Normalize burst handling for unlimited bandwidth limits#1192
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…nalysis (#1192) Static analysis of every Arc<Mutex<Vec<...>>> remaining in the workspace, focused on the parallel stat hot path. Confirms parallel stat does not allocate any shared mutex-guarded accumulator: map_blocking delegates to rayon's into_par_iter().map().collect() with per-task buffers internal to rayon. Three production sites remain (SSH stderr drain x2, drain_parallel shards), only the third is on a rayon hot path and is sharded already. Cites the just-merged drain-side audit (PR #3699) for the drain-shards analysis, scopes #1192 to runtime profiling needed for closure, and lists mitigations to evaluate only if profiling surfaces a residual Mutex<Vec>.
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…nalysis (#1192) (#3727) Static analysis of every Arc<Mutex<Vec<...>>> remaining in the workspace, focused on the parallel stat hot path. Confirms parallel stat does not allocate any shared mutex-guarded accumulator: map_blocking delegates to rayon's into_par_iter().map().collect() with per-task buffers internal to rayon. Three production sites remain (SSH stderr drain x2, drain_parallel shards), only the third is on a rayon hot path and is sharded already. Cites the just-merged drain-side audit (PR #3699) for the drain-shards analysis, scopes #1192 to runtime profiling needed for closure, and lists mitigations to evaluate only if profiling surfaces a residual Mutex<Vec>.
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Add criterion microbench under crates/transfer/benches profiling four result-collection strategies (shared Arc<Mutex<Vec>>, sharded Mutex<Vec> by rayon worker id, crossbeam SegQueue, crossbeam unbounded channel) over 100K items at 1/4/8/16 rayon worker counts. Throughput is reported in elements/sec so the bench output names the worker count at which the single shared mutex saturates. The shipping parallel-stat path in crates/transfer/src/parallel_io.rs does not use Arc<Mutex<Vec>>; it collects via into_par_iter().map(f).collect(), which delegates to rayon's lock-free reducer. Document this in docs/audits/parallel-stat-collection.md and keep the microbench as the baseline against which any future PR that proposes reintroducing a shared mutex on this path must be measured (tracked under #1192, #1271, #1297, #1370, #1682).
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… (#4170) * chore(bench): add parallel-stat collector contention microbench Add criterion microbench under crates/transfer/benches profiling four result-collection strategies (shared Arc<Mutex<Vec>>, sharded Mutex<Vec> by rayon worker id, crossbeam SegQueue, crossbeam unbounded channel) over 100K items at 1/4/8/16 rayon worker counts. Throughput is reported in elements/sec so the bench output names the worker count at which the single shared mutex saturates. The shipping parallel-stat path in crates/transfer/src/parallel_io.rs does not use Arc<Mutex<Vec>>; it collects via into_par_iter().map(f).collect(), which delegates to rayon's lock-free reducer. Document this in docs/audits/parallel-stat-collection.md and keep the microbench as the baseline against which any future PR that proposes reintroducing a shared mutex on this path must be measured (tracked under #1192, #1271, #1297, #1370, #1682). * chore: sync Cargo.lock after dev-dep addition
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May 18, 2026
…nalysis (#1192) (#3727) Static analysis of every Arc<Mutex<Vec<...>>> remaining in the workspace, focused on the parallel stat hot path. Confirms parallel stat does not allocate any shared mutex-guarded accumulator: map_blocking delegates to rayon's into_par_iter().map().collect() with per-task buffers internal to rayon. Three production sites remain (SSH stderr drain x2, drain_parallel shards), only the third is on a rayon hot path and is sharded already. Cites the just-merged drain-side audit (PR #3699) for the drain-shards analysis, scopes #1192 to runtime profiling needed for closure, and lists mitigations to evaluate only if profiling surfaces a residual Mutex<Vec>.
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… (#4170) * chore(bench): add parallel-stat collector contention microbench Add criterion microbench under crates/transfer/benches profiling four result-collection strategies (shared Arc<Mutex<Vec>>, sharded Mutex<Vec> by rayon worker id, crossbeam SegQueue, crossbeam unbounded channel) over 100K items at 1/4/8/16 rayon worker counts. Throughput is reported in elements/sec so the bench output names the worker count at which the single shared mutex saturates. The shipping parallel-stat path in crates/transfer/src/parallel_io.rs does not use Arc<Mutex<Vec>>; it collects via into_par_iter().map(f).collect(), which delegates to rayon's lock-free reducer. Document this in docs/audits/parallel-stat-collection.md and keep the microbench as the baseline against which any future PR that proposes reintroducing a shared mutex on this path must be measured (tracked under #1192, #1271, #1297, #1370, #1682). * chore: sync Cargo.lock after dev-dep addition
oferchen
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May 18, 2026
… (#4170) * chore(bench): add parallel-stat collector contention microbench Add criterion microbench under crates/transfer/benches profiling four result-collection strategies (shared Arc<Mutex<Vec>>, sharded Mutex<Vec> by rayon worker id, crossbeam SegQueue, crossbeam unbounded channel) over 100K items at 1/4/8/16 rayon worker counts. Throughput is reported in elements/sec so the bench output names the worker count at which the single shared mutex saturates. The shipping parallel-stat path in crates/transfer/src/parallel_io.rs does not use Arc<Mutex<Vec>>; it collects via into_par_iter().map(f).collect(), which delegates to rayon's lock-free reducer. Document this in docs/audits/parallel-stat-collection.md and keep the microbench as the baseline against which any future PR that proposes reintroducing a shared mutex on this path must be measured (tracked under #1192, #1271, #1297, #1370, #1682). * chore: sync Cargo.lock after dev-dep addition
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Summary
BandwidthLimitComponents::newdiscards burst hints when the limit is unlimited so the helper mirrors upstream semanticsTesting
https://chatgpt.com/codex/tasks/task_e_68feb929c0f883239435fad25fb3d8c1