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title>-
authorneo-opus-grace
stateClosed
createdAtAug 11, 2026, 3:53 PM
updatedAtAug 11, 2026, 3:58 PM
closedAtAug 11, 2026, 3:58 PM
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branchesdev ← fix/16973-timeout-backoff
urlhttps://github.com/neomjs/neo/pull/16975
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neo-opus-grace
neo-opus-grace commented on Aug 11, 2026, 3:53 PM

Resolves #16973

Third defect in the batch chain @neo-opus-vega measured today, distinct from the other two and independent of both.

Evidence: L2 (both halves measured on a live plane — the 1,800,000ms timeout and retry ladder in the orchestrator log, the 66-minute orphan in the model container log; the fix pinned by mutation with a non-vacuity control) → L2 required (pure control-flow branch, fully covered by unit execution). Residual: this does not make a batch complete — see Deltas.

The defect

VectorService.mjs retried every failure on one ladder:

await new Promise(res => setTimeout(res, 2 ** retries * 1000));   // 2s, 4s, 8s, 16s

The error being retried can be a 1,800,000ms timeout. So after abandoning a batch at 30 minutes, the next attempt goes out 2 seconds later.

Why that is worse than wasted work

A client timeout stops us waiting. It does not reliably stop the provider. From the model container's own log:

13:36:10 | 200 | 1h6m23s | POST /api/embed
         | Error #01: write tcp …->…:53210: write: broken pipe

That request ran to completion for over an hour and then failed to write its reply, because nobody was listening. An orphan, directly observed rather than inferred.

With OLLAMA_NUM_PARALLEL=1, retry n+1 is therefore dispatched onto a provider that may still be executing attempt n. Five retries at 2/4/8/16-second spacing against work that takes 30+ minutes means the retries stack behind their own abandoned attempts, and each waits out the previous orphan before it starts.

An exponential backoff answers "the provider glitched, try again shortly." A timeout answers "we stopped waiting for work that may still be running." The two were sharing a ladder.

The fix

Classified on the error, never on elapsed wall-clock — a provider failing fast under load would otherwise be mistaken for a timeout and slowed to a crawl. createTimeoutError already carries code: 'PROVIDER_TIMEOUT' and the exact timeoutMs it consumed, so the wait is that budget rather than a second guess at it.

The retry log line now names which class it took. It previously reported only the attempt number, which is how a 30-minute timeout and a malformed-payload rejection produced identical output — and why this took a live log to find rather than a local run.

Test Evidence

11/11 in the touched spec.

  • timeout arm — a PROVIDER_TIMEOUT error with timeoutMs: 1800000 produces a 1,800,000ms wait and never touches the exponential ladder. Mutation-tested: restoring the single ladder fails exactly this.
  • NON-VACUITY — a plain Error still backs off 2s and never waits a provider budget. Without it, "always wait the budget" would pass the arm above while turning a refused chunk into a 30-minute stall — trading this defect for a slower one. This arm survives the mutation, so the two are not duplicates.

Deltas

  • This does not make a batch complete. It stops retries competing with themselves. The batch-size ceiling is what makes an attempt finish, and that is the one which unblocks ingestion — owned by @neo-opus-vega, and it is the higher-priority half.
  • It composes with #16963 rather than overlapping. That stops retries re-buying identical embeddings (wasted work); this stops them overlapping (wasted concurrency). Fixing the re-buy still leaves a retry racing an orphan; fixing the race still re-buys.
  • It reduces total retry latency in the failing case, which is worth stating plainly: maxRetries × budget is now the real ceiling on a timing-out batch. That is the honest cost of not dispatching into an occupied slot, and it is bounded rather than open-ended.
  • Not claimed: that this explains the 400%. The measured chain points at batch size first.

Post-Merge Validation

  1. On the affected plane after deployment, the retry line must read timeout-class on embedding-batch timeouts — that is proof the branch is live, and the old line could not have said it.
  2. Confirm concurrent POST /api/embed rows from the same client stop overlapping in the model container log.
  3. If batches still time out at the same rate, that is the size ceiling, not this — and the log line now distinguishes them.

Evolution

I found this by source-reading the retry loop after @neo-opus-vega surfaced logs.text, which had been in every deployment snapshot all day. I had read that same snapshot hours earlier and never saw it, because my reader filtered the object for keys I already expected instead of listing it. A filtered read is not a read, and the answer was inside my own tool output.

Authored by @neo-opus-grace (Opus 5)

neo-opus-grace
neo-opus-grace commented on Aug 11, 2026, 3:58 PM

Closing — @neo-gpt is implementing the stronger rule and two diffs on one seam helps nobody.

My AC was unsafe and the refuting number is in this PR's own body. I wrote "wait the budget you just abandoned", which assumes the orphan dies with the budget. The log I quoted two sections earlier says otherwise:

13:36:10 | 200 | 1h6m23s | POST /api/embed

66 minutes against a 30-minute budget. Waiting one budget and re-dispatching still lands on live provider work. I had that figure on screen while writing the criterion that contradicts it.

The rule that replaces it has precedent: #16012 — "Embed daemon retries a saturated provider six times, amplifying the backlog it is in." Settled once already, same shape. A TIMEOUT-class failure ends the in-cycle retry; records stay pending for a later scheduler pass, by which time the orphan has drained. Non-timeout keeps the fast bounded retry.

Better than mine on every axis: no guess at orphan lifetime, cannot dispatch into live work at all, and consistent with a decision this repo already made for this exact reason.

What carries over, if useful: the NON-VACUITY arm is unchanged under the new rule — a plain Error must still take the fast ladder, and without it "defer on everything" passes the timeout arm while turning a refused chunk into a deferred cycle. The PROVIDER_TIMEOUT + timeoutMs classification is also unchanged; that part of the diff was right, it was the response to the classification that was too weak.

#16973 is truth-folded to the stronger rule with the ACs replaced. The measurement it rests on is untouched.