You're doing all your computation in the generation of the lazy
sequence (which is in order). Then you're mapping "identity" in
parallel, but that doesn't do anything.
If you're willing to lose the "for" style bindings, try something more
like this:
(defmacro pdoseq
"Run over a sequence in parallel (like pmap)"
[seq-exprs & body]
(let [pairs (partition 2 seq-exprs)]
`(do (doall (pmap (fn ~(vec (map first pairs)) ~@body) ~@(map
second pairs))) nil)))
On Thu, May 24, 2012 at 3:56 PM, Cedric Greevey <cgree...@gmail.com> wrote:
> For some reason, this doesn't actually seem to be executing in parallel:
>
> (defmacro pdoseq
> "Bindings as for for, but parallel execution as per pmap, pcalls,
> pvalues; returns
> nil."
> [seq-exprs & body]
> `(do
> (doall
> (pmap identity
> (for ~seq-exprs (do ~@body)))
> nil)))
>
> user=> (pdoseq [i (range 10)] (println n))
> 0
> 1
> 2
> 3
> 4
> 5
> 6
> 7
> 8
> 9
>
> Never any interleaving of output and if I give it a big CPU-bound job
> to do for each integer it only saturates one core.
>
> I thought it might be a chunked-seq issue, but:
>
> user=> (chunked-seq? (range 10))
> false
>
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