node:http: queue the server 'close' check from the connection's close handler, not from a socket 'close' listener by robobun · Pull Request #45257 · oven-sh/bun

robobun · 2026-10-14T17:43:14Z

Problem

Since 1.4.3 (node:http: the server follows Node (request body, framing, response finish, lifecycle) #43557) the server's 'close' check for the last connection is a listener on that socket: this.once("close", ...) in NodeHTTPServerSocket.#onClose (src/js/node/_http_server.ts:1852 on main), behind the program's listeners.
When the socket's 'close' emit does not reach it, server.close(cb), the server's 'close' and asyncDispose never come. A program listener that throws ends the emit. socket.removeAllListeners() loses it with no exception. Node and 1.4.2 call back.

Fix

#onClose queues the check itself with process.nextTick, where the listener was added. No socket listener is involved.
On a plaintext close with an error the check decides at once and emits one tick later. 'clientError' stays ahead of the server's 'close', as in Node.
Verified: test/js/node/http/node-http-server-close-drain.test.ts (26 rows in one fixture, 21 differ with src/ at main). Other suites: Notes.
Self-reviewed: 20 concerns raised, 16 addressed. Not taken: the owner slot (3) and listen() before the last close is delivered (1). Both are separate changes.

Background

emitCloseServer emits the server's 'close' when the listener is closed and no connection is tracked.
Node counts a connection down in Socket.prototype._destroy and queues the server's 'close' there.
Considered counting down first in #onClose: getConnections() then reads 0 inside a 'readable' listener at the peer's FIN, where Node reads 1.

Downsides

Order: the server's 'close' now comes before the last socket's 'close' when the listener's own close was already delivered. That is Node's order. 1.4.3 has the reverse, and one test asserted it.
Cost: #onClose bytecode grows from 1149 to 1198 bytes. instructions:u is not measured: no perf or valgrind in the build container.
Still withheld, as on main: three shapes in Notes.

Notes

How it was found. By probing the lifecycle code of #43557. No user reported these shapes. Issue #45095 has a similar title and a different cause: its repro also waits on Node v26.3.0 (a half-open upgraded socket that nothing ends), and this PR does not change it.

The rows (test/js/node/http/node-http-server-close-last-connection-fixture.js, one process, each step follows an event or a round trip). Node v26.3.0 runs the same file. With src/ at main, 21 of the 26 rows differ from this branch, and 17 of them never get the callback. Bun 1.4.3 prints the same lines as main.

Row	This PR	main and Bun 1.4.3
a response `'close'` listener throws (http, https)	server close, close callback, response close, uncaught boom	response close, uncaught boom
a socket `'close'` listener throws	server close, close callback, uncaught boom	uncaught boom
the `'close'` listener of an upgraded socket throws	server close, close callback, uncaught boom	uncaught boom
the `'close'` listener of a socket that sent one byte throws	uncaught boom, server close, close callback (Node: the uncaught error is last)	uncaught boom
`server[Symbol.asyncDispose]()` waits and a socket `'close'` listener throws	server close, uncaught boom, disposed (Node: disposed, then the uncaught error)	uncaught boom
an `'aborted'` listener removes the socket's `'close'` listeners	server close, close callback	nothing
the program's `socket.emit` swallows `'close'`	server close, close callback	nothing
the `'error'` listener of a socket destroyed with an error throws	uncaught boom, server close, close callback	uncaught boom
`closeAllConnections()`, `closeIdleConnections()` or the peer closes the idle last connection, and its `'close'` listener throws (3 rows)	server close, close callback, uncaught boom	uncaught boom
`closeIdleConnections()` and then `socket.destroy()`	uncaught boom, server close, close callback (Node: the uncaught error is last)	the same
a socket `'end'` listener removes every listener of the socket	server close, close callback	nothing
a socket `'error'` listener removes the `'close'` listeners at the peer's reset	socket error ECONNRESET, server close, close callback	socket error ECONNRESET
the peer ends the idle last connection (http, https)	socket end, server close, close callback, socket close	socket end, socket close, server close, close callback
`close()` itself closes the idle last connection	socket close, server close, close callback (Node: socket close is last)	the same
a tunnel that is idle after the peer's FIN is destroyed	server close, close callback	the same
the response is destroyed with an error (http)	clientError, server close, close callback	the same
the response is destroyed with an error (https)	server close, close callback, clientError	clientError, server close, close callback
the peer resets a connection that sent part of a request head (http)	clientError ECONNRESET, server close, close callback	the same
the same over https	server close, close callback, clientError ECONNRESET	clientError ECONNRESET, server close, close callback
a `'clientError'`, socket `'error'` or socket `'close'` listener listens again (3 rows)	server close, close callback, listening again	listening again

This branch prints Node's line in 22 of the 26 rows. The 4 others are marked above. In each of them the socket's 'close' comes earlier than in Node: Node emits it in a later turn of the loop, Bun in a tick.

Each clause of the fix has a row that fails without it (checked by swapping the generated JS): without || this.#closeError 2 rows change, without errored || 3, without !this.encrypted 2, with no error path at all 5, and with the decision taken on the second tick the 3 "listens again" rows.

The test that changed. node-http.test.ts, "waits for an active keep-alive connection to close before server.close() completes", asserted that the socket's 'close' comes before the close callback. Node v26.3.0 prints server 'close' | close callback | socket close for that scenario (3 of 3 runs), so the old assertions fail on Node. The test now asserts Node's order and waits for the server socket's 'close' before it reads the events.

The order rule. The server's 'close' comes before the last socket's 'close' only when the native close of the listener was already delivered when that connection's close handler runs. The socket's 'close' is still first when a request was pending at the native close, when close() itself sweeps the idle connection, and on a plaintext close that carries an error.

Measurements (debug build of e40a58ad87, main's generated JS against this PR's on the same binary).

JSLexicalEnvironment per 1000 connection closes, GC off (bun:jsc heapStats): main 12001 and 12001, PR 11001 and 11001. #onClose has 1 create_lexical_environment and 1 new_func_exp on main, 0 and 0 here.
Per connection with no close() pending: 1 add, 1 delete and 1 size read on the tracked set, on both. Per drain: once("close") registrations 1 on main, 0 here. One emitCloseServer tick on both.
socket.listenerCount("close") inside the last emission with close() pending: main 3, PR 2, Node 3. Not pending: main 2, PR 2.
#onClose bytecode: 230 instructions and 1149 bytes on main, 238 and 1198 here. emitCloseServer (87 instructions, 381 bytes) becomes takePendingClose (83, 364) plus emitCloseServer (11, 49).
The production bundle of _http_server.js: 98485 to 98815 bytes (+330).
Native files changed: 0. $newRustFunction bindings in _http_server.ts: 2 on both.
instructions:u: not measured. perf and valgrind are not installed in the build container, and no release build of both sides was made.
Node tests: +0. Of the 504 vendored test-http-* and test-https-* files, 499 pass on this cut. The 5 others (test-http-abort-queued.js, test-http-agent-keepalive.js, test-http-client-timeout-option.js, test-http-outgoing-end-cork.js, test-https-timeout.js) fail the same way with main's JS on this debug build.

Suites run on the debug build with this cut: node-http-server-close-drain.test.ts 31 pass (with src/ at main 30 pass, 1 fail: the new test). node-http.test.ts 290 pass, 2 fail. node-http-server-abort-events.test.ts 105 pass. node-http-server-socket-end-drain.test.ts 9 pass. node-http-server-timeouts.test.ts 16 pass. bun lint, bun fmt --check, tsc -p src/js/tsconfig.json. On the first cut node-http-connect.test.ts, node-http-upgrade-body.test.ts, node-http-with-ws.test.ts, node-https-server.test.ts, node-http-backpressure.test.ts, node-http-uaf.test.ts and ws.test.ts were run too. Every failure in these runs is a 5 s timeout of a test that starts a debug bun process, and the same tests time out with main's JS on that binary.

Still withheld, as on main.

A socket 'readable' listener that throws at the peer's FIN: the throw leaves #onClose before the count goes down. Open PR node:http: emit 'close' on req.socket with hadError, also when its 'error' emit throws #45017 puts a catch on those two statements and has the row.
A socket that the program emits as a 'connection' of a second http.Server: its close is counted on the second server, and the first keeps getConnections() 1. Older than node:http: the server follows Node (request body, framing, response finish, lifecycle) #43557 (1.4.2 prints connections 1). It needs the accepting server in its own slot, which authorized and authorizationError should read too, and open PRs node:http: closeIdleConnections() reads req.complete, and a destroyed request sets it #44310 and fix(node:https): wrap injected raw connections with TLS #42594 touch the same lines. A separate change.
close(cb), then destroy the last connection and listen() before that connection's close is delivered (the same tick, a microtask or a nextTick): the callback waits for the next close(). Node decides in the _destroy frame. Doing the same changes when getConnections() counts a destroyed connection. The same gate withholds the callback when a request was pending at the native close and a listener of the socket listens again before the listener's own close is delivered. A separate change.

Not changed here. The gates in takePendingClose (the body of the old emitCloseServer), close(), _destroy, every native file, and the response-'close' emitter. close(cb) on a server that is not listening still emits no 'close' (older than #43557).

First cut of this PR. It counted the connection down at the head of #onClose, wrapped the statements after it in try/finally, and kept the accepting server in a private field. A review of that diff found that the head count-down changes getConnections() inside a 'readable' listener at the peer's FIN from 1 (Node, main) to 0, that #45017 already fixes the one row it bought, and that a private field cannot be set by the re-home loop of #44310. This cut drops all three.

Neighbours. #45017 changes how this socket emits 'error' and 'close'. With it the server's 'close' on a plaintext error close lands between the two, as in Node. The earlier PRs #35837 and #35844 queued the same direct tick before #43557 replaced it with the listener.

… handler, not from a socket 'close' listener

… keep-alive test asserts Node's order

robobun · 2026-10-14T17:43:29Z

^{Updated 12:01 PM PT - Oct 19th, 2026}

✅ @robobun, your commit 3dd502d5a4059cd154bfa198140ca05459723824 passed in Build #128928! 🎉

🧪 To try this PR locally:

bunx bun-pr 45257

That installs a local version of the PR into your bun-45257 executable, so you can run:

bun-45257 --bun

robobun · 2026-10-14T17:43:36Z

Status: ready for review. CI is green on 3dd502d5a4 (build 128928), and every review thread is resolved. The description has the details and what is left for separate changes.

How to reproduce the bug: run bun test/js/node/http/node-http-server-close-last-connection-fixture.js from this branch with Bun 1.4.3 or with a build of main. The output is one JSON object with 26 rows. In 17 of them the server's close callback (or disposed) never comes. Node v26.3.0 runs the same file and calls back in every row. This branch calls back in every row and prints Node's line in 22 of them. The test file gives Node's line for the other 4.

The rows that match the shapes this was first seen with are a response 'close' listener throws, a socket 'close' listener throws, the 'close' listener of an upgraded socket throws, and the 'close' listener of a socket that sent one byte throws.

…istener, the count stays where it was

…h Node's line where it differs

coderabbitai · 2026-10-15T15:19:55Z

Walkthrough

The server-close path now checks pending close state through a separate helper and defers close emission after plaintext socket errors. New HTTP and HTTPS tests cover close-event ordering across connection scenarios. The keep-alive test expects the server close callback before the server socket’s close event.

Changes

HTTP server close handling

Layer / File(s)	Summary
Pending close checks and scheduling `src/js/node/_http_server.ts`	The pending close readiness and state-reset logic moves to `takePendingClose`. Plaintext socket errors defer the close check by one tick. When the last tracked socket closes during a pending server close, the code schedules the check directly.
Close-event scenario tests `test/js/node/http/node-http-server-close-last-connection-fixture.js`, `test/js/node/http/node-http-server-close-drain.test.ts`, `test/js/node/http/node-http.test.ts`	A subprocess fixture records event sequences for HTTP and HTTPS close scenarios. The test harness checks those sequences, and the keep-alive test expects the close callback before the server socket’s `close` event.

Suggested reviewers: jarred-sumner

Priority: ➖ Normal

Merge Risk: 🔵 Low · up to 3dd50

The remaining concern is a test-specific timeout that conflicts with repository guidance. It is localized and does not indicate a product behavior regression, so merge risk is low.

Pre-merge checks: 4

Check name	Status	Explanation
Title check		The title clearly describes the main change: queueing the server close check from the connection close handler instead of a socket close listener. It is specific, though somewhat long.
Description check		The description explains the problem, the fix, and how the author verified it. It does not use the template’s exact headings, but it provides the required information in detail.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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Review comments at
@test/js/node/http/node-http-server-close-last-connection-fixture.js:
- Line 27: Remove the DEADLINE_MS-based setTimeout from the fixture so it does
not terminate valid runs based on elapsed time; rely on the parent test runner
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📒 Files selected for processing: 4

src/js/node/_http_server.ts
test/js/node/http/node-http-server-close-drain.test.ts
test/js/node/http/node-http-server-close-last-connection-fixture.js
test/js/node/http/node-http.test.ts

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claude

Nothing blocking. The comments below are optional suggestions. There is no need to push a fix for them before merging.

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Nothing blocking. The comments below are optional suggestions. There is no need to push a fix for them before merging.

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Inline comments:
Review comments at @test/js/node/http/node-http-server-close-drain.test.ts:
- Line 1023: Update the test’s third bun:test argument to remove the per-test
timeout, and adjust the fixture startup or test flow so it completes within
Bun’s 5,000 ms default, including on local ASAN/debug builds. Preserve the
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robobun added 4 commits October 14, 2026 14:32

node:http: queue the server 'close' check from the connection's close…

76afb97

… handler, not from a socket 'close' listener

test: rows for the last connection of a pending server.close(cb); the…

84f618f

… keep-alive test asserts Node's order

test: two rows compare in any order, the error rows destroy the response

94becd8

test: one fixture process for the last-connection rows

79f4ce6

robobun assigned Jarred-Sumner Oct 14, 2026

github-actions Bot added the claude label Oct 14, 2026

robobun added 2 commits October 15, 2026 14:07

node:http: cut the change in place: the server's check replaces the l…

6696148

…istener, the count stays where it was

test: 26 rows for the last connection, pinned to what Bun prints, wit…

2f3ce9e

…h Node's line where it differs

github-actions Bot reviewed Oct 15, 2026

View reviewed changes

Comment thread src/js/node/_http_server.ts Resolved

github-actions Bot reviewed Oct 15, 2026

View reviewed changes

Comment thread src/js/node/_http_server.ts Resolved

node:http: one-line comments with the Node permalinks

568532a

robobun marked this pull request as ready for review October 15, 2026 15:12

coderabbitai Bot reviewed Oct 15, 2026

View reviewed changes

Comment thread test/js/node/http/node-http-server-close-last-connection-fixture.js Resolved

claude Bot reviewed Oct 15, 2026

View reviewed changes

Comment thread src/js/node/_http_server.ts Resolved

This was referenced Oct 19, 2026

node:http: release the earlier http.Server under bun --hot #46039

Open

node:http: a 'connect' or 'upgrade' socket keeps its unread bytes when the connection closes #46067

Open

test: the fixture has no deadline of its own

3dd502d

claude Bot reviewed Oct 19, 2026

View reviewed changes

Comment thread test/js/node/http/node-http-server-close-drain.test.ts Resolved

coderabbitai Bot reviewed Oct 19, 2026

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Comment thread test/js/node/http/node-http-server-close-drain.test.ts Resolved

dylan-conway mentioned this pull request Oct 22, 2026

node:http: a paused upload behind a sent response does not hold the event loop #46424

Open

Jarred-Sumner mentioned this pull request Oct 22, 2026

http: consolidate the open fetch, Bun.serve, node:http, node:http2 and HTTP/3 pull requests #46528

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node:http: queue the server 'close' check from the connection's close handler, not from a socket 'close' listener - #45257

node:http: queue the server 'close' check from the connection's close handler, not from a socket 'close' listener#45257
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