unfolding info as seen when building a module depends on flags in a previously-compiled module
I've observed a blowup in ghc memory usage when invoked with parallel build flags.
to reproduce
cabal get xmlhtml-0.2.3.2
cabal install xmlhtml-0.2.3.2 --only-dependencies
cd xmlhtml-0.2.3.2 then
cabal clean ; cabal configure --ghc-options="-j4" ; time cabal build -j4 -v3will take quite a while and use > 1gb of ram
whereas
cabal clean ; cabal configure --ghc-options="-j1 ; time cabal build -j1 -v3
will use < 150mb of ram.
Based upon the output of cabal build -j4 -v3, it looks like the parallel build is spending a lottt more time in the simplifier passes. I'm not sure what changes between the parallel and sequential builds to change this. I'll try to dig into this more in a few days, but recording this problem now before i forget. (though of course any insights would be appreciated)
Trac metadata
| Trac field | Value |
|---|---|
| Version | 7.8.3 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |