node:http2: destroy streams before the native sweep in session teardown by robobun · Pull Request #42717 · oven-sh/bun

robobun · 2026-09-14T13:43:54Z

Problem

A session teardown emits 'drain' on a stream whose write is blocked on flow control. Then write() always returns true. A producer parked on 'drain' wakes up and writes its whole source into the dead stream: 'drain' AFTER destroy: 1, 67043328 bytes accepted. Node v26.3.0: 0 and 0.
The native sweep (emitErrorToAllStreams, emitAbortToAllStreams) drops the queued DATA frames and calls their write callbacks with no error (clean_queue, src/runtime/api/bun/h2_frame_parser.rs:1895). The JS stream is destroyed one tick later, so afterWrite sees a live stream.
Paths in src/js/node/http2.ts: ClientHttp2Session.destroy() (5875), the server's socket close (4320), the server's error GOAWAY (4292).

Fix

Each path destroys its streams before the sweep, like node's closeSession and socketOnClose. ServerHttp2Session.destroy() does so since node:http/https/http2: raise Node v26.3.0 compat to ~94%, sync the upstream suites, and fix the Windows/macOS transport-layer teardown bugs they exposed #32488. Errors and rstCode stay the same.
The server socket-close handler uses the client's sequence: close(CANCEL), then destroy(). emitAbortToAllStreams has no caller left and is removed.
A stream that session.destroy() destroys skips _final. On main the server sent DATA(END_STREAM) after its GOAWAY, so the peer read a cut response as complete.
Verified: test/js/node/http2/node-http2-session-destroy-backpressure.test.ts (main fails 4 of 5, node passes 5). All of test/js/node/http2/, the 279 vendored test-http2-* tests, grpc-js.

Background

Flow control: a sender can have one window (65535 bytes by default) of DATA in flight per stream until the peer sends WINDOW_UPDATE. Bun queues the rest natively and keeps the write callback with the frame.
Writable emits 'drain' from afterWrite when a write callback succeeds and the stream is not ending or destroyed.
_final is where Http2Stream writes the empty DATA(END_STREAM) frame.

Notes

History. This replaces #33606, which the stale-PR cleanup closed (conflicts with main). The bug is still live on canary 1.4.3 b99371011 and on main 09bb546305. A first attempt in #33606 passed an error from native clean_queue to the write callback. clean_queue also serves stream.close(), a received RST_STREAM and the socket-abort paths, where the stream is still live. The error reached errorOrDestroy there and raised uncaught 'error' events (test-http2-cancel-while-client-reading.js, test-http2-respond-with-file-connection-abort.js). This PR does not change clean_queue.

Measured, {drains, accepted} with a budget of 32 writes in the 'drain' listener (node v26.3.0 is 0, 0 in every row):

path	main	this PR
client `session.destroy()`	1, 32	0, 0
server, peer closes the socket	1, 32	0, 0
server, peer sends GOAWAY(INTERNAL_ERROR, last stream id 0)	1, 32	0, 0
server `session.destroy()`	0, 0	0, 0

Wire and events for session.destroy() on an idle open stream with no 'error' listener (frames the peer receives after the call):

	node	main	this PR
client	`aborted close`, GOAWAY	`aborted close`, GOAWAY	`aborted close`, GOAWAY
server	`aborted close`, GOAWAY	`aborted finish close`, GOAWAY DATA(END_STREAM)	`aborted close`, GOAWAY

The client pre-pass alone would add the finish and the DATA(END_STREAM) to the client row: _destroy clears the destroyed flag around end() so that _final runs, and with the parser still attached _final writes the frame. With an error the writable is already errored and _final does not run, so only streams without an 'error' listener show it. The SessionDestroyed bit makes _destroy call end() with destroyed set, which is what node's _destroy does. #33380 (open) makes every _destroy() and close(code) skip the END_STREAM. It subsumes this bit if it lands.

Server socket close. For an idle response stream the events are now aborted finish close with rstCode 8, the same as node. Main gives aborted close.

Server error GOAWAY. The handler called emitErrorToAllStreams(errorCode) and then destroy(sessionError, NO_ERROR). That line is older than the pre-pass that #32488 added to destroy(). destroy() sweeps with kGoawayCode precedence, so each stream keeps the same error and rstCode without it. The client's GOAWAY handler has no such line.

Skipped streams. The client pre-pass skips streams that are already marked closed, like the native sweep skips CLOSED streams. Without the skip, streams that completed normally got ERR_HTTP2_STREAM_CANCEL (should be destroyed after destroy and wantTrailers should work in node-http2.test.js). A non-numeric code makes the native sweep throw. The pre-pass does not run for it, so the retry still finds the streams (h2-conformance.test.ts, "session teardown rejects a non-numeric error code").

Stream 'close' now comes before session 'close' on a client session.destroy(), as in node. Before: aborted, session close, error, close. Now: aborted, error, close, session close.

Not changed, on purpose.

request({ signal }): an abort with a blocked write still gives 1, 32. The native abort listener runs before the JS one, so the ordering fix cannot apply. It needs the signal to stay in JS. Handed to a separate change.
A peer RST_STREAM on a createConnection transport was reported by review as another live path. On a native socket I measured 0, 0 on main.
The write callback of a dropped frame still reports success. Node reports ECANCELED. That is safe to change only when every sweep destroys its streams first.
An open client stream gets ERR_HTTP2_STREAM_CANCEL and rstCode 8 on a plain session.destroy(). Node gives no error and rstCode 0.

Suites on the debug+ASAN build. test/js/node/http2/: node-http2.test.js 387 pass, h2-conformance.test.ts 70, node-http2-client-close.test.ts 69, and the eight smaller files. All 279 vendored test-http2-* and test-diagnostics-channel-http2-* files. grpc-js: 16 suites pass, test-client (3), test-outlier-detection (2) and test-tonic (1) fail the same way without this change. undici-h2 11, wpt-h2 20. The http2 cases in AsyncLocalStorage.test.ts. h2-conformance.test.ts "stream release after a queued END_STREAM" fails in some runs on the debug build with and without this change (#42357).

Self-reviewed: 14 concerns raised, 11 addressed in the diff, 3 named above as excluded.

[human-review] gate passed · iteration 7 · 4 files touched

fails on main (without fix)

ASAN without fix: 4 FAILED
$ BUN_DEBUG_QUIET_LOGS=1 bun scripts/build.ts --profile=debug --quiet test "--reporter=junit" "--reporter-outfile=/tmp/pr_gate.xml" "test/js/node/http2/node-http2-session-destroy-backpressure.test.ts"
bun test v1.4.3 (b99371011)

test/js/node/http2/node-http2-session-destroy-backpressure.test.ts:
187 | 
188 |       const closed = closedAndSettled(stream);
189 |       session.destroy();
190 |       await closed;
191 | 
192 |       assert.deepStrictEqual({ backpressured, ...seen }, { backpressured: true, drains: 0, accepted: 0 });
                   ^
AssertionError: Expected values to be strictly deep-equal:
+ actual - expected

  {
+   accepted: 32,
-   accepted: 0,
    backpressured: true,
+   drains: 1
-   drains: 0
  }

 generatedMessage: true,
     actual: {
  backpressured: true,
  drains: 1,
  accepted: 32,
},
   expected: {
  backpressured: true,
  drains: 0,
  accepted: 0,
},
   operator: "deepStrictEqual",
       diff: "simple",
       code: "ERR_ASSERTION"

      at /workspace/bun/test/js/node/http2/node-http2-session-destroy-backpressure.test.ts:192:14
      at node:test:1781:26
      at executeTestNode (node:test:1785:63)
      at processTicksAndRejectio
... (truncated)

release without fix: 4 FAILED
bun test v1.4.3-canary.1 (b99371011)

test/js/node/http2/node-http2-session-destroy-backpressure.test.ts:
187 | 
188 |       const closed = closedAndSettled(stream);
189 |       session.destroy();
190 |       await closed;
191 | 
192 |       assert.deepStrictEqual({ backpressured, ...seen }, { backpressured: true, drains: 0, accepted: 0 });
                   ^
AssertionError: Expected values to be strictly deep-equal:
+ actual - expected

  {
+   accepted: 32,
-   accepted: 0,
    backpressured: true,
+   drains: 1
-   drains: 0
  }

 generatedMessage: true,
     actual: {
  backpressured: true,
  drains: 1,
  accepted: 32,
},
   expected: {
  backpressured: true,
  drains: 0,
  accepted: 0,
},
   operator: "deepStrictEqual",
       diff: "simple",
       code: "ERR_ASSERTION"

      at /workspace/bun/test/js/node/http2/node-http2-session-destroy-backpressure.test.ts:192:14
      at node:test:1445:26
      at executeTestNode (node:test:1448:63)
      at processTicksAndRejections (native:7:39)
(fail) a flow-control-blocked write gets no 'drain' and the stream accepts no more writes > when the client session is destroyed [38.81ms]
205 |       closedAndSettled(stream)
... (truncated)

passes on PR (with fix)

ASAN with fix: all passed
$ BUN_DEBUG_QUIET_LOGS=1 bun scripts/build.ts --profile=debug --quiet test "--reporter=junit" "--reporter-outfile=/tmp/pr_gate.xml" "test/js/node/http2/node-http2-session-destroy-backpressure.test.ts"
bun test v1.4.3 (b99371011)

test/js/node/http2/node-http2-session-destroy-backpressure.test.ts:
(pass) a flow-control-blocked write gets no 'drain' and the stream accepts no more writes > when the client session is destroyed [713.89ms]
(pass) a flow-control-blocked write gets no 'drain' and the stream accepts no more writes > when the server session's socket closes [282.16ms]
(pass) a flow-control-blocked write gets no 'drain' and the stream accepts no more writes > when the server session receives a GOAWAY with an error code [107.22ms]
(pass) session.destroy() does not end an open stream on the wire > client session [81.54ms]
(pass) session.destroy() does not end an open stream on the wire > server session [69.73ms]

 5 pass
 0 fail
Ran 5 tests across 1 file. [4.24s]
__F:0:S:0

release with fix: all passed
$ bun scripts/build.ts --profile=release
[configured] bun-profile → bun (stripped) in 830ms (unchanged)
ninja: Entering directory `/workspace/bun/build/release'
[1/127] gen generated_host_exports.rs
generated_host_exports.rs: 122 exports (host=5, lazy=10, generic=107, rust=0); 243 extern-C blocks audited
[2/127] gen ZigGeneratedClasses.{cpp,h,rs}
Found 2 classes from /workspace/bun/src/jsc/resolve_message.classes.ts
  - ResolveMessage (15 fields)
  - BuildMessage (10 fields)
Found 1 classes from /workspace/bun/src/runtime/api/Archive.classes.ts
  - Archive (4 fields, 1 class fields)
Found 2 classes from /workspace/bun/src/runtime/api/BunObject.classes.ts
  - ResourceUsage (8 fields)
  - Subprocess (20 fields)
Found 1 classes from /workspace/bun/src/runtime/api/cron.classes.ts
  - CronJob (5 fields)
Found 3 classes from /workspace/bun/src/runtime/api/filesystem_router.classes.ts
  - FileSystemRouter (5 fields)
  - FrameworkFileSystemRouter (2 fields)
  - MatchedRoute (8 fields)
Found 1 classes from /workspace/bun/src/runtime/api/Glob.classes.ts
  - Glob (5 fields)
Found 1 classes from /workspace/bun/src/runtime/api/h2.classes.ts
  - H2FrameParser (31 fields)
Found 
... (truncated)

diff hotspot

src/js/node/http2.ts                               |  37 ++-
 src/runtime/api/bun/h2_frame_parser.rs             |  39 ---
 src/runtime/api/h2.classes.ts                      |   4 -
 ...node-http2-session-destroy-backpressure.test.ts | 286 +++++++++++++++++++++
 4 files changed, 315 insertions(+), 51 deletions(-)

gate history · 1 passed · 0 rejected · iteration 7

evidence per changed file

file                                                      reads  edits  tests
src/js/node/http2.ts                                         27     24     29
src/runtime/api/bun/h2_frame_parser.rs                       19      5     29
src/runtime/api/h2.classes.ts                                 1      1     29
…e/http2/node-http2-session-destroy-backpressure.test.ts      3      8     29

A session teardown ran the native stream sweep while the JS streams were still live. The sweep drops DATA frames that are queued behind flow control and settles their write callbacks with no error, so the Writable emitted 'drain'. A producer parked on 'drain' woke up, and every later write() reported success because the native handle was gone. - ClientHttp2Session.destroy() destroys its open streams first, as the server session and node do. It goes through emitStreamErrorNT, so each stream gets the same error and rstCode as before. - ServerHttp2Session's socket-close handler closes and destroys the streams in JS, like the client session and node's socketOnClose. The native abort sweep it replaced has no caller left and is removed. - The server's error-GOAWAY handler no longer sweeps before destroy(), which does the same work after it has destroyed the streams. - A stream that session.destroy() destroys ends its writable without _final. The server session put DATA(END_STREAM) on the wire behind the GOAWAY and emitted 'finish' for an open response.

robobun · 2026-09-14T13:44:13Z

^{Updated 7:35 AM PT - Sep 14th, 2026}

❌ @robobun, your commit a2c5363 has 2 failures in Build #115518 (All Failures):

test/js/bun/spawn/spawn-pipe-leak.test.ts - code 1 on 🐧 13 x64
test/bake/deinitialization.test.ts - pid 5716 segmentation fault at address 0x0 on 🪟 2019 x64

🧪 To try this PR locally:

bunx bun-pr 42717

That installs a local version of the PR into your bun-42717 executable, so you can run:

bun-42717 --bun

robobun · 2026-09-14T13:44:22Z

Status: reproduced, fix in this PR. The diff is green, CI is red on tests this PR does not touch.

How to reproduce: a raw h2c peer completes the SETTINGS exchange and never sends WINDOW_UPDATE. The bun side writes 65535 + 32768 bytes on one stream, so 32 KiB stays queued behind flow control with the write callback held. A 'drain' listener writes until write() returns false (budget 32). Then the session is torn down.

bun bd test test/js/node/http2/node-http2-session-destroy-backpressure.test.ts on main 09bb546305: 4 of 5 fail, each with drains: 1, accepted: 32 (client session.destroy(), server socket close, server error GOAWAY), or with finish and DATA(END_STREAM) after the GOAWAY (server session.destroy()).
With this PR: 5 of 5 pass.
node --experimental-strip-types --test on the same file with node v26.3.0: 5 of 5 pass.

CI: every node:http2 test passes on every lane in builds 115515 and 115518. The red tests do not load node:http2, and each one also fails on other branches:

test/js/bun/spawn/spawn-pipe-leak.test.ts (debian 13 x64): fails or needs retries in builds 115507, 115505, 115480, 115468, 115461, 115446, 115441, 115438, 115433, 115426, 115425.
test/bake/deinitialization.test.ts (segmentation fault on Windows 2019 x64): the same crash in builds 115477, 115429, 115426.
test/cli/inspect/inspect.test.ts (one segmentation fault on Windows 2019 x64 in 115515): it did not repeat in 115518.

coderabbitai · 2026-09-14T13:51:08Z

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test/js/node/http2/node-http2-session-destroy-backpressure.test.ts

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Walkthrough

HTTP/2 session destruction now cancels streams synchronously, avoids late writable events and END_STREAM, and routes GOAWAY and socket-close handling through stream teardown. The native abort-all-streams API was removed and covered by client and server regression tests.

Changes

HTTP/2 teardown

Layer / File(s)	Summary
Session-driven stream teardown `src/js/node/http2.ts`	Session destruction marks streams, cancels open client streams, validates reset codes, and prevents writable finalization during session teardown.
Socket and GOAWAY teardown paths `src/js/node/http2.ts`, `src/runtime/api/h2.classes.ts`, `src/runtime/api/bun/h2_frame_parser.rs`	GOAWAY errors use session destruction. Socket closure sends `NGHTTP2_CANCEL` before destroying streams. The native abort-all-streams method was removed.
Teardown regression coverage `test/js/node/http2/node-http2-session-destroy-backpressure.test.ts`	Tests cover blocked writes, stream events, subsequent writes, `drain`, `END_STREAM`, client destruction, server socket closure, and GOAWAY handling.

Suggested reviewers: cirospaciari

Priority: ➖ Normal

Merge Risk: 🟡 Moderate · up to 816d7

Session teardown can still emit a late drain event for a closed, flow-control-blocked stream, potentially allowing additional writes after teardown. Resolve this path before merging.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
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Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly summarizes the primary change: destroying HTTP/2 streams before the native sweep during session teardown.
Description check	✅ Passed	The description explains the problem, fix, affected teardown paths, behavior changes, and verification results. It does not use the template headings exactly, but it provides the required information …

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Inline comments:
In `@src/js/node/http2.ts`:
- Line 2293: Update the session teardown stream handling around the
destroyed/closed guard to skip streams that are destroyed or already marked
NativeClosed, but destroy JavaScript-closed streams that are not natively closed
before emitErrorToAllStreams() performs native cleanup.

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robobun assigned Jarred-Sumner Sep 14, 2026

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node:http2: error pending write callbacks when a stream is torn down #33606

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node:http2: shorten the new comments to one line each

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node:http2: keep the data that arrived before a peer's RST_STREAM(NO_ERROR) #43754

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node:http2: destroy streams before the native sweep in session teardown - #42717

node:http2: destroy streams before the native sweep in session teardown#42717
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