Dandandan opened a new pull request, #24342:
URL: https://github.com/apache/datafusion/pull/24342
## Which issue does this PR close?
None. Found while profiling compile times (#24325, #24326, #24329, #24330,
#24338, #24339) — this is the largest remaining item I measured.
## Rationale for this change
`datafusion-functions` declares **63 `[[bench]]` targets**. Each one is a
separate binary that statically links this crate, arrow and criterion, so
building the crate's benchmarks means 63 link steps.
Linking, not compiling, is the bulk of it: rebuilding a **single** bench
target
takes **10.6s**, almost all of it link, and the 63 benchmark files together
are
only ~10.5k lines of source.
This is paid by `cargo bench`, by `cargo build --all-targets`, and by CI's
`clippy --all-targets`.
## What changes are included in this PR?
The targets are grouped by their `required-features`, which preserves that
semantics exactly — a group can only be built when its feature is on, just as
each individual bench could before:
| target | benches | required-features |
|---|---|---|
| `string_expressions` | 16 | `["string_expressions"]` |
| `math_expressions` | 16 | `["math_expressions"]` |
| `unicode_expressions` | 12 | `["unicode_expressions"]` |
| `datetime_expressions` | 8 | `["datetime_expressions"]` |
| `regex_expressions` | 4 | `["regex_expressions"]` |
| `misc` | 4 | none |
`crypto`, `encoding` and `dictionary_encoding` stay standalone — they are the
only members of their feature groups, so grouping them would buy nothing.
Each group file declares the individual benchmarks as modules and lists their
criterion groups in a single `criterion_main!`. `autobenches = false` stops
cargo
from picking the module files back up as targets of their own.
**The benchmark code itself is untouched.** There is not a single change to a
`bench_function`, `benchmark_group` or `bench_with_input` line anywhere in
the
diff. Per file the change is only:
- drop `criterion_main!` — a module cannot define `main`
- drop the now-unused `criterion_main` import
- drop `extern crate criterion` (a no-op since edition 2018, present in 4
files)
- point the four users of `benches/helper.rs` at `crate::helper`
which is why 60 of the 67 changed files have a one- or two-line diff.
## Are these changes tested?
Interleaved with `main` so machine drift cancels out:
| `cargo clean -p datafusion-functions` then… | main (63 targets) | this PR
(9 targets) |
|---|---|---|
| `cargo build --benches` | 66.5s / 43.9s | **29.3s / 29.9s** |
| `cargo check --benches` | 15.9s / 15.3s | **13.0s / 13.2s** |
(The build column is noisier on `main` — 63 concurrent link steps contend for
I/O — hence quoting both runs rather than an average.)
Correctness, all on this branch:
- `cargo bench --bench string_expressions -- --test` runs **252** benchmarks
- `cargo bench --bench crypto --features crypto_expressions -- --test` runs
10,
`encoding` 9, `dictionary_encoding` 36
- filtering a single benchmark still works:
`cargo bench --bench math_expressions -- power` → runs just that one
- `cargo clippy -p datafusion-functions --all-targets` and `cargo fmt
--check`
are both clean
- `cargo metadata` confirms 9 bench targets
## Are there any user-facing changes?
Only for running an individual benchmark. Where you would previously write
```
cargo bench -p datafusion-functions --bench lower
```
you now select the group and filter by name:
```
cargo bench -p datafusion-functions --bench string_expressions -- lower
```
The filter is criterion's own, matching on benchmark id, so it also narrows
to a
single case within a benchmark. No library changes.
If this approach looks right, roughly 100 more bench targets across the other
crates could get the same treatment — I did this one crate first so the
tradeoff
is visible on a real diff before it spreads.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
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