock-free synchronisation, with a slight possibility that two
threads might evaluate the same thunk. But since they'll produce the same
result, nothing goes wrong.
Cheers,
Simon
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