The number of threads is meant to be semi-tolerant to usage of blocking IO in go blocks. You can't be certain that some go block won't call a function that calls a function in some library that blocks for just a few milliseconds. So we tried to make it high enough to be tolerant of mis-use, but low enough to be bounded somewhat.
So yes, the number + 42 is arbitrary (and somewhat of a joke) but the fact that it's more than 2 * CPUs is intentional. Timothy On Thu, Feb 19, 2015 at 5:02 AM, Robin Heggelund Hansen < skinney...@gmail.com> wrote: > From the source of core.async, I see that it is started with a threadpool > of <number of processors>*2 + 42. > > I can understand the number of processors * 2 part, erlang does the same > thing. But Hitchicker's references aside, why add 42 to this? Won't that > many threads do more harm than good, in terms of overhead related to > context switching? > > -- > 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. > -- “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.
