Configuring now always takes an insane amount of memory

[leftaroundabout]

After installing the HEAD version of Cabal (8315dbf), it has become practically unusable because any configure (or new-configure) allocates about 11 GiB of memory, which is quite enough to drive my laptop hopelessly into swap.

cabal-install apparently does this before even doing any of the actual configuration work, because when there's a syntax error in the .cabal file, I only get an error after the memory load is down again.

I thought it might have something to do with old cruft in my ~/.cabal, but even completely removing that and setting up from scratch didn't change anything. Nor did it help to remove everything in /tmp.

System info: Ubuntu 16.04, ghc-8.3.20170622.

[23Skidoo]

This doesn't affect 2.0, right?

[23Skidoo]

I wonder why Travis didn't catch this. Can this have something to do with the fact that you're using GHC HEAD?

[23Skidoo]

@leftaroundabout Does this happen with all packages or only with your project? Can you post repro instructions?

[leftaroundabout]

The issue happens with all packages (even a module Main where main = return () dummy).

Same problem with a cabal-install-2.0.0.0 I've just built (using that same GHC-HEAD compiler), so it looks a lot like it has something to do with either GHC-HEAD or my local configuration. Will try compiling cabal-install with another compiler now...

[leftaroundabout]

Ok, when cabal-install is built with ghc-8.0.1, the problem is gone.

[21:24:19]sagemuej@sagemuej-X302LA:/tmp/cbt  # a basically empty dummy package
$ /home/sagemuej/local/progwrit/haskell/notmine/haskell/cabal/.stack-work/install/x86_64-linux/ghc-8.0.1/8.0.1/bin/cabal configure -v3
no user package environment file found at /tmp/cbt
Searching for ghc in path.
Found ghc at /usr/local/bin/ghc
/usr/local/bin/ghc --numeric-version
/usr/local/bin/ghc is version 8.3.20170622
looking for tool ghc-pkg near compiler in /usr/local/bin
candidate locations:
["/usr/local/bin/ghc-pkg","/usr/local/bin/ghc-pkg-ghc-8.3.20170622","/usr/local/bin/ghc-pkg-8.3.20170622","/usr/local/bin/ghc-pkg"]
found ghc-pkg in /usr/local/bin/ghc-pkg
/usr/local/bin/ghc-pkg --version
/usr/local/bin/ghc-pkg is version 8.3.20170622
/usr/local/bin/ghc --supported-languages
/usr/local/bin/ghc --info
creating dist
Reading installed packages...
/usr/local/bin/ghc-pkg dump --global -v0
/usr/local/bin/ghc-pkg dump --user -v0
/usr/local/bin/ghc --print-libdir
Reading available packages...
index-state(hackage.haskell.org) = 2017-07-06T13:22:11Z
Searching for pkg-config in path.
Found pkg-config at /usr/bin/pkg-config
/usr/bin/pkg-config --version
/usr/bin/pkg-config is version 0.29.1
/usr/bin/pkg-config --list-all
...   # finishes everything just fine without consuming significant memory

Whereas with the GHC-HEAD-built version of the same cabal-install-2.0.0.0,

[21:24:32]sagemuej@sagemuej-X302LA:/tmp/cbt
$ cabal configure -v3
no user package environment file found at /tmp/cbt
Searching for ghc in path.
Found ghc at /usr/local/bin/ghc
/usr/local/bin/ghc --numeric-version
/usr/local/bin/ghc is version 8.3.20170622
looking for tool ghc-pkg near compiler in /usr/local/bin
candidate locations:
["/usr/local/bin/ghc-pkg","/usr/local/bin/ghc-pkg-ghc-8.3.20170622","/usr/local/bin/ghc-pkg-8.3.20170622","/usr/local/bin/ghc-pkg"]
found ghc-pkg in /usr/local/bin/ghc-pkg
/usr/local/bin/ghc-pkg --version
/usr/local/bin/ghc-pkg is version 8.3.20170622
/usr/local/bin/ghc --supported-languages
/usr/local/bin/ghc --info
creating dist
Reading installed packages...
/usr/local/bin/ghc-pkg dump --global -v0
/usr/local/bin/ghc-pkg dump --user -v0
/usr/local/bin/ghc --print-libdir
Reading available packages...
^C  # at this point, memory goes through the roof

[23Skidoo]

OK, I think we should now report this to GHC devs. BTW, can you try with GHC 8.2 HEAD?

[bgamari]

For the record, I have opened GHC bug #13930 to track this issue. It doesn't appear to affect ghc-8.2. Unfortunately I'm having trouble bisecting it due to #4509.

[23Skidoo]

Closing in favour of GHC bug #13930.

[hvr]

@bgamari how are you building cabal? are recompiling latest lib:Cabal or using the prebuilt one included in your GHC 8.2 snapshot? I had the impression that #4509 was merely a result compiling a new exe:cabal against an too old lib:Cabal...

[bgamari]

I'm using a cabal-install and Cabal both from the current v2.0 branch.