feat(numa): introduce I/O sampling to prevent activation stalls

Replaces the monolithic CPU scaling threshold with separate CPU and I/O spawn thresholds. Introduces an `IoSample` struct with platform-specific byte reading and a relative throughput growth heuristic. Adds a 0.1s wall-clock guard to `CpuSample` to suppress artificial efficiency spikes, and updates `maybe_activate` to trigger worker scaling when either resource indicates headroom. Bumps `obikmer` to v1.1.33 and updates architecture documentation.

.gitea/workflows/release.yml

@@ -86,17 +86,12 @@ jobs:
   build-macos-arm64:
     needs: create-release
     runs-on: ubuntu-latest
-    container:
-      image: registry.metabarcoding.org/cibuilder/rustcrossosx:latest
-      credentials:
-        username: ${{ github.actor }}
-        password: ${{ secrets.REGISTRYTOKEN }}
-    defaults:
-      run:
-        working-directory: src
     steps:
       - uses: actions/checkout@v4
 
+      - name: Login to registry
+        run: echo "${{ secrets.REGISTRYTOKEN }}" | docker login registry.metabarcoding.org -u ${{ secrets.REGISTRYUSER }} --password-stdin
+
       - name: Cache cargo registry
         uses: actions/cache@v4
         with:
@@ -108,7 +103,12 @@ jobs:
           restore-keys: macos-arm64-cargo-
 
       - name: Build macOS binary
-        run: cargo build --release --target aarch64-apple-darwin --no-default-features
+        run: |
+          docker run --rm \
+            -v "${{ github.workspace }}:/src" \
+            -w /src/src \
+            registry.metabarcoding.org/cibuilder/rustcrossosx:latest \
+            cargo build --release --target aarch64-apple-darwin --no-default-features
 
       - name: Prepare and upload artifact
         env:
@@ -116,7 +116,7 @@ jobs:
           RELEASE_ID: ${{ needs.create-release.outputs.release_id }}
         run: |
           mkdir -p /tmp/dist
-          cp target/aarch64-apple-darwin/release/obikmer /tmp/dist/obikmer-macos-arm64
+          cp src/target/aarch64-apple-darwin/release/obikmer /tmp/dist/obikmer-macos-arm64
           curl -s -X POST \
             "${{ github.server_url }}/api/v1/repos/${{ github.repository }}/releases/$RELEASE_ID/assets" \
             -H "Authorization: token $GITEA_TOKEN" \

.gitignore

@@ -8,6 +8,7 @@ data-stress
 *.pb
 ./**/*.json
 *.bin
+*.log
 Betula_exilis--IGA-24-33
 benchmark/genomes
 benchmark/simulated_data

docmd/architecture/numa_partition_runner.md

@@ -162,14 +162,107 @@ A single `PartitionRunner` instance can be built once per command invocation
 and reused across multiple `run()` calls (e.g. `merge` runs
 `merge_partitions` then `pack_matrices`).
 
+## Known issue: CPU-only activation signal stalls on I/O-bound stages
+
+Observed on a real `filter` run (109 genomes, 256 partitions, 8×24-core NUMA):
+`rebuild` (CPU-bound — k-mer construction) scales cleanly from 9 to 43 active
+workers as `CpuSample::do_i_activate` (`obisys::lib.rs`) sees efficiency climb.
+`pack_matrices` (I/O-bound — reopens and recomposes per-genome column files
+into `.pbmx`/`.pcmx`) activates one extra worker then flatlines at 10/192 for
+the rest of the stage, even though 256 partitions keep completing over several
+minutes. This matches the documented intent (§ Adaptive mechanism — "avoids
+over-provisioning ... I/O-bound ... workloads") but conflates two different
+things: *"CPU is not the bottleneck"* and *"more workers would not help"*. On
+storage with real queue depth (NVMe, RAID, parallel FS) the second stage could
+still benefit from more concurrent workers even with flat CPU usage — a signal
+the current mechanism cannot see.
+
+A one-off artefact was also found in the same log: right after a stage
+transition, `do_i_activate` produced a physically impossible spike (efficiency
+~94 cores on a 192-core box) because it has no minimum-window guard — unlike
+its sibling `cpu_efficiency`, which returns `0.0` if `wall < 0.1s`
+(`obisys::lib.rs:260`). `do_i_activate` unconditionally overwrites
+`self.wall`/`self.user_secs`/`self.sys_secs` even when the elapsed window is
+too short to be meaningful, so a burst of rapid completions right after
+activating a worker can divide a real CPU delta by a near-zero wall delta.
+
+### Implemented: I/O signal + shared debounce guard
+
+`IoSample` (`obisys::lib.rs`, alongside `CpuSample`) is fed by
+`read_bytes`/`write_bytes` from `/proc/self/io` on Linux (actual bytes
+submitted to the block layer — not `rchar`/`wchar`, which also count
+page-cache hits, and not `ru_inblock`/`ru_oublock`, unreliable on macOS), with
+a `proc_pid_rusage(RUSAGE_INFO_V4)` fallback on macOS
+(`ri_diskio_bytesread`/`ri_diskio_byteswritten`, FFI only via `libc`, no new
+dependency — same pattern as the existing `getrusage` bindings). Any other
+target degrades gracefully to a signal that never triggers (falls back to
+CPU-only activation), same pattern as `cgroup_v2_available`.
+
+`maybe_activate` (`numa.rs`) activates a worker if *either* signal still shows
+headroom, making `PartitionRunner` adapt to whichever resource is actually the
+bottleneck without per-call configuration. Both samplers are called
+unconditionally — no `||` short-circuit — so neither window starves behind
+whichever signal fires first:
+
+```rust
+let cpu_wants_more = cpu_sample.do_i_activate(CPU_SPAWN_THRESHOLD);
+let io_wants_more  = io_sample.do_i_activate(IO_SPAWN_THRESHOLD);
+if cpu_wants_more || io_wants_more {
+    activate_tx.send(()).ok();
+    ...
+}
+```
+
+Unlike the CPU signal (an absolute delta in cores — a bounded, portable unit),
+raw I/O throughput has no natural scale across devices, so `IoSample` uses a
+**relative** growth threshold instead of an absolute one:
+
+```rust
+pub fn do_i_activate(&mut self, threshold: f64) -> bool {
+    let elapsed = self.wall.elapsed().as_secs_f64();
+    if elapsed < 0.1 { return false; }        // state untouched — window keeps accumulating
+
+    let n = Self::read_bytes();
+    let rate = n.saturating_sub(self.bytes) as f64 / elapsed;
+    let activate = if self.previous_rate == 0.0 {
+        rate > 0.0                            // bootstrap: any measured throughput is signal
+    } else {
+        (rate - self.previous_rate) / self.previous_rate >= threshold
+    };
+
+    self.bytes = n;
+    self.wall  = Instant::now();              // reset only on a real sample
+    activate
+}
+```
+
+The `elapsed < 0.1s → return false without mutating state` guard was also
+back-ported into `CpuSample::do_i_activate` (previously missing — source of
+the ~94-core artefact above) — one fix for both problems, and it removes the
+need for any arbitrary I/O-rate floor: a short/noisy window is rejected
+outright rather than papered over with a hardware-dependent constant.
+
+Both spawn thresholds (`CPU_SPAWN_THRESHOLD`, `IO_SPAWN_THRESHOLD`, both `0.2`)
+are defined as `const` in `PartitionRunner::run` (`numa.rs`). The I/O value is
+a starting point, not a derived one — needs empirical validation against a
+real `pack` run.
+
+Starting threshold: `0.2` (20 % relative growth) for `IoSample`, same order of
+magnitude as the CPU threshold's *implicit* relative sensitivity (in the
+observed log, an 8→9 worker step raised efficiency by ~12 %). This is a
+starting point, not a derived value — I/O throughput is lumpier than CPU time
+(buffered writes flush in bursts), so it needs empirical validation against a
+real `pack` run before being considered final.
+
 ## Open questions
 
 - **Error handling**: `run` currently returns the first error; remaining errors
   are dropped.  A `Vec<E>` return would give complete diagnostics.
 
 - **`workers_per_node` tuning**: currently `(cpus / 8).max(3).min(8)`, calibrated
-  for merge on BeeGFS.  I/O-bound commands (`dump`, `select`) may benefit from
+  for merge on BeeGFS.  Superseded by the I/O signal above for the "more
-  a higher value.  A per-call override could be added to the API.
+  workers would help despite flat CPU" case — a per-call override may still be
+  worth keeping as a manual escape hatch.
 
 - **`on_done` ordering**: the runner serialises calls to `on_done` via an
   internal `Arc<Mutex<C>>`.  `Send` is required (the Arc clone crosses thread

src/Cargo.lock

@@ -1704,7 +1704,7 @@ dependencies = [
 
 [[package]]
 name = "obikmer"
-version = "1.1.27"
+version = "1.1.33"
 dependencies = [
  "clap",
  "csv",

src/obikindex/src/numa.rs

@@ -20,7 +20,7 @@ use hwlocality::cpu::binding::CpuBindingFlags;
 use hwlocality::cpu::cpuset::CpuSet;
 #[cfg(feature = "numa")]
 use hwlocality::object::types::ObjectType;
-use obisys::CpuSample;
+use obisys::{CpuSample, IoSample};
 use tracing::debug;
 
 // ── Public interface ──────────────────────────────────────────────────────────
@@ -190,10 +190,13 @@ impl PartitionRunner {
     /// Run `f(i)` for every index in `order`.
     ///
     /// Workers are pre-spawned dormant and activated adaptively. A timer thread
-    /// fires a CPU-efficiency check every `TIMER_SECS` seconds; each completed
+    /// fires an efficiency check every `TIMER_SECS` seconds; each completed
     /// partition resets that timer (forcing an immediate check) and also
-    /// triggers its own inline check. A new worker is activated whenever
+    /// triggers its own inline check. A new worker is activated whenever CPU
-    /// efficiency falls below `SPAWN_THRESHOLD`.
+    /// efficiency grows by at least `CPU_SPAWN_THRESHOLD` (absolute, in cores)
+    /// or I/O throughput grows by at least `IO_SPAWN_THRESHOLD` (relative) since
+    /// the last check — whichever resource is the actual bottleneck still shows
+    /// headroom.
     ///
     /// `on_done(i, result, elapsed)` is called from the controller thread as
     /// each partition completes — suitable for progress bars and result
@@ -217,13 +220,10 @@ impl PartitionRunner {
             return Ok(());
         }
 
-        const SPAWN_THRESHOLD: f64 = 0.95;
+        const CPU_SPAWN_THRESHOLD: f64 = 0.2;
+        const IO_SPAWN_THRESHOLD:  f64 = 0.2;
         const TIMER_SECS:          u64 = 30;
 
-        let n_cores = std::thread::available_parallelism()
-            .map(|n| n.get())
-            .unwrap_or(1);
-
         // ── Channels ──────────────────────────────────────────────────────────
         let (part_tx,     part_rx)     = unbounded::<usize>();
         let (activate_tx, activate_rx) = unbounded::<()>();
@@ -291,7 +291,7 @@ impl PartitionRunner {
             for _ in 0..initial_workers { activate_tx.send(()).ok(); }
             let mut n_active   = initial_workers;
             let mut cpu_sample = CpuSample::now();
-            let mut eff_at_last_spawn     = 0.0f64; // 0 = no previous spawn to evaluate
+            let mut io_sample  = IoSample::now();
             let mut completed  = 0usize;
 
             while completed < n_total {
@@ -308,15 +308,17 @@ impl PartitionRunner {
                         // Inline check: same logic as a timer tick.
                         maybe_activate(
                             &activate_tx, &mut n_active, max_workers,
-                            &mut cpu_sample, &mut eff_at_last_spawn,
+                            &mut cpu_sample, CPU_SPAWN_THRESHOLD,
-                            n_cores, SPAWN_THRESHOLD, completed, n_total,
+                            &mut io_sample, IO_SPAWN_THRESHOLD,
+                            completed, n_total,
                         );
                     }
                     WorkerEvent::TimerTick => {
                         maybe_activate(
                             &activate_tx, &mut n_active, max_workers,
-                            &mut cpu_sample, &mut eff_at_last_spawn,
+                            &mut cpu_sample, CPU_SPAWN_THRESHOLD,
-                            n_cores, SPAWN_THRESHOLD, completed, n_total,
+                            &mut io_sample, IO_SPAWN_THRESHOLD,
+                            completed, n_total,
                         );
                     }
                 }
@@ -347,38 +349,23 @@ fn maybe_activate(
     n_active:      &mut usize,
     max_workers:   usize,
     cpu_sample:    &mut CpuSample,
-    eff_at_last_spawn:   &mut f64,
+    cpu_threshold: f64,
-    n_cores:             usize,
+    io_sample:     &mut IoSample,
-    threshold:           f64,
+    io_threshold:  f64,
     completed:     usize,
     n_total:       usize,
 ) {
     if *n_active >= max_workers || completed >= n_total { return; }
 
-    let eff = cpu_sample.cpu_efficiency(n_cores);
+    // Call both unconditionally (no `||` short-circuit): each sampler must
-    if eff >= threshold { return; }  // CPU already saturated
+    // advance its own window every tick, regardless of what the other one
+    // reports, or it would starve behind whichever signal fires first.
+    let cpu_wants_more = cpu_sample.do_i_activate(cpu_threshold);
+    let io_wants_more  = io_sample.do_i_activate(io_threshold);
 
-    // Check that the previous activation was beneficial enough.
+    if cpu_wants_more || io_wants_more {
-    // Going from k-1 → k workers, the minimum acceptable speedup is (k-1+0.2)/(k-1).
-    // For the very first extra worker (n_active == 1, no previous spawn), skip this
-    // check: eff_at_last_spawn == 0 acts as the sentinel.
-    let last_spawn_was_beneficial = if *eff_at_last_spawn < 1e-9 || eff < 1e-9 {
-        true  // first additional worker, or measurement too short: no prior data to evaluate
-    } else {
-        let k_new = *n_active as f64;  // worker count after the last spawn
-        let min_gain = 0.2 / k_new;
-        let actual_gain = (eff - *eff_at_last_spawn) / eff;
-        actual_gain >= min_gain
-    };
-
-    if last_spawn_was_beneficial {
         activate_tx.send(()).ok();
-        *eff_at_last_spawn = eff;
         *n_active += 1;
-        *cpu_sample = CpuSample::now();
+        debug!("activated worker {}/{}", n_active, max_workers);
-        debug!(
-            "activated worker {}/{} — efficiency {:.0}%",
-            n_active, max_workers, eff * 100.0,
-        );
     }
 }

src/obikmer/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "obikmer"
-version = "1.1.27"
+version = "1.1.33"
 edition = "2024"
 
 [[bin]]

src/obisys/src/lib.rs

@@ -4,7 +4,7 @@ use std::sync::{Condvar, Mutex};
 use std::time::{Duration, Instant};
 
 use indicatif::{ProgressBar, ProgressStyle};
-use tracing::{info, warn};
+use tracing::{debug, info, warn};
 
 const BRAILLE: &[&str] = &["⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏"];
 
@@ -31,7 +31,8 @@ impl TracedBar {
             let pct10 = (pos * 10) / self.total; // 0..=10
             let last = self.last_pct.load(Ordering::Relaxed);
             if pct10 > last
-                && self.last_pct
+                && self
+                    .last_pct
                     .compare_exchange(last, pct10, Ordering::Relaxed, Ordering::Relaxed)
                     .is_ok()
             {
@@ -49,14 +50,14 @@ impl TracedBar {
         let msg = msg.into();
         if self.pb.is_hidden() {
             if self.total > 0 {
-                // bounded bar: always log (already rate-limited by 10% threshold in inc)
+                debug!(stage = %self.label, "{msg}");
-                info!(stage = %self.label, "{msg}");
             } else {
                 // spinner: throttle to ~10 s
                 let now_ms = self.start.elapsed().as_millis() as u64;
                 let last = self.last_log_ms.load(Ordering::Relaxed);
                 if now_ms >= last + 10_000
-                    && self.last_log_ms
+                    && self
+                        .last_log_ms
                         .compare_exchange(last, now_ms, Ordering::Relaxed, Ordering::Relaxed)
                         .is_ok()
                 {
@@ -83,8 +84,13 @@ pub fn spinner(label: &str) -> TracedBar {
     );
     pb.enable_steady_tick(Duration::from_millis(100));
     TracedBar {
-        pb, label: label.to_string(), unit: String::new(), total: 0,
+        pb,
-        start: Instant::now(), last_pct: AtomicU64::new(0), last_log_ms: AtomicU64::new(0),
+        label: label.to_string(),
+        unit: String::new(),
+        total: 0,
+        start: Instant::now(),
+        last_pct: AtomicU64::new(0),
+        last_log_ms: AtomicU64::new(0),
     }
 }
 
@@ -101,8 +107,13 @@ pub fn progress_bar(label: &str, n: u64, unit: &str) -> TracedBar {
     );
     pb.enable_steady_tick(Duration::from_millis(100));
     TracedBar {
-        pb, label: label.to_string(), unit: unit.to_string(), total: n,
+        pb,
-        start: Instant::now(), last_pct: AtomicU64::new(0), last_log_ms: AtomicU64::new(0),
+        label: label.to_string(),
+        unit: unit.to_string(),
+        total: n,
+        start: Instant::now(),
+        last_pct: AtomicU64::new(0),
+        last_log_ms: AtomicU64::new(0),
     }
 }
 
@@ -204,13 +215,19 @@ fn tv_to_secs(tv: timeval) -> f64 {
 }
 
 #[cfg(target_os = "macos")]
-fn rss_to_bytes(ru: &rusage) -> u64 { ru.ru_maxrss as u64 }
+fn rss_to_bytes(ru: &rusage) -> u64 {
+    ru.ru_maxrss as u64
+}
 
 #[cfg(not(target_os = "macos"))]
-fn rss_to_bytes(ru: &rusage) -> u64 { ru.ru_maxrss as u64 * 1024 }
+fn rss_to_bytes(ru: &rusage) -> u64 {
+    ru.ru_maxrss as u64 * 1024
+}
 
 // Monotonically increasing counters — negative delta would be a kernel bug.
-fn delta(end: i64, start: i64) -> u64 { (end - start).max(0) as u64 }
+fn delta(end: i64, start: i64) -> u64 {
+    (end - start).max(0) as u64
+}
 
 // ── CpuSample ─────────────────────────────────────────────────────────────────
 
@@ -221,6 +238,7 @@ pub struct CpuSample {
     wall: Instant,
     user_secs: f64,
     sys_secs: f64,
+    previous: f64,
 }
 
 impl CpuSample {
@@ -230,6 +248,7 @@ impl CpuSample {
             wall: Instant::now(),
             user_secs: tv_to_secs(ru.ru_utime),
             sys_secs: tv_to_secs(ru.ru_stime),
+            previous: 0.0,
         }
     }
 
@@ -238,11 +257,129 @@ impl CpuSample {
     pub fn cpu_efficiency(&self, n_cores: usize) -> f64 {
         let ru = get_rusage();
         let wall = self.wall.elapsed().as_secs_f64();
-        if wall < 0.1 { return 0.0; }
+        if wall < 0.1 {
-        let cpu = (tv_to_secs(ru.ru_utime) - self.user_secs)
+            return 0.0;
-                + (tv_to_secs(ru.ru_stime) - self.sys_secs);
+        }
+        let cpu =
+            (tv_to_secs(ru.ru_utime) - self.user_secs) + (tv_to_secs(ru.ru_stime) - self.sys_secs);
         cpu / (wall * n_cores as f64)
     }
+
+    pub fn do_i_activate(&mut self, threshold: f64) -> bool {
+        let delta_wall = self.wall.elapsed().as_secs_f64();
+        if delta_wall < 0.1 {
+            // Window too short to be meaningful — leave state untouched so it
+            // keeps accumulating until a real sample can be taken.
+            return false;
+        }
+
+        let n = CpuSample::now();
+        let delta_ru = (n.user_secs - self.user_secs) + (n.sys_secs - self.sys_secs);
+
+        let efficiency = delta_ru / delta_wall;
+        let activate = 0f64.max(efficiency - self.previous) >= threshold;
+
+        debug!(
+            "Do I activate : {} -> {} = {} Activate: {}",
+            self.previous,
+            efficiency,
+            0f64.max(efficiency - self.previous),
+            activate
+        );
+        self.previous = efficiency;
+        self.user_secs = n.user_secs;
+        self.sys_secs = n.sys_secs;
+        self.wall = n.wall;
+
+        activate
+    }
+}
+
+// ── IoSample ──────────────────────────────────────────────────────────────────
+
+/// Snapshot of process-wide block I/O (bytes read + written) + wall clock.
+///
+/// Same activation protocol as [`CpuSample`], but the growth check in
+/// [`do_i_activate`](Self::do_i_activate) is *relative* rather than absolute:
+/// raw I/O throughput has no portable scale across storage devices, unlike a
+/// core count.
+pub struct IoSample {
+    wall: Instant,
+    bytes: u64,
+    previous_rate: f64,
+}
+
+impl IoSample {
+    pub fn now() -> Self {
+        Self {
+            wall: Instant::now(),
+            bytes: Self::read_bytes(),
+            previous_rate: 0.0,
+        }
+    }
+
+    /// Bytes actually submitted to the block layer (read + write), summed
+    /// process-wide. Returns 0 if unavailable — degrades gracefully to a
+    /// signal that never triggers activation (CPU-only heuristic).
+    #[cfg(target_os = "linux")]
+    fn read_bytes() -> u64 {
+        let Ok(io) = std::fs::read_to_string("/proc/self/io") else {
+            return 0;
+        };
+        io.lines()
+            .filter_map(|l| {
+                l.strip_prefix("read_bytes: ")
+                    .or_else(|| l.strip_prefix("write_bytes: "))
+            })
+            .filter_map(|v| v.trim().parse::<u64>().ok())
+            .sum()
+    }
+
+    #[cfg(target_os = "macos")]
+    fn read_bytes() -> u64 {
+        use libc::{RUSAGE_INFO_V4, getpid, proc_pid_rusage, rusage_info_v4};
+        let mut info: rusage_info_v4 = unsafe { std::mem::zeroed() };
+        let ret =
+            unsafe { proc_pid_rusage(getpid(), RUSAGE_INFO_V4, &mut info as *mut _ as *mut _) };
+        if ret != 0 {
+            return 0;
+        }
+        info.ri_diskio_bytesread + info.ri_diskio_byteswritten
+    }
+
+    #[cfg(not(any(target_os = "linux", target_os = "macos")))]
+    fn read_bytes() -> u64 {
+        0
+    }
+
+    /// Same protocol as [`CpuSample::do_i_activate`] (0.1 s minimum window,
+    /// state untouched on early return), but growth is measured relative to
+    /// the previous rate. `threshold` is a fraction, e.g. `0.2` for a 20 %
+    /// increase in throughput since the last real sample.
+    pub fn do_i_activate(&mut self, threshold: f64) -> bool {
+        let elapsed = self.wall.elapsed().as_secs_f64();
+        if elapsed < 0.1 {
+            return false;
+        }
+
+        let n = Self::read_bytes();
+        let rate = n.saturating_sub(self.bytes) as f64 / elapsed;
+        let activate = if self.previous_rate == 0.0 {
+            rate > 0.0 // bootstrap: any measured throughput is signal enough
+        } else {
+            (rate - self.previous_rate) / self.previous_rate >= threshold
+        };
+
+        debug!(
+            "Do I activate (I/O) : {} -> {} Activate: {}",
+            self.previous_rate, rate, activate
+        );
+        self.previous_rate = rate;
+        self.bytes = n;
+        self.wall = Instant::now();
+
+        activate
+    }
 }
 
 // ── public API ────────────────────────────────────────────────────────────────
@@ -259,7 +396,11 @@ impl Stage {
     pub fn start(label: impl Into<String>) -> Self {
         let label = label.into();
         info!(stage = %label, "started");
-        Self { label, wall: Instant::now(), ru: get_rusage() }
+        Self {
+            label,
+            wall: Instant::now(),
+            ru: get_rusage(),
+        }
     }
 
     pub fn stop(self) -> StageStats {
@@ -318,8 +459,11 @@ pub struct StageStats {
 impl StageStats {
     /// (user + sys) / wall — effective thread count utilisation.
     pub fn parallelism(&self) -> f64 {
-        if self.wall_secs > 1e-9 { (self.user_secs + self.sys_secs) / self.wall_secs }
+        if self.wall_secs > 1e-9 {
-        else { 0.0 }
+            (self.user_secs + self.sys_secs) / self.wall_secs
+        } else {
+            0.0
+        }
     }
 
     /// parallelism / n_cores — fraction of available CPU power used (0..1+).
@@ -335,11 +479,19 @@ pub struct Reporter {
 }
 
 impl Reporter {
-    pub fn new() -> Self { Self::default() }
+    pub fn new() -> Self {
-    pub fn push(&mut self, stats: StageStats) { self.stages.push(stats); }
+        Self::default()
-    pub fn stages(&self) -> &[StageStats] { &self.stages }
+    }
+    pub fn push(&mut self, stats: StageStats) {
+        self.stages.push(stats);
+    }
+    pub fn stages(&self) -> &[StageStats] {
+        &self.stages
+    }
     /// Print the summary to stderr.
-    pub fn print(&self) { eprint!("{self}"); }
+    pub fn print(&self) {
+        eprint!("{self}");
+    }
 }
 
 // ── diagnosis ─────────────────────────────────────────────────────────────────
@@ -387,26 +539,43 @@ fn diagnose(s: &StageStats, n_cores: usize) -> Diagnosis {
             )),
         };
     }
-    Diagnosis { tag: "—", detail: None }
+    Diagnosis {
+        tag: "—",
+        detail: None,
+    }
 }
 
 // ── display helpers ───────────────────────────────────────────────────────────
 
 fn fmt_secs(s: f64) -> String {
-    if s >= 100.0     { format!("{:.0}s",  s) }
+    if s >= 100.0 {
-    else if s >= 10.0 { format!("{:.1}s",  s) }
+        format!("{:.0}s", s)
-    else if s >= 1.0  { format!("{:.2}s",  s) }
+    } else if s >= 10.0 {
-    else              { format!("{:.0}ms", s * 1000.0) }
+        format!("{:.1}s", s)
+    } else if s >= 1.0 {
+        format!("{:.2}s", s)
+    } else {
+        format!("{:.0}ms", s * 1000.0)
+    }
 }
 
 fn fmt_bytes(b: u64) -> String {
-    if b >= 1 << 30      { format!("{:.1} GB", b as f64 / (1u64 << 30) as f64) }
+    if b >= 1 << 30 {
-    else if b >= 1 << 20 { format!("{:.0} MB", b as f64 / (1u64 << 20) as f64) }
+        format!("{:.1} GB", b as f64 / (1u64 << 30) as f64)
-    else                 { format!("{:.0} KB", b as f64 / 1024.0) }
+    } else if b >= 1 << 20 {
+        format!("{:.0} MB", b as f64 / (1u64 << 20) as f64)
+    } else {
+        format!("{:.0} KB", b as f64 / 1024.0)
+    }
 }
 
 fn fmt_efficiency(par: f64, n_cores: usize) -> String {
-    format!("{:.1}×/{} ({:.0}%)", par, n_cores, par / n_cores as f64 * 100.0)
+    format!(
+        "{:.1}×/{} ({:.0}%)",
+        par,
+        n_cores,
+        par / n_cores as f64 * 100.0
+    )
 }
 
 // ── Display ───────────────────────────────────────────────────────────────────
@@ -434,7 +603,11 @@ impl MemoryBudget {
     pub fn new(total: u64) -> Self {
         Self {
             total,
-            inner:   Mutex::new(BudgetInner { remaining: total, active: 0, peak_active: 0 }),
+            inner: Mutex::new(BudgetInner {
+                remaining: total,
+                active: 0,
+                peak_active: 0,
+            }),
             condvar: Condvar::new(),
         }
     }
@@ -459,24 +632,40 @@ impl MemoryBudget {
         self.condvar.notify_all();
     }
 
-    pub fn total(&self)       -> u64   { self.total }
+    pub fn total(&self) -> u64 {
-    pub fn active(&self)      -> usize { self.inner.lock().unwrap().active }
+        self.total
-    pub fn remaining(&self)   -> u64   { self.inner.lock().unwrap().remaining }
+    }
-    pub fn peak_active(&self) -> usize { self.inner.lock().unwrap().peak_active }
+    pub fn active(&self) -> usize {
+        self.inner.lock().unwrap().active
+    }
+    pub fn remaining(&self) -> u64 {
+        self.inner.lock().unwrap().remaining
+    }
+    pub fn peak_active(&self) -> usize {
+        self.inner.lock().unwrap().peak_active
+    }
 }
 
 // ── Display ───────────────────────────────────────────────────────────────────
 
 impl fmt::Display for Reporter {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        if self.stages.is_empty() { return Ok(()); }
+        if self.stages.is_empty() {
+            return Ok(());
+        }
 
         let n_cores = std::thread::available_parallelism()
             .map(|n| n.get())
             .unwrap_or(1);
 
         // column widths
-        let nw = self.stages.iter().map(|s| s.label.len()).max().unwrap_or(5).max(5);
+        let nw = self
+            .stages
+            .iter()
+            .map(|s| s.label.len())
+            .max()
+            .unwrap_or(5)
+            .max(5);
         // efficiency col: worst-case width for this run's n_cores value
         let ew = format!("{:.1}×/{} (100%)", 99.9f64, n_cores).len();
 
@@ -484,18 +673,21 @@ impl fmt::Display for Reporter {
         let sep = "─".repeat(sep_w);
 
         // header
-        writeln!(f, "{:<nw$}  {:>7}  {:>ew$}  {:>8}  status",
+        writeln!(
-            "stage", "wall", "efficiency", "peak RSS")?;
+            f,
+            "{:<nw$}  {:>7}  {:>ew$}  {:>8}  status",
+            "stage", "wall", "efficiency", "peak RSS"
+        )?;
         writeln!(f, "{sep}")?;
 
         // compute all diagnoses up front (needed for both table and footnotes)
-        let diagnoses: Vec<Diagnosis> = self.stages.iter()
+        let diagnoses: Vec<Diagnosis> = self.stages.iter().map(|s| diagnose(s, n_cores)).collect();
-            .map(|s| diagnose(s, n_cores))
-            .collect();
 
         // per-stage rows
         for (s, d) in self.stages.iter().zip(diagnoses.iter()) {
-            writeln!(f, "{:<nw$}  {:>7}  {:>ew$}  {:>8}  {}",
+            writeln!(
+                f,
+                "{:<nw$}  {:>7}  {:>ew$}  {:>8}  {}",
                 s.label,
                 fmt_secs(s.wall_secs),
                 fmt_efficiency(s.parallelism(), n_cores),
@@ -508,11 +700,18 @@ impl fmt::Display for Reporter {
         let tw = self.stages.iter().map(|s| s.wall_secs).sum::<f64>();
         let tu = self.stages.iter().map(|s| s.user_secs).sum::<f64>();
         let ts = self.stages.iter().map(|s| s.sys_secs).sum::<f64>();
-        let trss = self.stages.iter().map(|s| s.max_rss_bytes).max().unwrap_or(0);
+        let trss = self
+            .stages
+            .iter()
+            .map(|s| s.max_rss_bytes)
+            .max()
+            .unwrap_or(0);
         let tpar = if tw > 1e-9 { (tu + ts) / tw } else { 0.0 };
 
         writeln!(f, "{sep}")?;
-        writeln!(f, "{:<nw$}  {:>7}  {:>ew$}  {:>8}",
+        writeln!(
+            f,
+            "{:<nw$}  {:>7}  {:>ew$}  {:>8}",
             "TOTAL",
             fmt_secs(tw),
             fmt_efficiency(tpar, n_cores),
@@ -520,7 +719,9 @@ impl fmt::Display for Reporter {
         )?;
 
         // bottleneck footnotes (only if at least one anomaly detected)
-        let bottlenecks: Vec<(&str, &str)> = self.stages.iter()
+        let bottlenecks: Vec<(&str, &str)> = self
+            .stages
+            .iter()
             .zip(diagnoses.iter())
             .filter_map(|(s, d)| d.detail.as_deref().map(|det| (s.label.as_str(), det)))
             .collect();