Fine grained control of parallelism is a superb aspect of core.async. Cassandra is a distributed database, often a query requires you resolve-on-read denormalised data partitioned multiple ways (semantically, by time, etc). You can think of it like a grid I guess.
Lets say I have a query that I want to execute against Cassandra that covers a week of data, where the data is partitioned chronologically by the hour, and by modulo 24 to spread data around the cluster, that's going to require 4032 queries. Judicious use of core.async/pipeline-async allows me to execute those queries in parallel with granular control of the chronological / modulo parallelism independent of one another, meaning I can play with that parallelism in the REPL by just adjusting a couple of numbers and reviewing the results. Twiddling knobs, measuring output. That allows me to execute those 4032 queries in parallel, sub-second, with non-blocking requiring none of the overhead of thread-per-request. My services are Netty end-to-end (server and driver interface to Cassandra) so there are always a fixed number of threads. If I wanted to tune the buffers or thread-pool sizes I could probably get an even higher degree of throughput / lower-latency on each monolithic cassandra query, the constraints are known, quantifiable, and easily configurable. On Sunday, September 18, 2016 at 6:37:38 PM UTC+12, Matan Safriel wrote: > > Hi, > > It's very easy to see how core.async solves callback hell for front-end > development with clojurescript. > In what use cases would you use it for server-side? we already have > non-blocking IO from Java, and we have clojure agents. So what's a bunch of > salient use cases? > Are there prominent clojure http server implementations which rely on it > for transcending the threaded web service paradigm? > > Thanks, > Matan > > -- 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.
