Speeding Up ClojureScript Compilation
About
If you are using ClojureScript (and if not, why not? :-)) then I strongly recommend you enable parallel build.
I mistakenly thought this meant that it would run separate builds in parallel, but no, it is far cleverer and more useful than that, it builds a single build in parallel.
Also, to be crystal clear, this isn’t going to do anything to your runtime performance, only the build time._
Awesome sauce - speed me up!
It is as simple as adding it to your compiler
options in your cljsbuild
config:
:cljsbuild {:test-commands
;; Test command for running the unit tests in "test-cljs" (see below).
;; $ lein cljsbuild test
;; NOTE: this does not call health/bootstrap as that causes errors, hence cljs-dev and cljs-prod
{"unit" ["phantomjs"
"phantom/unit-test.js"
"resources/private/html/unit-test.html"]}
:builds
{:test {:source-paths ["src/clj" "src/clj-prod" "src/cljc" "src/cljs" "src/cljs-prod"]
:compiler {:parallel-build true
:output-to "resources/private/js/unit-test.js"
:output-dir "resources/private/js/out"
:optimizations :whitespace
:pretty-print true}}
:dev {:source-paths ["src/clj" "src/clj-prod" "src/cljc" "src/cljs" "src/cljs-prod"]
:figwheel {:on-jsload "health.bootstrap/run-render"
:websocket-host :js-client-host}
:compiler {:main health.core
:parallel-build true
:output-to "resources/public/compiled/js/app.js"
:output-dir "resources/public/compiled/js/out"
:asset-path "compiled/js/out"
:source-map-timestamp true}}
:prod {:source-paths ["src/clj" "src/clj-prod" "src/cljc" "src/cljs" "src/cljs-prod"]
:compiler {:main health.core
:parallel-build true
:output-to "resources/public/compiled/js/app.js"
:optimizations :advanced
;; for debugging
:pretty-print true
:pseudo-names true
;; for debugging
}}}}
I only added it to the
:dev
build but I guess you could add it to each build if you wanted to_
Anecdotally (meaning I can’t be bothered to time it properly) it sped up my build by about 300% - yep, that much. Restarting the REPL in the lovely CIDER is no longer an excuse to go and grab some coffee.
Have a great day!