mirror of
https://github.com/NixOS/nix.git
synced 2025-11-22 02:09:36 +01:00
ef8dc34bd0
Previous code had a sneaky bug due to which no caching
actually happened:
```cpp
auto linesForInput = (*lines)[origin->offset];
```
That should have been:
```cpp
auto & linesForInput = (*lines)[origin->offset];
```
See [1].
Now that it also makes sense to make the cache bound in side
in order not to memoize all the sources without freeing any memory.
The default cache size has been chosen somewhat arbitrarily to be ~64k
origins. For reference, 25.05 nixpkgs has ~50k .nix files.
Simple benchmark:
```nix
let
pkgs = import <nixpkgs> { };
in
builtins.foldl' (acc: el: acc + el.line) 0 (
builtins.genList (x: builtins.unsafeGetAttrPos "gcc" pkgs) 10000
)
```
(After)
```
$ hyperfine "result/bin/nix eval -f ./test.nix"
Benchmark 1: result/bin/nix eval -f ./test.nix
Time (mean ± σ): 292.7 ms ± 3.9 ms [User: 131.0 ms, System: 120.5 ms]
Range (min … max): 288.1 ms … 300.5 ms 10 runs
```
(Before)
```
hyperfine "nix eval -f ./test.nix"
Benchmark 1: nix eval -f ./test.nix
Time (mean ± σ): 666.7 ms ± 6.4 ms [User: 428.3 ms, System: 191.2 ms]
Range (min … max): 659.7 ms … 681.3 ms 10 runs
```
If the origin happens to be a `all-packages.nix` or similar in size then the
difference is much more dramatic.
[1]:
|
||
|---|---|---|
| .. | ||
| build-remote | ||
| external-api-docs | ||
| internal-api-docs | ||
| libcmd | ||
| libexpr | ||
| libexpr-c | ||
| libexpr-test-support | ||
| libexpr-tests | ||
| libfetchers | ||
| libfetchers-c | ||
| libfetchers-tests | ||
| libflake | ||
| libflake-c | ||
| libflake-tests | ||
| libmain | ||
| libmain-c | ||
| libstore | ||
| libstore-c | ||
| libstore-test-support | ||
| libstore-tests | ||
| libutil | ||
| libutil-c | ||
| libutil-test-support | ||
| libutil-tests | ||
| nix | ||
| nix-build | ||
| nix-channel | ||
| nix-collect-garbage | ||
| nix-copy-closure | ||
| nix-env | ||
| nix-instantiate | ||
| nix-store | ||
| perl | ||
| nix-functional-tests | ||
| nix-manual | ||