> On 28 Nov 2017, at 02:54, Alex Miller <a...@puredanger.com> wrote: > > I would say transducers are preferable when: > > 1) you have reducible collections > 2) you have a lot of pipelined transformations (transducers handle these in > one pass with no intermediate data) > 3) the number of elements is "large" (this amplifies the memory and perf > savings from #2) > 4) you put to produce a concrete output collection (seqs need an extra step > to pour the seq into a collection; transducers can create it directly) > 5) you want a reusable transformation that can be used in multiple contexts > (reduction, sequence, core.async, etc)
I agree with the above Alex, although I think that is the kind of checklist I'd look at if performance optimizations is my primary goal. In any other case, I'd reach for transducers as the default. There are then several corner cases to understand, but that's true for normal sequential processing too. Renzo > > On Monday, November 27, 2017 at 8:33:50 PM UTC-6, Jiacai Liu wrote: > > Also, most of the performance boost from transducers is due to less garbage > > being created, and some times the heap of the JVM is so large you'll never > > see much change from switching to transducers. > > Thanks for this tip. I seldom use transducers in my daily work, and I was > convinced transducers are a better choice in whatever situation after reading > some articles. But the test shows it isn't an easy choice, only when do > something reducible, will transducers make more sense. > > On Tuesday, November 28, 2017 at 5:07:10 AM UTC+8, tbc++ wrote: > >> Also, I think the transducer version should always be faster, no matter > >> the size of the source collection (no threshold). > > It's a bit more complicated than that, mostly because transducer pipelines > require about 2 allocations per step during creation. Also, most of the > performance boost from transducers is due to less garbage being created, and > some times the heap of the JVM is so large you'll never see much change from > switching to transducers. > > Don't get me wrong, transducers are great and I often default to them over > seqs, but in micro-benchmarks like this there's too much in play to always > see a 100% performance boost. > > On Mon, Nov 27, 2017 at 12:55 PM, David Bürgin <dbue...@gluet.ch> wrote: > Jiacai – > > I saw you updated the gist. Just in case it passed you by: performance > profits from the source collection being reducible. So pouring ‘dataset’ > into a vector beforehand should speed up the processing quite a bit. > > Also, I think the transducer version should always be faster, no matter > the size of the source collection (no threshold). > > > -- > David > > -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clo...@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+u...@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+u...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > > > > -- > “One of the main causes of the fall of the Roman Empire was that–lacking > zero–they had no way to indicate successful termination of their C programs.” > (Robert Firth) > > -- > 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/d/optout. -- 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/d/optout.
