On Tue, 28 Apr 2020, Ben Franksen wrote:
Today I ran again into a problem I had several times before: compiling Cabal-3.2.* (the library) with ghc-8.2.2 and cabal with default options (including jobs: $ncpu, though it actually used only one cpu) eats all the memory on my machine (8GB, but I had a tor browser and another browser and thunderbird running) so that it completely freezes (no mouse, no keyboard). Had to reboot using sysrq escape hatch. Not funny. I think this is due to use of ghc --make and some very large modules. Thankfully memory use has improved with later ghc versions.
That's why I never use 'jobs: $ncpu' and also oppose to use this as the default setting. [1] There are some modules in packages that frequently eat up all my resources, e.g. I know that building "Cabal the library" is such a package. I remember that I can save memory by aborting compilation and restart it. It seems that GHC may cache too much. But continuing an aborted compilation is not possible for imported packages when using 'cabal install'. Other packages contain big modules automatically created by Template Haskell. [1] https://github.com/haskell/cabal/issues/5776