`stack path` is slower than usual

[fredefox]

General summary/comments (optional)

Running stack path --compiler-bin prompts stack to start "Populating index cache" this is new behavior and didn't happen before. The issue for me is that I use this command in my shells login-script and it slows down initialization considerably.

My issue could be worked around if the stack installation maintained setting global environment variables.

I also do realize that this is perhaps not a standard use-case, however, I would like to have the programs that stack installs (ghc etc.) globally available and this is how I did this.

Steps to reproduce

For example:

1. Log in to a new shell.
2. Run command stack path --compiler-bin or simply stack path.

Expected

The path is printed immediately.

Actual

It prints

"Populating index cache ... <delete line character / CR?>
Populated index cache."

Stack version

$ stack --version
Version 1.5.1, Git revision 600c1f01435a10d127938709556c1682ecfd694e (4861 commits) x86_64 hpack-0.17.1

Method of installation

I believe I used the one-liner from this site https://docs.haskellstack.org/en/stable/install_and_upgrade/

[mgsloan]

Makes sense, shouldn't need to populate the index in order to do stack path.

[andrewcchen]

stack path is also slow for me, but I don't see "Populating index cache".

When I run stack path -v, I can see that it hangs on decoding build plan for more than 1 second.

2017-09-23 16:03:28.548437: [debug] Decoding build plan from: /home/andrew/.stack/build-plan/lts-9.5.yaml
@(Stack/Snapshot.hs:151:5)                                                                                                              
2017-09-23 16:03:29.722151: [debug] Run process: /sbin/ldconfig -p
@(System/Process/Log.hs:37:3)                                                                                                           

[ivan-m]

I also commented on this in #3423

[fredefox]

This behavior is back with:

Version 1.4.0, Git revision 5986498a9d1073e8d58c79ec1302bb2a7847a396 (4642 commits) x86_64 hpack-0.17.0

[danbroooks]

I have done a PR that implements a speed improvement for this command: #5645 I just thought I would mention here that when implementing that PR, on v2.7.3 I do not see this Populating index cache message. Given that this issue is quite old, and relates to version v1.4.0 it might be that this is no longer an issue with stack?