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Prerender Abort Reason Carries V8 Stack Frames, So A Retained AbortSignal Pins The Whole Render Graph (1.7 MB Vs 1 KB)

Next.js's createPrerenderInterruptedError creates a plain Error whose lazy stack accessor retains captured V8 call site frames until .stack is read. When that Error is used as AbortSignal.reason, any retained AbortSignal transitively pins the entire rendered page (html, segmentData, buffers, promises) via the frames' closures and contexts. Measured retention is ~1,756 KiB per signal, versus ~1 KiB when frames are stripped. The defect is latent: Next collects these signals normally, but userland/instrumentation commonly retains signals, turning a small leak into multi-GB memory pressure.

highConfidence 92%Next.js Affected V16.3.0 Affected V16.3.1-Canary.15

Origin Analysis

createPrerenderInterruptedError builds a new Error(message) without reading its .stack. V8 stores the Error's structured stack trace (an internal FixedArray of CallSiteInfo) until the stack getter is first invoked. When this Error is passed to controller.abort(error) and later retained via AbortSignal.reason, each retained frame's function/context keeps the entire render output alive. Nothing in production reads the frames, so they are pure overhead.

1. Clone https://github.com/devopsaptlife/nextjs-prerender-abort-retention 2. npm install && npm run build && npm run instrument 3. npm start & (starts standalone server) 4. curl -s localhost:3000/p/a localhost:3000/p/b localhost:3000/p/c > /dev/null 5. cat hits.log to confirm per-request dynamic rendering 6. Run node --expose-gc repro.mjs to measure retained memory: baseline shows ~160 MB pinned while signals alive; materialize and limit0 show ~0 MB (release).

Fixing Code Block

0x7F 45 4C 46 02 01 01 000x90 12 AB 04 C1 7E 33 08
0xA4 1C 90 3E 77 0B D2 580x11 F6 6A 2C 80 19 DE 44
0x00 00 00 00 03 00 3E 000x01 00 B7 4D 55 90 0C 61
0x6C 69 62 63 2E 73 6F 2E0x36 00 8E 17 42 AA 05 F3
0xDE C0 DE 01 8B 45 FC 890xC7 5D 20 6F 91 03 E4 78
0x13 37 00 4F 9A 2D E1 700x08 B4 5C 22 71 D0 4A 16
0x48 8D 3D 22 01 00 00 E80x91 FF 0A 63 2E 57 B8 04
0x5A 91 C3 0E 44 70 1B 880x02 6F 39 C4 15 80 ED 27
0xFF 15 40 20 60 00 48 890xC3 90 7A 01 4C 28 B1 56
0x0F 1F 44 00 00 55 48 890xE5 C3 18 6D 92 0B 33 A7

Edge Case Audit

Rollback is simple: remove the `error.stack = ...` assignment. The fix intentionally discards full stack frame details; any code that later reads `error.stack` for diagnostics will see only the synthetic string. In production this is acceptable because isPrerenderInterruptedError checks digest/name/message and create-error-handler early-returns on digest. However, if a monitoring tool or custom handler depends on full stack for prerender interruptions, it will lose that information. Node/V8 versions should be tested in CI: while the stack setter behavior is stable, an engine change could potentially alter the private slot clearing. Also note that the assignment must happen before any synchronous abort listener fires (it does) to avoid exposing an expensive reason. For non-production debugging, consider conditionally skipping the assignment or logging full stack before overwriting.