How to reduce Elma compilation time on Circle CI or Travis CI?

Question

Compilation

elm is very slow on ci (circle / travis). I personally suffer from> 30 m of build time in a circle for a rather small elm project. https://github.com/elm-lang/elm-compiler/issues/1473 suggests "determining the number of processors is a problem" and recommends using libsysconfcpus to return 1 CPU instead of the actual detected amount. Is there any other way to mitigate this long compilation time?

Answer 1

From https://elmlang.slack.com/archives/general/p1484149451013255

@rtfeldman:

There is a known speed problem with the circle and Travis, because they incorrectly report the number of processors, but there is a workaround: add the equivalent of their configuration to your environment:

• https://github.com/elm-community/elm-test/blob/master/.travis.yml#L6
• https://github.com/elm-community/elm-test/blob/master/.travis.yml#L22-L30
• https://github.com/elm-community/elm-test/blob/master/.travis.yml#L39-L41 (Rev)

they basically change elm-make to a script that runs elm-make with sysconfcpus -n 2 so that elm-make know the actual number of available CPUs

I talked with people about this, and tl; dr is that they are not interested in fixing it, but may gain a foothold in the future release of some of the materials that they use

Answer 2

Consider the setup:

 sudo: true 

at .travis.yml . He cut the Haskell assembly from 18 minutes to 3.

Answer 3

for users who are looking for a quick and dirty fix: using libsysconfcpus to limit the amount detected by sysconf really reduces the knitting time by an order of magnitude around ci.