[e2e] Probe: raise 1s workflow sleeps to 6s by shalabhc · Pull Request #3744 · vercel/workflow

shalabhc · 2026-08-22T01:18:17Z

Not for merge — diagnostic probe

Raises every sleep('1s') in the e2e workflows to sleep('6s') (16 in the TS workbench, 1 in Python).

What this actually tests (revised)

Sleep does not wait in-process. createSleep registers the wait and throws WorkflowSuspension; the invocation exits. The suspension handler computes delayMs = Math.max(1000, resumeAt - now), timeoutSeconds = ceil(delayMs/1000) and enqueues a wait-continuation message. Resume happens only when that message is delivered.

getWaitContinuationDispatch picks the continuation's idempotency key by remaining time, and the branch flips at NEAR_ELAPSED_WAIT_THRESHOLD_SECONDS = 2:

sleep	timeoutSeconds	idempotency key
`1s` (today)	1	`correlationId:floor(now/1000)` — second-bucketed, refreshes
`6s` (this PR)	6	bare `correlationId` — one key, forever

So this probe does not just make waits longer, it moves every wait from the bucketed key onto the bare key. That matters, because the bare-key branch carries a documented stall:

once a key has been used, a later enqueue under the same key is silently dropped. Any situation where a continuation is delivered while its wait is still pending therefore needs a fresh key for the re-enqueue, or the wait's timer is lost and the run stalls until unrelated traffic happens to wake it.

Host clock skew beyond the near-elapsed threshold could in principle deliver such a continuation early enough to re-observe its wait and lose the re-enqueue to the burnt key; the threshold is the skew tolerance we accept.

That is exactly the failure signature on main: wait_created with no wait_completed, Status: running, no errors, no handler-failure logs, and normal queue metrics — because a deduped enqueue is correct behaviour, not an error.

Reading the result

More stalls than main → implicates the bare-correlationId continuation key; the near-elapsed bucketing is what has been masking it.
Fewer/no stalls → the burnt key is not the mechanism and the loss is in delivery generally.

Either outcome is informative. A red run here is a signal, not a regression.

Confound to control next

Duration and key strategy move together in this PR. WORKFLOW_NEAR_ELAPSED_WAIT_THRESHOLD_SECONDS is an env override — setting it above the sleep duration keeps 6s waits on the bucketed key, isolating key strategy from duration. Worth a second run.

Also raises five outputStream test timeouts 60s → 120s

outputStreamWorkflow and outputStreamInsideStepWorkflow have 5 sleeps each, so they go from ~5s to ~30s of sleeping. Against the old 60s timeout a merely-slow run would time out and be indistinguishable from a stall. 120s keeps a timeout meaningful: it means the run hung, not that it was slow.

Co-Authored-By: shalabhc <shalabh.chaturvedi@vercel.com>

changeset-bot · 2026-08-22T01:18:22Z

⚠️ No Changeset found

Latest commit: 6154e23

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vercel · 2026-08-22T01:18:23Z

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview, v0	Aug 22, 2026 1:21am
example-nextjs-workflow-webpack	Ready	Preview, v0	Aug 22, 2026 1:21am
example-workflow	Ready	Preview, v0	Aug 22, 2026 1:21am
workbench-astro-workflow	Ready	Preview, v0	Aug 22, 2026 1:21am
workbench-express-workflow	Ready	Preview, v0	Aug 22, 2026 1:21am
workbench-fastify-workflow	Ready	Preview, v0	Aug 22, 2026 1:21am
workbench-hono-workflow	Ready	Preview, v0	Aug 22, 2026 1:21am
workbench-nestjs-workflow	Ready	Preview, v0	Aug 22, 2026 1:21am
workbench-nitro-workflow	Ready	Preview, v0	Aug 22, 2026 1:21am
workbench-nuxt-workflow	Ready	Preview, v0	Aug 22, 2026 1:21am
workbench-python-workflow	Ready	Preview, v0	Aug 22, 2026 1:21am
workbench-sveltekit-workflow	Ready	Preview, v0	Aug 22, 2026 1:21am
workbench-tanstack-start-workflow	Ready	Preview, v0	Aug 22, 2026 1:21am
workbench-vite-workflow	Ready	Preview, v0	Aug 22, 2026 1:21am
workflow-docs	Ready	Preview, v0	Aug 22, 2026 1:21am
workflow-swc-playground	Ready	Preview, v0	Aug 22, 2026 1:21am
workflow-tarballs	Ready	Preview, v0	Aug 22, 2026 1:21am
workflow-web	Error	v0	Aug 22, 2026 1:21am

github-actions · 2026-08-22T01:18:31Z

🧪 E2E Test Results

❌ Some tests failed

❌ Failed E2E Tests

▲ Vercel Production (8 failed)

python-node (8 failed):

promiseAllWorkflow | wrun_41M0KGVYRR0GX79J7FN0EAR20H | 🔍 observability
sleepingWorkflow | wrun_41M0KGWKEK0GWB6ZM7M2H07NQQ | 🔍 observability
parallelSleepWorkflow | wrun_41M0KGWNHW0GNRAB4XB4EEBS32 | 🔍 observability
nullByteWorkflow | wrun_41M0KGX0750GVMNZKR4TDBA8RM | 🔍 observability
cancelRun - cancelling a running workflow | wrun_41M0KH26AA0GJDQHZ4FC9AF7TT | 🔍 observability
cancelRun via CLI - cancelling a running workflow | wrun_41M0KH26P90GP6VZRBDF277VF7 | 🔍 observability
sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0KH2F3R0GQ03V2A0JKQ79C0 | 🔍 observability
resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0KH30700GP8DGARC9B1XPWR | 🔍 observability

💻 Local Development (1 failed)

tanstack-start-quickjs (1 failed):

sleepWinsRaceWorkflow | wrun_41M0KGWNYS0GHXRX1EN5DXX759

🌐 Cross-language Conformance (9 failed)

python (9 failed):

deploymentId: 'latest' is a no-op in non-Vercel worlds | wrun_01M0KH5K4QMMNAHCSTYE2F75KW
promiseAllWorkflow | wrun_41M0KGVYRR0GX79J7FN0EAR20H
sleepingWorkflow | wrun_41M0KGWKEK0GWB6ZM7M2H07NQQ
parallelSleepWorkflow | wrun_41M0KGWNHW0GNRAB4XB4EEBS32
nullByteWorkflow | wrun_41M0KGX0750GVMNZKR4TDBA8RM
cancelRun - cancelling a running workflow | wrun_41M0KH26AA0GJDQHZ4FC9AF7TT
cancelRun via CLI - cancelling a running workflow | wrun_41M0KH26P90GP6VZRBDF277VF7
sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0KH2F3R0GQ03V2A0JKQ79C0
resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0KH30700GP8DGARC9B1XPWR

⚠️ Flaky E2E Tests (passed on retry)

These tests failed at least once and passed on a retry. A recurring entry here is a real race worth investigating.

21 flaky tests

abortHookOrderingWorkflow [hook-first-abort-first]: hook.then → addEventListener → abort() → resumeHook (nuxt)
abortHookOrderingWorkflow [listener-first-abort-first]: addEventListener → hook.then → abort() → resumeHook (express)
abortHookOrderingWorkflow [listener-first-abort-first]: addEventListener → hook.then → abort() → resumeHook (tanstack-start)
abortHookOrderingWorkflow [listener-first-hook-first]: addEventListener → hook.then → resumeHook → abort() (example)
abortThrowIfAbortedWorkflow: throwIfAborted causes FatalError, no retries (vite)
abortVoidSleepTimeoutWorkflow: documented void sleep().then(abort) pattern works (fastify)
cancelRun via CLI - cancelling a running workflow (hono)
cancelRun via CLI - cancelling a running workflow (nuxt)
deploymentId: 'latest' is a no-op in non-Vercel worlds (express)
getTailIndex returns correct index after stream completes (astro)
health check (CLI) - workflow health command reports healthy endpoints (nextjs-webpack)
hookDisposeTestWorkflow - hook token reuse after explicit disposal while workflow still running (tanstack-start)
no startIndex (reads all chunks) (astro)
no startIndex (reads all chunks) (express)
no startIndex (reads all chunks) (nest)
positive startIndex (skips first chunk) (fastify)
positive startIndex (skips first chunk) (sveltekit)
RetryableError respects custom retryAfter delay (nextjs-webpack)
sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (tanstack-start)
sleepWinsRaceWorkflow (tanstack-start)
utf8StreamWorkflow (nextjs-turbopack)

🛠 Infra Events (absorbed by the harness)

Platform anomalies the e2e harness detected and worked around (e.g. a run the queue never picked up, replaced by a fresh run). Clustered timestamps indicate a backend blip; a steady drip indicates a platform issue worth escalating.

33 infra events

cold-start-warmup · suite warmup (python) · at 01:21:35Z · abandoned wrun_41M0KGTGGS0GV9Z4BE5RT2558T · (+7 more)
run-pickup-stall · nullByteWorkflow (python) · at 01:21:51Z · abandoned wrun_41M0KGY5CR0GGW8PFRKSHYG2K4
run-pickup-stall · sleepingWorkflow (python) · at 01:21:51Z · abandoned wrun_41M0KGY5CK0GQBGNK7C4BQBASM
run-pickup-stall · promiseAllWorkflow (python) · at 01:21:51Z · abandoned wrun_41M0KGY5CE0GM235DCF4A2PNN0
run-pickup-stall · parallelSleepWorkflow (python) · at 01:21:51Z · abandoned wrun_41M0KGY5CK0GQBGNK7C4BQBASN
run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 01:21:52Z · abandoned wrun_41M0KGY5Y50GSJ79Z1D4WFQ6G9
run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 01:22:25Z · abandoned wrun_41M0KGZ6KX0GYP5H2ZWW97FGPN
run-pickup-stall · sleepingWorkflow (python) · at 01:22:52Z · abandoned wrun_41M0KH00V50GYKKKZCJ758TNP9
run-pickup-stall · nullByteWorkflow (python) · at 01:22:52Z · abandoned wrun_41M0KH012A0GPSR7YSYK4N988V
run-pickup-stall · promiseAllWorkflow (python) · at 01:22:52Z · abandoned wrun_41M0KH00XR0GK3CM6TZEK2C3ER
run-pickup-stall · parallelSleepWorkflow (python) · at 01:22:52Z · abandoned wrun_41M0KH014T0GPKCBBT6F339D35
cold-start-warmup · suite warmup (tanstack-start) · at 01:23:20Z · abandoned wrun_01M0KH0HADS5APA07STTY47FV2
run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 01:23:43Z · abandoned wrun_41M0KH06QY0GZDR0JXX5H40ZG2
cold-start-warmup · suite warmup (python) · at 01:24:23Z · abandoned wrun_01M0KGZMPRN6XFKM4MJRQKT83S · (+7 more)
run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 01:24:38Z · abandoned wrun_01M0KH39VEQMVK73FSET9T38HC
run-pickup-stall · promiseAllWorkflow (python) · at 01:24:38Z · abandoned wrun_01M0KH39VFEWA1QVREYS2X3KHA
run-pickup-stall · nullByteWorkflow (python) · at 01:24:38Z · abandoned wrun_01M0KH39VRFVFGZE7C5PB7230M
run-pickup-stall · parallelSleepWorkflow (python) · at 01:24:38Z · abandoned wrun_01M0KH39VPVW81BNDKBEHVB494
run-pickup-stall · sleepingWorkflow (python) · at 01:24:38Z · abandoned wrun_01M0KH39VMEYKYX28ZP4EXV4YF
run-pickup-stall · abortHookOrderingWorkflow [listener-first-abort-first]: addEventListener → hook.then → abort() → resumeHook (tanstack-start) · at 01:25:17Z · abandoned wrun_41M0KH4E650GGCDCN6MK767N2S
run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 01:25:24Z · abandoned wrun_41M0KH2RQR0GGWGV9MGV52A4RG
run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 01:25:25Z · abandoned wrun_41M0KH2YMF0GH6C37G2PBG2HYQ
run-pickup-stall · sleepingWorkflow (python) · at 01:25:38Z · abandoned wrun_01M0KH54FCV8TAAHTYZBK24A6A
run-pickup-stall · promiseAllWorkflow (python) · at 01:25:38Z · abandoned wrun_01M0KH54F8H2TSH1AN2EQF686P
run-pickup-stall · parallelSleepWorkflow (python) · at 01:25:38Z · abandoned wrun_01M0KH54FE6D9W69RWFDK4EG5C
run-pickup-stall · nullByteWorkflow (python) · at 01:25:38Z · abandoned wrun_01M0KH54FG47VYZZDV35DMJH6F
run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 01:25:38Z · abandoned wrun_01M0KH54FAT2JGYR8W7808TF1E
run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 01:26:38Z · abandoned wrun_01M0KH6Z2XZ50YNHS6J7SY07DT
run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 01:26:38Z · abandoned wrun_01M0KH6Z3097QDQFDSDQS8EAFZ
run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 01:26:38Z · abandoned wrun_01M0KH6Z37Q2KN7PCE8VJXX8SF
run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 01:27:08Z · abandoned wrun_01M0KH7WEBJFDV14W4P9HSFEA7
run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 01:27:08Z · abandoned wrun_01M0KH7WEA0K50ZD9P1P43X580
run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 01:27:38Z · abandoned wrun_01M0KH8SPAK8YEAM58Q8NTNWAQ

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
❌ ▲ Vercel Production	3570	8	742	4320
❌ 💻 Local Development	3921	1	558	4480
✅ 📦 Local Production	3922	0	558	4480
✅ 🐘 Local Postgres	3922	0	558	4480
✅ 🪟 Windows	320	0	0	320
❌ 🌐 Cross-language Conformance	0	9	132	141
✅ vercel-http-transport	817	0	143	960
✅ vercel-multi-region	27	0	0	27
✅ vercel-ws-transport	553	0	87	640
Total	17052	18	2778	19848

Details by Category

❌ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro-node	132	0	28
✅ astro-quickjs	132	0	28
✅ example-node	132	0	28
✅ example-quickjs	132	0	28
✅ express-node	132	0	28
✅ express-quickjs	132	0	28
✅ fastify-node	132	0	28
✅ fastify-quickjs	132	0	28
✅ hono-node	132	0	28
✅ hono-quickjs	132	0	28
✅ nest-node	132	0	28
✅ nest-quickjs	132	0	28
✅ nextjs-turbopack-node	157	0	3
✅ nextjs-turbopack-quickjs	157	0	3
✅ nextjs-webpack-node	157	0	3
✅ nextjs-webpack-quickjs	157	0	3
✅ nitro-node	132	0	28
✅ nitro-quickjs	132	0	28
✅ nuxt-node	132	0	28
✅ nuxt-quickjs	132	0	28
❌ python-node	0	8	152
✅ sveltekit-node	151	0	9
✅ sveltekit-quickjs	151	0	9
✅ tanstack-start-node	132	0	28
✅ tanstack-start-quickjs	132	0	28
✅ vite-node	132	0	28
✅ vite-quickjs	132	0	28

❌ 💻 Local Development

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
❌ tanstack-start-quickjs	133	1	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 📦 Local Production

App	Passed	Skipped
✅ astro-stable-node	134	26
✅ astro-stable-quickjs	134	26
✅ express-stable-node	134	26
✅ express-stable-quickjs	134	26
✅ fastify-stable-node	134	26
✅ fastify-stable-quickjs	134	26
✅ hono-stable-node	134	26
✅ hono-stable-quickjs	134	26
✅ nest-stable-node	134	26
✅ nest-stable-quickjs	134	26
✅ nextjs-turbopack-canary-node	141	19
✅ nextjs-turbopack-canary-quickjs	141	19
✅ nextjs-turbopack-stable-node	160	0
✅ nextjs-turbopack-stable-quickjs	160	0
✅ nextjs-webpack-canary-node	141	19
✅ nextjs-webpack-canary-quickjs	141	19
✅ nextjs-webpack-stable-node	160	0
✅ nextjs-webpack-stable-quickjs	160	0
✅ nitro-stable-node	134	26
✅ nitro-stable-quickjs	134	26
✅ nuxt-stable-node	134	26
✅ nuxt-stable-quickjs	134	26
✅ sveltekit-stable-node	153	7
✅ sveltekit-stable-quickjs	153	7
✅ tanstack-start-node	134	26
✅ tanstack-start-quickjs	134	26
✅ vite-stable-node	134	26
✅ vite-stable-quickjs	134	26

✅ 🐘 Local Postgres

App	Passed	Skipped
✅ astro-stable-node	134	26
✅ astro-stable-quickjs	134	26
✅ express-stable-node	134	26
✅ express-stable-quickjs	134	26
✅ fastify-stable-node	134	26
✅ fastify-stable-quickjs	134	26
✅ hono-stable-node	134	26
✅ hono-stable-quickjs	134	26
✅ nest-stable-node	134	26
✅ nest-stable-quickjs	134	26
✅ nextjs-turbopack-canary-node	141	19
✅ nextjs-turbopack-canary-quickjs	141	19
✅ nextjs-turbopack-stable-node	160	0
✅ nextjs-turbopack-stable-quickjs	160	0
✅ nextjs-webpack-canary-node	141	19
✅ nextjs-webpack-canary-quickjs	141	19
✅ nextjs-webpack-stable-node	160	0
✅ nextjs-webpack-stable-quickjs	160	0
✅ nitro-stable-node	134	26
✅ nitro-stable-quickjs	134	26
✅ nuxt-stable-node	134	26
✅ nuxt-stable-quickjs	134	26
✅ sveltekit-stable-node	153	7
✅ sveltekit-stable-quickjs	153	7
✅ tanstack-start-node	134	26
✅ tanstack-start-quickjs	134	26
✅ vite-stable-node	134	26
✅ vite-stable-quickjs	134	26

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack-node	160	0	0
✅ nextjs-turbopack-quickjs	160	0	0

❌ 🌐 Cross-language Conformance

App	Passed	Failed	Skipped
❌ python	0	9	132

✅ vercel-http-transport

App	Passed	Skipped
✅ example	132	28
✅ express	132	28
✅ hono	132	28
✅ nextjs-turbopack	157	3
✅ nitro	132	28
✅ vite	132	28

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

✅ vercel-ws-transport

App	Passed	Skipped
✅ example	132	28
✅ express	132	28
✅ nextjs-turbopack	157	3
✅ vite	132	28

📋 View full workflow run

github-actions · 2026-08-22T01:18:39Z

📊 Workflow Benchmarks

commit 6154e23 · Sat, 22 Aug 2026 01:44:03 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	231 (-69%) 💚	1312 🔴 (+31%) 🔻	1345 🔴 (+29%) 🔻	1431 🔴 (+19%) 🔻	30
TTFS	stream	255 (+23%) 🔻	1347 🔴 (+37%) 🔻	1362 🔴 (+36%) 🔻	1408 🔴 (+38%) 🔻	30
TTFS	hook + stream	1523 (+35%) 🔻	1644 🔴 (+24%) 🔻	1679 🔴 (+17%) 🔻	1951 🔴 (+29%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	594 (+12%)	1069 (+19%) 🔻	1247 (-18%) 💚	2155 (+17%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	1880 (+12%)	4211 (+24%) 🔻	5371 (+47%) 🔻	6161 (-8.3%)	10
STSO	1020 steps (inline)	120 (+22%) 🔻	149 (+14%)	173 (+15%) 🔻	264 (+10%)	1019
WO	1020 steps	151631 (+14%)	151631 (+14%)	151631 (+14%)	151631 (+14%)	1
CRTT	first chunk (pooled)	101 (+22%) 🔻	169 (+24%) 🔻	223 (+11%)	335 (-3.2%)	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	131 (+8%)	161 (+17%)	415 (+114%)	766 (+143%)	157 (+41%)	10
size sweep (100/s, 160B-12KB)	141 (+33%)	148 (-8%)	237 (-6%)	587 (-53%)	122 (-13%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	161 (+44%)	149 (+7%)	203 (+8%)	501 (-27%)	378 (+24%)	3
replay eve-gpt-5.6-sol-2000t (1x)	183 (+80%)	138 (-8%)	193 (-25%)	386 (-47%)	369 (-19%)	2
replay eve-gpt-5.6-sol-2000t (2x)	134 (+21%)	542 (+85%)	2653 (+79%)	4659 (+50%)	547 (+50%)	3

📈 STSO distribution vs main (inline / queue-hop histograms)

1020 steps (inline)

Cumulative STSO time: main 133406ms → this run 150292ms (Δ +16886ms, +13%)

  50-100 ms  ┃                         main   1  this   0    -1
 100-150 ms  ███████████████████┃████  main 910  this 771  -139
 150-200 ms  ██░░░┃                    main  89  this 219  +130
 200-250 ms  ┃                         main  10  this  17    +7
 250-300 ms  ┃                         main   6  this   6    +0
 300-350 ms  ┃                         main   2  this   0    -2
 350-400 ms  ┃                         main   0  this   5    +5
 450-500 ms  ┃                         main   1  this   0    -1
950-1000 ms  ┃                         main   0  this   1    +1

📈 CRTT drill-down vs main (RTT distributions & profiles)

variant  RTT 1ms→5s+             avg         p50          p90          p99     n
control  ······▄█▂▁···  148.2 (+28%)   116 (+8%)  415 (+114%)  766 (+143%)  3000
sweep    ······▄█▁▁···  128.8 (-16%)   116 (+6%)    237 (-6%)   587 (-53%)  3000
gw 1x    ·····▁▅█▂▁···  129.8 (+17%)  112 (+18%)    203 (+8%)   501 (-27%)  5295
eve 1x   ·····▁▇█▂▁···   121.5 (-9%)   104 (-3%)   193 (-25%)   386 (-47%)  5186
eve 2x   ·····▁▃█▃▁▁▁·  352.8 (+35%)  140 (-10%)  2653 (+79%)  4659 (+50%)  7779

RTT over stream progress (avg per tenth of stream, bars scaled min→max):

control  ▆█▄▅█▆▃▁▂▁  111–187ms
sweep    ▅▄▃▁▁▂▁▃▄█  113–164ms
gw 1x    ▃▁▁▃▄▂█▂▄▅  115–161ms
eve 1x   ▄▄▃▃▁▁▅█▄▃  104–151ms
eve 2x   ▄█▄▁▁▁▂▂▂▂  120–1164ms

RTT by chunk size (avg per log size bin, ~160B → ~12KB serialized, bars scaled min→max):

sweep  ▅▅█▄▁▃▁  127–132ms

Delivery jitter over stream progress (avg positive CDV per tenth of stream, bars scaled min→max):

control  ▁█▅█▃▃▃▅▂▂  37–47ms
sweep    ▁█▄▃▄▅▄▃▆▄  38–64ms
gw 1x    ▃▁▃▃▅▄█▃▃▅  30–48ms
eve 1x   ▅█▁▂▁▁▇▆█▅  21–27ms
eve 2x   █▂▁▂▂▂▂▂▂▂  17–75ms

ℹ️ Metric definitions & methodology

_{Streams: first-chunk RTT (the stream-open path, before any buffering/backpressure), CRTT percentiles, and worst delivery stall (CDV max). Cells are medians across iterations; per-run values in the artifacts. No 🔴/🟢 marks until targets attach.}

_{The collapsed STSO distribution section above buckets every step gap, split inline (same warm process — pure framework overhead) vs queue-hop (fresh process — dispatch, reinit, replay). █ = main, ┃ = this run, ░ = fill.}

_{The collapsed CRTT drill-down: per-variant RTT histograms (fixed log bins, · = empty) and mean RTT/positive-CDV profile lines over stream progress and chunk size. Histograms, avgs, and profiles merge exactly across runs; p50–p99 are percentile-of-percentiles. Per-index rows live in the artifacts.}

_{Best/P75/P90/P99 deltas compare against the most recent benchmark run on main at the time of this run. 🔻 flags a delta worse than +15%, 💚 one better than −15%.}

_{Metrics — TTFS: time to first step body (in-deployment start() → first step body) · Fan-out TTFS: fan-out time to first step (in-deployment start() → first of the parallel step bodies to complete) · Fan-out TTLS: fan-out time to last step (in-deployment start() → last of the parallel step bodies to complete, i.e. when the Promise.all resolves) · STSO: step-to-step overhead (gap between consecutive step bodies) · WO: workflow overhead (whole-run time outside step bodies, in-deployment anchored) · CRTT: chunk round-trip time (per-chunk write → read latency, one clock domain: deployment → stream backend → same deployment) · CDV: chunk delay variation / delivery jitter (inter-arrival gap minus inter-write gap per seq-adjacent pair; skew-free; the row is each run's MAX positive value, so one stall moves it)}

_{Scenarios — step: one trivial no-op step, no stream; no hooks, so the run stays in turbo mode (in-process fast path) · stream: one streaming step; no hooks, so the run stays in turbo mode (in-process fast path) · hook + stream: registers a hook before one step, which exits turbo mode (dispatch path) · 1020 steps: 1020 trivial sequential steps; STSO is measured between consecutive steps in the given step ranges, and WO is the whole-run overhead outside step bodies · Promise.all(100 steps): 100 trivial no-op steps started together in a single Promise.all; Fan-out TTFS is the first of them to complete and Fan-out TTLS the last, both from the in-deployment clientStart, so their gap is the spread the runtime adds across the fan-out · paced control (100/s, 60B): the control: 300 tiny (~60B) deltas metronome-paced at 100/s — zero workload structure, so it reads the transport floor and flush cadence, and disambiguates transport-wide vs workload-specific when a replay row moves · size sweep (100/s, 160B-12KB): same pacing as the control with deltas padded in rotation across seven log-spaced sizes (~160B–12KB) — rotation decouples size from stream position, so it isolates whether chunk size causes latency · replay gateway-gpt-5.4-nano-2000t (1x): raw provider SSE cadence captured at the AI gateway boundary (gpt-5.4-nano, the most popular gateway model; per-token deltas p50 208B = the modal production chunk size), replayed exactly as measured — the typical customer's workload; its CDV is the typical customer's real delivery jitter · replay eve-gpt-5.6-sol-2000t (1x): a captured eve turn (gpt-5.6-sol, the most-used demanding eve model; ~2000 output tokens = production p50 turn length) replayed exactly as measured — eve's envelope protocol re-ships the cumulative message so sizes ramp 142B→13KB; the demanding outlier tenant's reality · replay eve-gpt-5.6-sol-2000t (2x): the same eve capture at 2x — the headroom/stress row; real fast-tier models emit the same chunk sizes at proportionally higher rate, so time compression is a faithful speed model · first chunk (pooled): every run's seq-0 RTT pooled across all stream scenarios — the first chunk precedes any workload differentiation, so pooling samples one shared stream-open path with exact percentiles}

_{Replay cadences (semantic sha256) — eve-gpt-5.6-sol-2000t eaf22f5946e7c61f3c65c7006d550df180cfabd4e706254a09f22aec0cfb420d · gateway-gpt-5.4-nano-2000t 6f24ac518b6b83ff1d0e85a5fe78230db192716d66a7fc6b2fe022752001d041}

_{🔴 marks a percentile over its target (within target is left unmarked). Targets (p75/p90/p99, ms) — TTFS 200/300/600}

_{All timestamps are deployment-side; runs are triggered in-deployment, so the CI runner and api.vercel.com sit outside every measured window. TTFS = start() → first step body (includes dispatch + any cold start); Fan-out TTFS/TTLS = first/last step completion of one Promise.all from the same anchor (the gap is the runtime’s fan-out spread); STSO/WO between step bodies; CRTT inside the workflow (excludes the api.vercel.com read path).}

_{Cold starts stay in the numbers (real bursty-workload latency, inflates P75+); Best is the warm floor.}

github-actions · 2026-08-22T01:21:55Z

Sim World

Simulated world deterministic testing for races. Traces

🟠 world-sim scenario book — 1 fail of 41 total

fence=per-spec

scenario	outcome	events	virt	replay
✅ `smoke-no-steps`	completed	3	0ms	ok
✅ `smoke-one-step`	completed	6	0ms	ok
✅ `hook-at-step-started`	completed	12	0ms	ok
✅ `hook-at-step-completed`	completed	12	0ms	ok
✅ `hook-at-hook-created`	completed	12	0ms	ok
✅ `deadline-hook-wins`	completed	7	1.0h	ok
✅ `deadline-expires`	completed	7	1.0h	ok
✅ `long-sleep`	completed	11	30.0d	ok
✅ `hook-never-arrives`	stalled	3	0ms	skipped
✅ `step-retries-twice`	completed	10	2.0s	ok
✅ `parallel-steps`	completed	9	0ms	ok
✅ `hook-on-execution-state`	completed	12	0ms	ok
✅ `peek-hook-before-branch`	completed	12	0ms	ok
✅ `peek-hook-after-branch`	completed	12	0ms	ok
✅ `peek-hook-at-registration`	completed	12	0ms	ok
✅ `race-hook-before-probe`	completed	12	0ms	ok
✅ `race-hook-after-probe`	completed	12	0ms	ok
✅ `race-duplicate-delivery`	completed	13	0ms	ok
✅ `attr-hook-before-step`	completed	11	0ms	ok
✅ `attr-hook-after-step`	completed	11	0ms	ok
✅ `attr-from-step-body`	completed	13	0ms	ok
✅ `fork-hook-after-timeout`	completed	14	1.0m	ok
✅ `fork-hook-before-timeout`	completed	14	1.0m	ok
✅ `count-hook-after-timeout`	completed	17	1.0m	ok
✅ `count-hook-before-timeout`	completed	20	1.0m	ok
✅ `stale-read-step-count-fork`	completed	20	1.0m	ok
✅ `stale-read-equal-step-counts`	completed	14	1.0m	ok
✅ `step-vs-step-fork`	completed	12	0ms	ok
✅ `step-vs-step-fork-fenced`	completed	12	0ms	ok
✅ `fence-catches-benign-direction`	completed	12	5ms	ok
✅ `in-flight-before-decision`	completed	17	1.0m	ok
❌ `in-flight-before-decision-counted`	completed	17	1.0m	ok
✅ `in-flight-after-decision`	completed	19	2.0m	ok
✅ `stale-read-step-count-fork-fenced`	completed	20	1.0m	ok
✅ `fork-hook-wins`	completed	13	1.0m	ok
✅ `fork-timeout-wins`	completed	13	1.0m	ok
✅ `unclaimed-payload-under-fork`	completed	17	1.0m	ok
✅ `claimed-payload-under-fork`	completed	17	1.0m	ok
✅ `writers-independent-step-bodies`	completed	12	0ms	ok
✅ `writers-scripted-tempo`	completed	12	0ms	ok
✅ `cancel-mid-step`	cancelled	7	0ms	skipped

Full trace: world-sim.txt

vercel

Additional Suggestion:

The sleepWinsRaceWorkflow sleep was raised to 6s but the test still asserts durationMs < 8_000ms, leaving too little headroom for Vercel resume/queue/cold-start overhead, making the assertion flaky.

[e2e] Probe: raise 1s workflow sleeps to 6s

6154e23

Co-Authored-By: shalabhc <shalabh.chaturvedi@vercel.com>

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shalabhc mentioned this pull request Aug 22, 2026

[probe] Disable wait-continuation dedupe #3748

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[e2e] Probe: raise 1s workflow sleeps to 6s - #3744

[e2e] Probe: raise 1s workflow sleeps to 6s#3744
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shalabhc commented Aug 22, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Not for merge — diagnostic probe

What this actually tests (revised)

Reading the result

Confound to control next

Also raises five outputStream test timeouts 60s → 120s

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🧪 E2E Test Results

❌ Failed E2E Tests

▲ Vercel Production (8 failed)

💻 Local Development (1 failed)

🌐 Cross-language Conformance (9 failed)

⚠️ Flaky E2E Tests (passed on retry)

🛠 Infra Events (absorbed by the harness)

E2E Test Summary

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📊 Workflow Benchmarks

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Sim World

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shalabhc commented Aug 22, 2026 •

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