perf: reduce SQL round-trips in scheduler hot paths#57
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The iterative BFS issued one SQL round-trip per graph node, producing O(n²) total queries for linear dependency chains (~19,900 for depth 200). A single recursive CTE collapses each cycle check to one query, yielding an 82% speedup at depth 200.
Combine completion + dependency resolution into a single transaction, cache next_run_after to skip the query when no scheduled tasks exist, carry tags from peek to pop to avoid a redundant populate_tags query, skip tag queries entirely when the store has never had tags inserted, and skip the paused_tasks query when no tasks have been preempted. Benchmarked at ~40% improvement on dep_chain_dispatch/50 (42ms → 26ms) and ~20-34% on fan-in dispatch benchmarks.
…-trips - Batch resolve_dependency_edges: replace 3N per-dep queries (history check, active check, edge insert) with 3 batch queries using IN clauses - Single-pass cycle detection: seed one recursive CTE with all dep IDs instead of running N separate CTEs - Replace pop_by_id_no_tags (UPDATE RETURNING *) with claim_task (UPDATE only), reusing the TaskRecord already fetched by peek_next Benchmarked improvement on dep_fan_in_dispatch: width=10: -15% (5.2ms → 4.4ms) width=50: -19% (21.7ms → 17.5ms) width=100: -14% (40.5ms → 34.8ms)
…mpatibility Move pprof to an optional dependency gated by a `profile` feature so benchmarks can run in CI without requiring perf_event_open. Local profiling is still available via `cargo bench --features profile`. Also simplify TTL expiry check in run_loop to use if-let instead of unwrap.
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deepjoy
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## 🤖 New release * `taskmill`: 0.5.1 -> 0.5.2 (✓ API compatible changes) <details><summary><i><b>Changelog</b></i></summary><p> <blockquote> ## [0.5.2](v0.5.1...v0.5.2) - 2026-03-19 ### Other - reduce SQL round-trips and CPU overhead in scheduler hot paths ([#60](#60)) - coalesce task completions into batched transactions ([#59](#59)) - reduce SQL round-trips in scheduler hot paths ([#57](#57)) </blockquote> </p></details> --- This PR was generated with [release-plz](https://github.com/release-plz/release-plz/). Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
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Summary
complete_with_record_and_resolvecombines thecomplete_with_recordandresolve_dependentscalls, eliminating aBEGIN IMMEDIATE/COMMITcycle on every task completion.has_paused_tasks(atomic bool) skips thepaused_tasks()query when nothing has been preempted;has_tagsskipspopulate_tagswhen no tags exist;check_scheduledskipsnext_run_afterwhen no scheduled tasks are present.claim_taskuses a simpleUPDATE … SET status='running'withoutRETURNING *, patching the already-held in-memoryTaskRecordinstead of re-fetching the full row.profilefeature: Movespproffrom a mandatory dev-dependency to an optional feature, fixing CI builds on platforms where pprof fails to compile.Module→Domain<D>API transition.