Very high memory usage

[tysonzero]

Memory usage for GHCJS is getting problematically large, specifically north of 30GB.

It seems like it may have gotten worse in our upgrade from 8.6 to 8.10 as well.

Is there a good way to find out why it's so high and reduce it?

[amesgen]

Seconding this. For Ormolu Live, I also had to disable the stack size limit (+RTS -K0) (otherwise the linking step would fail).

If one just wants to check that the code compiles via GHCJS, but not actually produce the JS (useful for CI), skipping the linking step via -no-code helps a lot (as this is where GHCJS uses enormous amounts of memory).

See here for our haskell.nix config: https://github.com/tweag/ormolu/blob/1eec90541c36f7a296352249a0ed147d3a1a6791/default.nix#L32_L33

[ddssff]

I'd like to point out pikajude/html-entity#2, which is a pull request for a change to a simple package that reduces the size of one ghcjs object file by about 99.8% (really) and fixes an out of memory error we were having. I'm using ghcjs-8.6.0.1, I'd be interested to hear the results for more recent compilers. Maybe this could point the way towards diagnosing this memory issue? It also reduces the size of the ghc object file by 95%.