E.g.
$ nix upgrade-nix
error: directory '/home/eelco/Dev/nix/inst/bin' does not appear to be part of a Nix profile
instead of
$ nix upgrade-nix
error: '/home/eelco/Dev/nix/inst' is not a symlink
The profile present in PATH is not necessarily the actual profile
location. User profiles are generally added as $HOME/.nix-profile
in which case the indirect profile link needs to be resolved first.
/home/user/.nix-profile -> /nix/var/nix/profiles/per-user/user/profile
/nix/var/nix/profiles/per-user/user/profile -> profile-15-link
/nix/var/nix/profiles/per-user/user/profile-14-link -> /nix/store/hyi4kkjh3bwi2z3wfljrkfymz9904h62-user-environment
/nix/var/nix/profiles/per-user/user/profile-15-link -> /nix/store/6njpl3qvihz46vj911pwx7hfcvwhifl9-user-environment
To upgrade nix here we want /nix/var/nix/profiles/per-user/user/profile-16-link
instead of /home/user/.nix-profile-1-link. The latter is not a gcroot
and would be garbage collected, resulting in a broken profile.
Fixes#2175
EvalState contains a few counters (e.g. nrValues) that increase
quickly enough that they end up being interpreted as pointers by the
garbage collector. Moving it to the heap makes them invisible to the
garbage collector.
This reduces the max RSS doing 100 evaluations of
nixos.tests.firefox.x86_64-linux.drvPath from 455 MiB to 292 MiB.
Note: ideally, allocations would be much further up in the 64-bit
address space to reduce the odds of an integer being misinterpreted as
a pointer. Maybe we can use some linker magic to move the .bss segment
to a higher address.
