Direct issues to templates instead of GitHub Discussions#8685
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Remove the Discussions redirect from the issue chooser and add Feature Request and Question issue forms in its place. Update CONTRIBUTING.md and the docs to point at issues (or Slack) rather than Discussions, and fix bug_report.yml to apply the existing "bug" label instead of the nonexistent "needs-triage". Signed-off-by: Connor Tsui <connor.tsui20@gmail.com>
robert3005
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Jul 8, 2026
Merging this PR will not alter performance
Warning Please fix the performance issues or acknowledge them on CodSpeed. Performance Changes
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robert3005
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Jul 14, 2026
A small pool of microbenchmarks flips ±10-35% between two fixed values on unrelated PRs (including docs-only and lockfile-only changes), spamming every CodSpeed report. This PR fixes them (and removes only 1 benchmark). No `#[cfg(codspeed)]` gating; CI and local runs stay identical. One commit per benchmark. ## Changes - **mimalloc as global allocator** in the 5 flaky `vortex-array` bench files: `chunk_array_builder`, `dict_compress`, `varbinview_compact`, `compare`, `binary_ops` - **`bitwise_not_vortex_buffer_mut`**: drop the 128/1024/2048 sizes (measured only harness overhead) - **`slice_empty_vortex`**: rewrite as a 1024-iteration tight loop, renamed `slice_empty_tight_loop_vortex` - **`rebuild_naive` (vortex-zstd)**: the one benchmark removed instead of fixed — its cost is dominated by zstd-internal copies (glibc `ifunc`-resolved `memcpy`) that no bench-level change can stabilize, its fixture is degenerate (a 4-string dictionary with all-zero offsets), and ListView rebuild is already benchmarked across element types and list shapes in `vortex-array/benches/listview_rebuild.rs`. The crate's now-unused `divan` dev-dependency goes with it. <details> <summary>Which benchmarks were flaky, and the evidence</summary> Identified by reading the CodSpeed comments on the ~47 PRs merged since June 25 (post-#8490). The tell: the same benchmark flipping between the same two values, in both directions, on PRs that can't have affected it — including deny.toml-only (#8712, #8716), uv.lock-only (#8732), docs-only (#8737, #8728, #8685), and CI-YAML-only (#8660, #8683) changes. | Benchmark | Evidence | |---|---| | `bitwise_not_vortex_buffer_mut[128/1024/2048]` | ~half of all PRs — worst offender | | `chunked_varbinview_*` ×4 | ~20 PRs, both directions | | `chunked_bool_canonical_into[(1000,10)]` | ~2× flips (16µs ↔ 35µs) on 4 PRs | | `encode_varbin`, `encode_varbinview` | ~12 PRs; `encode_varbinview[(10000,4)]` also flipped on an earlier revision of this PR | | `compact`, `compact_sliced` (90%-utilization args) | ~8 PRs | | `compare_int_constant` | ±11.1% verbatim on ≥9 PRs | | `eq_i64_constant` | same ±11% signature incl. docs-only PR | | `slice_empty_vortex` | -14.66% verbatim on ~13 PRs | | `rebuild_naive` (vortex-zstd) | ~10 PRs, both directions | Watch list (left alone, below the ≥3-independent-sightings bar): `copy_nullable`/`copy_non_nullable[65536]` in `cast_decimal.rs`, `true_count_vortex_buffer[128]`. </details> <details> <summary>Root causes and why each fix matches</summary> - **Allocation in the timed region** → glibc malloc's code differs across CodSpeed runner images, so alloc-heavy benchmarks trace differently for byte-identical Vortex code. Vendored mimalloc removes glibc malloc from the trace. Empirical support: the only three bench files already using mimalloc (`single_encoding_throughput`, `common_encoding_tree_throughput`, `row_encode`) are the most alloc-heavy suites in the repo and were never flagged once in the 47-PR window. - **Sub-microsecond work** → the measurement is fixed harness overhead plus binary code layout, which shifts with any unrelated change. Fix by making the operation dominate: the in-place NOT (no alloc, no copy) keeps only sizes where the loop dominates; the empty slice runs 1024× per iteration, mirroring the neighboring `slice_tight_loop_vortex`. - **Environment-bound and low-signal** → `rebuild_naive`, per the justification above: unfixable at the bench level and redundant with the vortex-array ListView rebuild suite, so removed. </details> <details> <summary>Validation: A/A reruns and a stacked canary PR</summary> - **Expected one-time step changes on this PR**: swapping the allocator changes the trace of every benchmark in the touched files, so this PR's report shows a few ±10-20% level shifts (including on never-flaky `encode_primitives`, which just shares a file). These need a one-time acknowledgment on the CodSpeed dashboard; after merge every PR compares mimalloc-vs-mimalloc. - **A/A reruns** (same bench binaries measured three times, on separate runners and commits): every value reproduced exactly — 211.5µs, 137.1µs, 14.6µs, 26.3µs — with zero new flags across 1656 benchmarks. - **Canary #8743** (a #8681-style cold-string change stacked on this branch — the class of change that used to collect five false flags): **Performance Gate Passed**, `✅ 1660 untouched`, zero changes reported. </details> No public API changes; benchmark-only. https://claude.ai/code/session_01T6PPcdrqcNeUkfi1EGd4oC --------- Signed-off-by: Claude <noreply@anthropic.com> Co-authored-by: Claude <noreply@anthropic.com>
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Rationale for this change
We want to move away from discussions in general because they are not great to work with and everyone is more familiar with issues.
What changes are included in this PR?
Remove the Discussions redirect from the issue chooser and add Feature Request and Question issue forms in its place. Update CONTRIBUTING.md and the docs to point at issues (or Slack) rather than Discussions, and fix bug_report.yml to apply the existing "bug" label instead of the nonexistent "needs-triage".
What APIs are changed? Are there any user-facing changes?
N/A