docker-tools tests load images without specifying any tag
value. Docker then uses the image with tag "latest" which doesn't
exist anymore since commit 39e678e24e38f1f374eaf5463b424ebdf75df9af.
Need to use fetchFromGitHub because examples/ is missing from PyPI tarball.
Also clean up the expression and specify appropriate checkInputs.
Fixes#42867.
I'm a little confused as to why this buils and runs on darwin, but fails to
build without it on linux. The error was:
```go/src/github.com/gxed/eventfd/eventfd.go:17:2: cannot find package "github.com/gxed/GoEndian" in any of:```
Fixes#43015 for me and hopefully also similar issues.
== Resource consumption ==
TL;DR: no change for small-memory cases, less CPU for large-memory cases.
I assume almost all of the large memory usage is just the expression
evaluation and managed by the GC, so I used just `nix-env -q...` to test.
Old and new lines for each command follow. I tried to run each several
times, but the values were very stable (<1% difference on re-runs),
so only one line for each command-version pair is provided.
$ time nix-env -f . -qaP --description -A nix >/dev/null
- 0.06user 0.01system 0:00.07elapsed 101%CPU (0avgtext+0avgdata 29036maxresident)k
+ 0.06user 0.01system 0:00.07elapsed 102%CPU (0avgtext+0avgdata 29864maxresident)k
$ time nix-env -f . -qaP --description >/dev/null
- 6.45user 0.36system 0:06.82elapsed 99%CPU (0avgtext+0avgdata 1021024maxresident)k
+ 6.23user 0.33system 0:06.57elapsed 100%CPU (0avgtext+0avgdata 938408maxresident)k
$ time nix-env -f . --show-trace -qa --drv-path --system --meta --xml 2>&1 >/dev/null
- 56.35user 0.96system 0:31.03elapsed 184%CPU (0avgtext+0avgdata 3207708maxresident)k
+ 44.80user 0.91system 0:26.12elapsed 175%CPU (0avgtext+0avgdata 3192696maxresident)k
$ time ./result-nix-large/bin/nix-instantiate --dry-run --eval --strict \
--show-trace ./maintainers/scripts/eval-release.nix > /dev/null
- Too many heap sections: Increase MAXHINCR or MAX_HEAP_SECTS
- Command terminated by signal 6
- 175.18user 2.68system 1:17.42elapsed 229%CPU (0avgtext+0avgdata 8468440maxresident)k
+ 178.48user 2.78system 1:15.11elapsed 241%CPU (0avgtext+0avgdata 8460572maxresident)k
"if platforms is not set it will default to go.meta.platforms which is probably
what you want" And that does sound like what we want. Also, the linux build was
complaining about eventfd, or the lack thereof.
