Ideally, you wouldn't be using a side effect at all, but something like reducers to return a single computed result after going over the sequence. (If the input's too big for main memory, you'd also need to partition the input seq into reducible-collection chunks small enough to fit in memory.)
If side effects are necessary because you're doing I/O for each element of the seq, then the overhead of wrapping in pmap is probably minimal as the task is I/O-bound, but the benefit of pmap may not be significant either. Threaded I/O is generally only useful for 1. preventing I/O from bottlenecking a CPU-bound task by splitting them into separate threads and 2. networking with many remote hosts, so you can usefully do something with host B while waiting for a response from host A, or with one remote host where latency and task orthogonality make several parallel interactions preferable to several sequential ones (e.g. a web browser loading images several at a time from a web server when the throughput is high but so is the latency). If side effects are necessary because you're interacting with a legacy Java API that uses mutable state, you might want to look into pvalues and pcalls. On Wed, Oct 16, 2013 at 10:34 PM, Pradeep Gollakota <pradeep...@gmail.com>wrote: > Hi All, > > I’m (very) new to clojure (and loving it)… and I’m trying to wrap my head > around how to correctly choose doseq vs dorun for my particular use case. > I’ve read this earlier post > https://groups.google.com/forum/#!msg/clojure/8ebJsllH8UY/mXtixH3CRRsJand I > had a clarifying question. > > From what I gathered in the above post, it’s more efficient to use doseq > instead of dorun since map creates another seq. However, if the fn you want > to apply on the seq can be parallelized, doseq wouldn’t give you the > ability to parallelize. With dorun you can use pmap instead of map and get > parallelization. > > (doseq [i some-lazy-seq] side-effect-fn) > (dorun (pmap side-effect-fn some-lazy-seq)) > > What is the idiomatic way of parallelizing a computation on a lazy seq? > > Thanks, > Pradeep > > -- > -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clojure@googlegroups.com > Note that posts from new members are moderated - please be patient with > your first post. > To unsubscribe from this group, send email to > clojure+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/clojure?hl=en > --- > You received this message because you are subscribed to the Google Groups > "Clojure" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to clojure+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/groups/opt_out. > -- -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
