Pre-emptive or co-operative concurrency (was: Concurrency)

Ross Paterson ross at
Wed Mar 29 06:24:35 EST 2006

On Wed, Mar 29, 2006 at 11:44:12AM +0100, Simon Marlow wrote:
> It's much more useful to reserve the term "cooperative" for
> when the burden is on the programmer to insert context-switch points, as
> is the case in Hugs.  This is a significant difference from the
> programmer's point of view, whereas the difference in imlementation
> between GHC and YHC is to a very close approximation invisible.

The dividing line isn't "cooperative", though.  Even if an implementation
did a context switch after each IO action (i.e. in >>=), it would fail
your first fairness requirement, as an IO action looping in pure code
will starve other threads (as does one that doesn't do allocation in GHC).

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