chore: update KPN to the wedging-audit fixes

Twenty commits, of which the one that matters for this repo is the filter
and router losslessness. FilterNode and RouterNode were the last nodes on a
data path still using the throwing push() and swallowing the exception, so
`decimate` — which passes EOF by predicate — discarded that token whenever
its output was full. Which it reliably is: the embedder is the slowest node
in the chain. Nothing downstream ever received EOF, `done` was never set,
and the run had to be killed. That is the wedge.

The rest, in rough order of how much they affect a run here:

- A sentinel could be delivered ahead of a value still queued behind it,
  losing that value to any consumer treating EOF as a hard stop.
- Two fire_once invocations for one node could overlap, which breaks the
  one-slot park: a parked value can be overwritten with no drop recorded.
- A node's push/space callbacks were written while a running neighbour read
  them — ten ThreadSanitizer races, and the root cause of the startup lost
  wake that AR-004 records as closed by a level-triggered re-check.
- shutdown() polled every channel in the graph with no deadline, and could
  fail to terminate outright on an index underflow in the fill calculation.
- Submitting to a stopped pool indexed a cleared vector: a segfault, which
  reproduced 12 runs in 20 once sources stopped before their consumers.
- stop() returned while a firing was still touching the node's members.
- Idle pool workers burned ~6.5 cores while one task ran (1991 ms of CPU
  against 0.4 ms). Latent here, since every node owns a private one-thread
  pool, but not for anything using a shared one.

Two consequences worth holding onto. `decimate` is now a backpressure point
rather than a relief valve, so the source throttles to the face branch
instead of quietly thinning it — the intended behaviour, but it changes the
shape of a loaded run and has not been benchmarked. And a channel now
carries at most one undelivered sentinel; a second is refused and reported
rather than silently overwriting the first.

Verified: KPN 148/148 with ThreadSanitizer clean across six runs, this repo
138/138 with every target building warning-free against the new headers.

TRACES: AR-004 | SR-002

This commit is contained in:

dtourolle

2026-08-05 18:26:11 +02:00

parent 90b44e0975

commit 1141172b04

1 changed files with 1 additions and 1 deletions

external/KPN

Vendored

+1 -1

Submodule external/KPN updated: 454f72c167...27f884496d