Hey all, just catching up on this thread after the weekend. Rich and I discussed the thread safety aspects of transducers last fall and the intention is that transducers are expected to only be used in a single thread at a time, but that thread can change throughout the life of the transducing process (for example when a go block is passed over threads in a pool in core.async). While transducing processes may provide locking to cover the visibility of state updates in a stateful transducer, transducers should still use stateful constructs that ensure visibility (by using volatile, atoms, etc).
The major transducing processes provided in core are transduce, into, sequence, eduction, and core.async. All but core.async are single-threaded. core.async channel transducers may occur on many threads due to interaction with the go processing threads, but never happen on more than one thread at a time. These operations are covered by the channel lock which should guarantee visibility. Transducers used within a go block (via something like transduce or into) occur eagerly and don't incur any switch in threads so just fall back to the same old expectations of single-threaded use and visibility. Note that there are a couple of stateful transducers that use ArrayList (partition-by and partition-all). From my last conversation with Rich, he said those should really be changed to protect themselves better with volatile or something else. I thought I wrote up a ticket for this but looks like maybe I didn't, so I will take care of that. Reducer fold is interesting in that each "bucket" is reduced via its reduce function, which can actually use a transducer (since that produces a reduce function), however, it can't be a stateful transducer (something like take, etc). Hope that helps with respect to intent. -- 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.
