Introduce concurrency-bounded parallel processing for index cache layers

Implement an `obipipeline::Throttle` with an RAII guard to acquire and release concurrency slots. Expose new bounded parallel methods on `IndexCache` to process cached layers with a configurable cap. Refactor downstream aggregation logic to use single-pass parallel map-reduce instead of manual collect-map-reduce sequences, enforcing a maximum of 8 concurrent layer scans to bound memory usage.
This commit is contained in:
Eric Coissac
2026-08-28 20:20:12 +02:00
parent 9dee6dcd08
commit d084396aba
6 changed files with 211 additions and 62 deletions
+80 -40
View File
@@ -2,16 +2,17 @@
//! (summing per-layer partials into one global partial) and the final
//! distance calculation are both phylogenetic domain logic, so both live
//! here, not in `obikidxcache` (which only ever hands out already-opened
//! `KmerLayer`s via `IndexCache::iter()` — plain exposition, no
//! computation of its own).
//! `KmerLayer`s, via plain exposition — `IndexCache::iter()` — or bounded
//! parallel map-reduce over them — `IndexCache::par_map_reduce()` — neither
//! of which computes anything phylo-specific itself).
//!
//! [`AggregatedCount`]/[`AggregatedBit`] exist purely to "hang"
//! `obicompactvec`'s `CountPartials`/`BitPartials` traits on a borrowed
//! collection of `KmerLayer`s, so their already-written finalisation
//! methods (`bray_dist_matrix`, `jaccard_dist_matrix`, ...) can be reused
//! as-is instead of re-derived here — see `KmerLayer`'s own
//! `ColumnWeights`/`CountPartials`/`BitPartials` impls (`obikindex`) for
//! the per-layer primitives these sum.
//! `obicompactvec`'s `CountPartials`/`BitPartials` traits on a bounded
//! parallel reduction over `IndexCache`'s layers, so their already-written
//! finalisation methods (`bray_dist_matrix`, `jaccard_dist_matrix`, ...) can
//! be reused as-is instead of re-derived here — see `KmerLayer`'s own
//! `ColumnWeights`/`CountPartials`/`BitPartials` impls (`obikindex`) for the
//! per-layer primitives these sum.
use ndarray::{Array1, Array2};
use obicompactvec::{BitPartials, ColumnWeights, CountPartials};
@@ -64,77 +65,118 @@ impl DistanceMetric {
}
}
// ── Aggregators — sum every cached layer's own partials into one global
// partial, then hand the result off to `CountPartials`/`BitPartials`'s own
// provided finalisation methods.
// ── Aggregators — bounded parallel reduction of every cached layer's own
// partial (of the wanted content kind) into one global partial, then handed
// off to `CountPartials`/`BitPartials`'s own provided finalisation methods.
// Layers of the *other* content kind contribute their zero element, same
// as a layer that's simply absent — cheaper than pre-collecting a filtered
// `Vec` first, since `IndexCache::par_map_reduce` never allocates one.
fn sum_array1(n: usize, items: impl Iterator<Item = Array1<u64>>) -> Array1<u64> {
items.fold(Array1::zeros(n), |acc, x| acc + x)
}
fn sum_array2_u64(n: usize, items: impl Iterator<Item = Array2<u64>>) -> Array2<u64> {
items.fold(Array2::zeros((n, n)), |acc, x| acc + x)
}
fn sum_array2_f64(n: usize, items: impl Iterator<Item = Array2<f64>>) -> Array2<f64> {
items.fold(Array2::zeros((n, n)), |acc, x| acc + x)
}
/// Layers scanned at once per `par_map_reduce` call — bounds resident
/// memory (each layer's own partial-computation working set), independent
/// of how many `rayon` threads exist. See `IndexCache::par_map_reduce`'s
/// own docs for why this is a separate knob from thread count.
const MAX_CONCURRENT_LAYERS: usize = 8;
struct AggregatedCount<'a> {
cache: &'a IndexCache,
n_genomes: usize,
layers: Vec<&'a KmerLayer>,
}
impl AggregatedCount<'_> {
fn reduce<T: Send>(
&self,
identity: impl Fn() -> T + Sync,
per_layer: impl Fn(&KmerLayer) -> T + Sync,
combine: impl Fn(T, T) -> T + Sync,
) -> T {
self.cache.par_map_reduce(
MAX_CONCURRENT_LAYERS,
&identity,
|layer| if layer.content() == LayerContent::Count { per_layer(layer) } else { identity() },
&combine,
)
}
}
impl ColumnWeights for AggregatedCount<'_> {
fn col_weights(&self) -> Array1<u64> {
sum_array1(self.n_genomes, self.layers.iter().map(|l| l.col_weights()))
let n = self.n_genomes;
self.reduce(|| Array1::zeros(n), |l| l.col_weights(), |a, b| a + b)
}
}
impl CountPartials for AggregatedCount<'_> {
fn partial_bray(&self) -> Array2<u64> {
sum_array2_u64(self.n_genomes, self.layers.iter().map(|l| l.partial_bray()))
let n = self.n_genomes;
self.reduce(|| Array2::zeros((n, n)), |l| l.partial_bray(), |a, b| a + b)
}
fn partial_euclidean(&self) -> Array2<f64> {
sum_array2_f64(self.n_genomes, self.layers.iter().map(|l| l.partial_euclidean()))
let n = self.n_genomes;
self.reduce(|| Array2::zeros((n, n)), |l| l.partial_euclidean(), |a, b| a + b)
}
fn partial_threshold_jaccard(&self, threshold: u32) -> (Array2<u64>, Array2<u64>) {
let n = self.n_genomes;
self.layers.iter().map(|l| l.partial_threshold_jaccard(threshold)).fold(
(Array2::zeros((n, n)), Array2::zeros((n, n))),
|(inter, union), (i, u)| (inter + i, union + u),
self.reduce(
|| (Array2::zeros((n, n)), Array2::zeros((n, n))),
|l| l.partial_threshold_jaccard(threshold),
|(ia, ua), (ib, ub)| (ia + ib, ua + ub),
)
}
fn partial_relfreq_bray(&self, global: &Array1<u64>) -> Array2<f64> {
sum_array2_f64(self.n_genomes, self.layers.iter().map(|l| l.partial_relfreq_bray(global)))
let n = self.n_genomes;
self.reduce(|| Array2::zeros((n, n)), |l| l.partial_relfreq_bray(global), |a, b| a + b)
}
fn partial_relfreq_euclidean(&self, global: &Array1<u64>) -> Array2<f64> {
sum_array2_f64(self.n_genomes, self.layers.iter().map(|l| l.partial_relfreq_euclidean(global)))
let n = self.n_genomes;
self.reduce(|| Array2::zeros((n, n)), |l| l.partial_relfreq_euclidean(global), |a, b| a + b)
}
fn partial_hellinger(&self, global: &Array1<u64>) -> Array2<f64> {
sum_array2_f64(self.n_genomes, self.layers.iter().map(|l| l.partial_hellinger(global)))
let n = self.n_genomes;
self.reduce(|| Array2::zeros((n, n)), |l| l.partial_hellinger(global), |a, b| a + b)
}
}
struct AggregatedBit<'a> {
cache: &'a IndexCache,
n_genomes: usize,
layers: Vec<&'a KmerLayer>,
}
impl AggregatedBit<'_> {
fn reduce<T: Send>(
&self,
identity: impl Fn() -> T + Sync,
per_layer: impl Fn(&KmerLayer) -> T + Sync,
combine: impl Fn(T, T) -> T + Sync,
) -> T {
self.cache.par_map_reduce(
MAX_CONCURRENT_LAYERS,
&identity,
|layer| if layer.content() == LayerContent::Presence { per_layer(layer) } else { identity() },
&combine,
)
}
}
impl ColumnWeights for AggregatedBit<'_> {
fn col_weights(&self) -> Array1<u64> {
sum_array1(self.n_genomes, self.layers.iter().map(|l| l.col_weights()))
let n = self.n_genomes;
self.reduce(|| Array1::zeros(n), |l| l.col_weights(), |a, b| a + b)
}
}
impl BitPartials for AggregatedBit<'_> {
fn partial_jaccard(&self) -> (Array2<u64>, Array2<u64>) {
let n = self.n_genomes;
self.layers.iter().map(|l| l.partial_jaccard()).fold(
(Array2::zeros((n, n)), Array2::zeros((n, n))),
|(inter, union), (i, u)| (inter + i, union + u),
self.reduce(
|| (Array2::zeros((n, n)), Array2::zeros((n, n))),
|l| l.partial_jaccard(),
|(ia, ua), (ib, ub)| (ia + ib, ua + ub),
)
}
fn partial_hamming(&self) -> Array2<u64> {
sum_array2_u64(self.n_genomes, self.layers.iter().map(|l| l.partial_hamming()))
let n = self.n_genomes;
self.reduce(|| Array2::zeros((n, n)), |l| l.partial_hamming(), |a, b| a + b)
}
}
@@ -167,8 +209,7 @@ impl Metrics for IndexCache {
let kmer_size = self.meta().config().kmer_size;
if use_counts {
let layers: Vec<&KmerLayer> = self.iter().filter(|l| l.content() == LayerContent::Count).collect();
let agg = AggregatedCount { n_genomes, layers };
let agg = AggregatedCount { cache: self, n_genomes };
let matrix = match metric {
DistanceMetric::BrayCurtis => agg.bray_dist_matrix(),
@@ -195,8 +236,7 @@ impl Metrics for IndexCache {
Ok(DistanceOutput { matrix, shared_kmers: shared })
} else {
let layers: Vec<&KmerLayer> = self.iter().filter(|l| l.content() == LayerContent::Presence).collect();
let agg = AggregatedBit { n_genomes, layers };
let agg = AggregatedBit { cache: self, n_genomes };
let matrix = match metric {
DistanceMetric::Jaccard => agg.jaccard_dist_matrix(),