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Stop BRouter contention kills under rapid editing

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When a user rapidly moves waypoints in the Planner, BRouter's
thread-priority watchdog kills older in-flight requests to free a thread
for newer ones, surfacing to the user as "operation killed by
thread-priority-watchdog" errors.

Two fixes:

1. Bump the BRouter thread pool on the dedicated host from 4 to 16.
   `BROUTER_THREADS` is now a Dockerfile ENV (default 4 for
   flagship/CI/dev) overridden to 16 in `infrastructure/brouter-host/`.
   The host has 32 GB of RAM and idle cores; 4 threads was a flagship-era
   constraint that no longer applies.

2. Cancel the previous in-flight `/api/route` request when a new one
   starts. `use-routing.ts` now keeps an `AbortController` in a ref,
   aborts it at the top of each `computeRoute`, and bails quietly on
   `AbortError` so the newer call drives state.

Together these eliminate both the "real" contention (at the BRouter
level) and the wasted work (BRouter computing a route the client no
longer cares about).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
Ullrich Schäfer 2026-04-24 17:43:15 +02:00
parent 05b72e9114
commit f283401076
3 changed files with 29 additions and 4 deletions
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18
apps/planner/app/lib/use-routing.ts
View file

@ -51,6 +51,10 @@ export function useRouting(yjs: YjsState | null, sessionId: string) {
const debounceTimer = useRef<ReturnType<typeof setTimeout>>(undefined);
const lastGoodWaypointsRef = useRef<WaypointData[] | null>(null);
const restoringRef = useRef(false);
// Cancels the in-flight /api/route call when a newer one starts. Without
// this, rapid edits pile up on BRouter's thread pool and older requests
// get killed by its contention watchdog, surfacing as spurious errors.
const inflightAbortRef = useRef<AbortController | null>(null);
// Host election via Yjs awareness
useEffect(() => {
@ -85,6 +89,9 @@ export function useRouting(yjs: YjsState | null, sessionId: string) {
const snapshotBeforeCompute = getWaypointsFromYjs(yjs.waypoints);
setComputing(true);
inflightAbortRef.current?.abort();
const controller = new AbortController();
inflightAbortRef.current = controller;
try {
const response = await fetch("/api/route", {
method: "POST",
@ -95,6 +102,7 @@ export function useRouting(yjs: YjsState | null, sessionId: string) {
noGoAreas: noGoAreas.length > 0 ? noGoAreas : undefined,
sessionId,
}),
signal: controller.signal,
});
if (response.status === 429) {
@ -146,11 +154,17 @@ export function useRouting(yjs: YjsState | null, sessionId: string) {
yjs.routeData.set("bikeroutes", JSON.stringify(enriched.bikeroutes));
}
});
} catch {
} catch (err) {
// A superseding request aborted this one — leave state alone so
// the newer call's result becomes authoritative.
if ((err as Error)?.name === "AbortError") return;
setRouteError("failed");
restoreWaypoints(yjs, lastGoodWaypointsRef.current ?? snapshotBeforeCompute, restoringRef);
} finally {
setComputing(false);
if (inflightAbortRef.current === controller) {
inflightAbortRef.current = null;
setComputing(false);
}
}
},
[yjs, isHost],