node:worker_threads: +48 Node.js tests passing — MessagePort, stdio, SHARE_ENV, exit codes, transfer semantics, postMessageToThread + inspector

[cirospaciari]

Compatibility — node worker_threads test suites (debug build vs bun 1.3.13, which passes 51/138 parallel + 2/5 sequential):

	parallel	sequential	combined
worker_threads	102/138	2/5	104/143 (72.7%)

Improves Node.js worker_threads compatibility across MessagePort, captured stdio, environment sharing, structured-clone transfer semantics, Worker construction and error handling, and ports the upstream Node worker tests these fix (plus a batch that already passed).

MessagePort

• Move the EventEmitter helpers (on/off/once/emit/addListener/removeListener/…) off MessagePort.prototype onto an intermediate prototype so Object.getOwnPropertyNames(MessagePort.prototype) matches Node.
• close([callback]): the callback runs asynchronously after the synchronous detach.
• Dispatch the 'close' event natively, once (guarded), after delivering queued messages, to both the closed port and its entangled peer (including nested in-transit transferred ports); release the peer's event-loop ref.
• Deliver messages already queued in a port's inbox when close() is called mid-dispatch.
• moveMessagePortToContext throws ERR_CLOSED_MESSAGE_PORT for a closed port.
• postMessage transfer-list errors match Node: source/peer port → DataCloneError "Transfer list contains source port"; already-detached port → "...already detached" (validated before any ArrayBuffer detach); a MessagePort in the message but not in the transfer list → DataCloneError "Object that needs transfer was found in message but not listed in transferList".
• Node-compatible util.inspect output.
• postMessage to a port's own entangled peer warns (not throws) and loses the channel, matching Node; every transfer-list port is still detached (transfer is atomic), and the source-port check is order-independent within the transfer list.

markAsUntransferable / markAsUncloneable / isMarkedAsUntransferable

• Mark objects with non-enumerable registry-symbol markers, enforced in the structured-clone serializer: a marked-untransferable object in a transfer list throws DataCloneError before any detach; a marked-uncloneable object throws when cloned/posted (ArrayBuffers/views excepted, matching Node).

postMessageToThread

• worker_threads.postMessageToThread(threadId, value[, transferList][, timeout]) and the process 'workerMessage' event (Node 22+). The main thread is a hub holding a control MessagePort to every thread; each worker keeps one port to the hub, so any thread can reach any other. Errors map to ERR_WORKER_MESSAGING_* (same-thread / failed / errored / timeout).
• Fixed MessagePort.unref() to release the event-loop ref taken by a message listener (previously only the onmessage/ref() keepalive was released), so an always-listening control port no longer pins a worker's loop.

env: SHARE_ENV

• A Worker created with env: SHARE_ENV shares a live, process-wide environment with the parent (write-through process.env over a lock-guarded store; reads/writes/deletes/enumeration). The normal snapshot path is unchanged; env: 42 still throws ERR_INVALID_ARG_TYPE.

Captured stdio

• new Worker(f, { stdin/stdout/stderr: true }): worker.stdout/stderr are Readables fed by the worker's process.stdout/stderr (including console.log); worker.stdin is a Writable. Streams are ended when the worker exits; the stdin listener attaches lazily so an unread {stdin:true} worker doesn't stay alive.

Worker construction & lifecycle

• Worker#threadName + threadName export; validate the filename like Node (ERR_WORKER_PATH / ERR_INVALID_URL_SCHEME); terminate() keeps the loop alive until it resolves; normalize options for new Worker(f, null); eval: false validates the path.

Worker introspection (Node 24)

• worker.getHeapStatistics(), worker.cpuUsage([prevValue]), worker.startCpuProfile([options]) (returns a handle with an idempotent stop()), and worker.startHeapProfile([options]) — sampled from the worker thread across threads (mirroring getHeapSnapshot), with Node-matching synchronous option validation and ERR_WORKER_NOT_RUNNING once the worker has exited.

Top-level await

• A worker whose entry module has an unsettled top-level await now exits with code 13 instead of hanging; a top-level await still waiting on real work is unaffected.

Errors

• A worker entry/import parse failure surfaces a real SyntaxError to the parent's error event.

Worker process surface

• On a worker thread process.abort/chdir (and setuid/seteuid/setgid/setegid/setgroups/initgroups off Windows) are disabled stubs that throw ERR_WORKER_UNSUPPORTED_OPERATION (with .disabled === true), process.umask(setMask) throws (the getter still works), debugPort defaults to 9229, and the main-only _startProfilerIdleNotifier/_stopProfilerIdleNotifier/_debugProcess/_debugEnd internals are removed — fixing process.abort() taking down the whole process from a worker. The IPC surface (send/disconnect/channel/connected) is disabled only when an IPC channel was inherited (NODE_CHANNEL_FD set), so if (process.send) still works in a normal worker.

Crash & teardown safety

• Serializing an error whose stack getter throws (a throwing Error.prepareStackTrace) no longer crashes postMessage.
• A worker that throws during a beforeExit handler exits cleanly with code 1 instead of SIGTRAP.
• Terminating a worker mid-HTTP/2 no longer crashes the process: the HTTP/2 frame parser stops dispatching to JS once the worker is tearing down (no empty-value or pending-exception JS calls).

Worker entry resolution

• A Worker pointed at a missing entry file reports Cannot find module '<path>' (code MODULE_NOT_FOUND), matching Node, instead of the native loader's ModuleNotFound message.

Tests

Ports the upstream Node worker tests for all of the above, plus a set that already passed. Existing Bun worker tests were updated where behavior is now Node-aligned (workers constructed from URL objects, not file:// strings; close delivers queued messages; parse errors are SyntaxError; eval:false validates the path).

---

no test proof · iteration 131 · Platform-specific test(s) that do not run on this machine. Deferring to CI, which covers all platforms: test/js/node/worker_threads/worker_heap_snapshot_gc.test.ts

[robobun]

^{Updated 4:16 PM PT - Jul 10th, 2026}

⏳ @cirospaciari, your commit 13a7f81 is still building in Build #71656, but has 1 failures so far (All Failures):

• test/js/bun/http/proxy-stress-concurrent.test.ts - code 1 on 🍎 14 x64

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Walkthrough

Adds C++ MessagePort peer-close and transfer validation; exposes threadName and port-activity to JS; refactors JS MessagePort emitter/close behavior; validates worker filenames/names; implements captured stdio via MessageChannel; updates moveMessagePortToContext and Worker lifecycle/getters; and adds comprehensive tests.

Changes

Worker Threads Node.js Compatibility

Layer / File(s)	Summary
MessagePort C++ interface src/jsc/bindings/webcore/MessagePort.h, src/jsc/bindings/webcore/MessagePort.cpp	Adds MessagePort::peerClosed() and rejects detached JSMessagePort in transfer lists; refines DataCloneError messages.
MessagePortPipe peer notification src/jsc/bindings/webcore/MessagePortPipe.cpp, src/jsc/bindings/webcore/MessagePortPipe.h	Notify entangled peer on close by posting a task to the peer's script context and invoking peerClosed().
Worker native binding: threadName & port activity src/jsc/bindings/webcore/Worker.cpp	Expose threadName and isMessagePortActive from native createNodeWorkerThreadsBinding and include MessagePortPipe for activity checks.
JS: name normalization & filename validation src/js/node/worker_threads.ts	Add normalizeWorkerName and validateWorkerFilename; read _threadName/_isMessagePortActive from native binding.
JS: MessagePort emitter and captured stdio src/js/node/worker_threads.ts	Refactor injectFakeEmitter to insert an intermediate prototype, override MessagePort.prototype.close to synchronously emit "close" and track closed ports, and implement captured-stdio plumbing with MessageChannel control ports; derive module threadName.
JS: moveMessagePortToContext and Worker state src/js/node/worker_threads.ts	Change moveMessagePortToContext(port, context) to validate port instances/closed status; add Worker private fields (#name, #exited) and initialize #name from normalized options.
JS: Worker stdio getters and transfer wiring src/js/node/worker_threads.ts	Worker constructor creates MessageChannel pairs for requested stdio, transfers worker-side ports via workerData/transferList, and implements lazy stdin/stdout/stderr getters backed by control ports.
JS: terminate and threadName lifecycle src/js/node/worker_threads.ts	terminate() calls ref() before terminating; #onClose sets #exited = true; add Worker.threadName getter and export module threadName.
MessagePort peer/transfer tests test/js/node/test/parallel/test-worker-message-*.js, test/js/node/test/parallel/test-worker-message-port-transfer-self.js	Add tests for ArrayBuffer neutering, port transferring, self-transfer DataCloneError, closed/detached transfer errors, SharedArrayBuffer lists, and message ordering around close.
Worker stdio & drain tests test/js/node/test/parallel/test-worker-stdio*.js, test/js/node/test/parallel/test-worker-message-port-drain.js	Tests for stdout/stdin capture, flush ordering, piping, and per-worker stdout drain behaviour.
Worker lifecycle & termination tests test/js/node/test/parallel/test-worker-thread-name.js, test/js/node/test/parallel/test-worker-terminate-*.js, test/js/node/test/parallel/test-worker-nexttick-terminate.js	Validate threadName behavior, termination during microtasks/nextTick/unref, and termination while async operations are in flight.
Worker init, path, and error tests test/js/node/test/parallel/test-worker-unsupported-path.js, test/js/node/test/parallel/test-worker-heapdump-failure.js, test/js/node/test/parallel/test-worker-init-failure.js, test/js/node/test/parallel/test-worker-memory.js	Tests for invalid specifiers, heap snapshot behavior on non-running workers, init failures under FD limits, and memory-regression checks.
Worker exit/transfer semantics tests test/js/node/test/parallel/test-worker-crypto-sign-transfer-result.js, test/js/node/test/parallel/test-worker-process-exit-async-module.js, test/js/node/test/parallel/test-worker-voluntarily-exit-*.js, test/js/node/test/parallel/test-worker-terminate-source-map.js	Verify crypto buffer transfers, process.exit ordering in async modules, voluntary exit semantics, and source-map shutdown isolation.
Sequential FD coordination tests test/js/node/test/sequential/test-worker-fshandles-*.js	Sequential tests exercising fd open/close during recursive worker spawning and termination.
Unit test adjustments test/js/node/worker_threads/worker_threads.test.ts	Adjust moveMessagePortToContext test to pass a real MessagePort and relax expected MessagePort string form in serialization test.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title is clearly about the worker_threads compatibility and test batch, so it matches the main change despite being verbose.
Description check	✅ Passed	The description is detailed and covers the PR goals plus some verification context, so it is mostly complete.

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[github-actions]

Found 5 issues this PR may fix:

1. Bun doesn't finish the execution when all workers' ports are closed #11760 - PR adds peer close events so closing one side of a MessageChannel now releases the entangled peer's event-loop ref, fixing the hang
2. MessagePort missing removeListener method (Node.js EventEmitter incompatibility) #29022 - PR moves EventEmitter-style helpers onto MessagePort's intermediate prototype, adding the missing removeListener method
3. worker_threads stdout/stderr not implemented for Worker #28039 - PR implements { stdin: true, stdout: true, stderr: true } options for Worker using MessageChannel pairs
4. worker_threads.Worker option "stdout" is not yet implemented in Bun #23875 - PR implements the stdout option for worker_threads.Worker
5. Worker STDIN and STDOUT throw NotImplemented Exceptions #14563 - PR implements Worker stdin/stdout/stderr support, resolving the NotImplemented exceptions

If this is helpful, copy the block below into the PR description to auto-close these issues on merge.

Fixes #11760
Fixes #29022
Fixes #28039
Fixes #23875
Fixes #14563

🤖 Generated with Claude Code

[github-actions]

This PR may be a duplicate of:

1. worker_threads: implement parentPort.close()/ref()/unref()/hasRef() #30549 - Implements parentPort.close()/ref()/unref()/hasRef(), which overlaps with this PR's MessagePort close(callback) and ref/unref lifecycle changes
2. worker_threads: implement Worker#stdout/stderr/stdin (1hw6ic) #29826 - Implements Worker#stdout/stderr/stdin, which overlaps with this PR's worker stdio capture via MessageChannel control ports
3. feat(worker_threads): implement stdout/stderr for Worker #26599 - Implements Worker stdout/stderr, which overlaps with this PR's worker stdio implementation
4. worker_threads: give MessagePort node's EventEmitter surface #29024 - Adds Node EventEmitter aliases to MessagePort, which overlaps with this PR's MessagePort EventEmitter restructuring
5. fix(MessagePort): emit "close" event on both ports when one side is closed #27691 - Emits close event on both ports when one side is closed, which overlaps with this PR's MessagePort peer close event

🤖 Generated with Claude Code

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Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/js/node/worker_threads.ts`:
- Around line 389-398: The parameter "context" in function
moveMessagePortToContext is declared but unused; to satisfy the linter and
indicate intentional non-use, rename it to "_context" (i.e., change the
parameter from context to _context) in the moveMessagePortToContext signature
and keep the rest of the function unchanged (retaining the MessagePort checks
and the throwNotImplemented("worker_threads.moveMessagePortToContext") call).

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📒 Files selected for processing (35)

• src/js/node/worker_threads.ts
• src/jsc/bindings/webcore/MessagePort.cpp
• src/jsc/bindings/webcore/MessagePort.h
• src/jsc/bindings/webcore/MessagePortPipe.cpp
• src/jsc/bindings/webcore/MessagePortPipe.h
• src/jsc/bindings/webcore/Worker.cpp
• test/js/node/test/parallel/test-worker-crypto-sign-transfer-result.js
• test/js/node/test/parallel/test-worker-dns-terminate.js
• test/js/node/test/parallel/test-worker-heapdump-failure.js
• test/js/node/test/parallel/test-worker-init-failure.js
• test/js/node/test/parallel/test-worker-memory.js
• test/js/node/test/parallel/test-worker-message-channel.js
• test/js/node/test/parallel/test-worker-message-port-arraybuffer.js
• test/js/node/test/parallel/test-worker-message-port-close.js
• test/js/node/test/parallel/test-worker-message-port-drain.js
• test/js/node/test/parallel/test-worker-message-port-message-before-close.js
• test/js/node/test/parallel/test-worker-message-port-message-port-transferring.js
• test/js/node/test/parallel/test-worker-message-port-multiple-sharedarraybuffers.js
• test/js/node/test/parallel/test-worker-nexttick-terminate.js
• test/js/node/test/parallel/test-worker-process-exit-async-module.js
• test/js/node/test/parallel/test-worker-stdio-flush-inflight.js
• test/js/node/test/parallel/test-worker-stdio-flush.js
• test/js/node/test/parallel/test-worker-stdio.js
• test/js/node/test/parallel/test-worker-terminate-microtask-loop.js
• test/js/node/test/parallel/test-worker-terminate-ref-public-port.js
• test/js/node/test/parallel/test-worker-terminate-source-map.js
• test/js/node/test/parallel/test-worker-terminate-unrefed.js
• test/js/node/test/parallel/test-worker-thread-name.js
• test/js/node/test/parallel/test-worker-uncaught-exception.js
• test/js/node/test/parallel/test-worker-unsupported-path.js
• test/js/node/test/parallel/test-worker-voluntarily-exit-followed-by-addition.js
• test/js/node/test/parallel/test-worker-voluntarily-exit-followed-by-throw.js
• test/js/node/test/sequential/test-worker-fshandles-error-on-termination.js
• test/js/node/test/sequential/test-worker-fshandles-open-close-on-termination.js
• test/js/node/worker_threads/worker_threads.test.ts

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Inline comments:
In `@src/js/node/worker_threads.ts`:
- Around line 216-226: The custom inspect function attached to MessagePort via
the kInspectCustom symbol declares unused parameters depth and options which
trigger the linter; update the function signature on MessagePort.prototype (the
value function assigned to kInspectCustom) to prefix those parameters with
underscores (e.g., _depth, _options) so the signature still matches
util.inspect.custom while satisfying the linter.

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⚠️ Outside diff range comments (1)

src/js/node/worker_threads.ts (1)

405-409: ⚠️ Potential issue | 🟠 Major | 🏗️ Heavy lift

moveMessagePortToContext() only recognizes JS-initiated closes.

closedMessagePorts is updated only by the JS MessagePort.prototype.close() wrapper, but this PR also closes ports from native code (MessagePort::peerClosed() in src/jsc/bindings/webcore/MessagePort.cpp, plus teardown paths). Those ports will now be observably closed without ever entering this WeakSet, so this branch still falls through to throwNotImplemented() instead of ERR_CLOSED_MESSAGE_PORT.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@src/js/node/worker_threads.ts` around lines 405 - 409,
moveMessagePortToContext currently only checks the JS-side WeakSet
closedMessagePorts and misses ports closed from native (e.g.,
MessagePort::peerClosed()), causing the code path to fall through instead of
throwing ERR_CLOSED_MESSAGE_PORT; update moveMessagePortToContext (and related
MessagePort close handling) to detect native-initiated closes by reading a
JS-visible closed flag that native code sets (e.g., a new internal slot or
property on the MessagePort object that native MessagePort::peerClosed()
updates), or alternatively ensure native close paths also add the port to the
existing closedMessagePorts WeakSet; reference moveMessagePortToContext and
closedMessagePorts and make sure the native MessagePort::peerClosed() path
updates the same JS-visible state so moveMessagePortToContext throws
$ERR_CLOSED_MESSAGE_PORT for native-closed ports.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/js/node/worker_threads.ts`:
- Around line 208-209: The callback passed to close(cb) is queued with
queueMicrotask(cb) which loses the MessagePort receiver; update the close
implementation (MessagePort.prototype.close / close(cb)) to invoke the queued
microtask as a wrapper that calls the original cb with the MessagePort as
receiver (e.g., queueMicrotask(() => cb.call(this))) after the existing typeof
cb check so the callback runs with this === MessagePort while still being
scheduled asynchronously.

---

Outside diff comments:
In `@src/js/node/worker_threads.ts`:
- Around line 405-409: moveMessagePortToContext currently only checks the
JS-side WeakSet closedMessagePorts and misses ports closed from native (e.g.,
MessagePort::peerClosed()), causing the code path to fall through instead of
throwing ERR_CLOSED_MESSAGE_PORT; update moveMessagePortToContext (and related
MessagePort close handling) to detect native-initiated closes by reading a
JS-visible closed flag that native code sets (e.g., a new internal slot or
property on the MessagePort object that native MessagePort::peerClosed()
updates), or alternatively ensure native close paths also add the port to the
existing closedMessagePorts WeakSet; reference moveMessagePortToContext and
closedMessagePorts and make sure the native MessagePort::peerClosed() path
updates the same JS-visible state so moveMessagePortToContext throws
$ERR_CLOSED_MESSAGE_PORT for native-closed ports.

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