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… module-graph-isolation.test.ts
The fixture dials-after-it-was-disposed.mjs counted the connections its
listener accepted 10 setImmediate turns after the host's own
Bun.connect() resolved. A connect() completes on the SYN-ACK. The
listener gets the connection one packet later. On a busy macOS x64 host
that packet arrives after the 10 turns, so the fixture printed
{"arrivedFromTheGraph":-1}.
The host now dials after the microtask the graph left has run, once
with Bun.connect() and once with fetch(), the two threads that dial.
The fixture counts when the listener has both of them. No turn count
is left. The expected output does not change.
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Updated 1:09 PM PT - Oct 18th, 2026
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WalkthroughThe module graph isolation fixture records accepted connections’ remote ports and detects host fetches. It waits for both a host TCP connection and an HTTP fetch before reporting the connection count after subtracting those arrivals. ChangesModule graph isolation test
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The title clearly describes the main test change: waiting for the host's dials at the listener in the module graph isolation test. |
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Review comments at @test/js/bun/module-graph/module-graph-isolation.test.ts:
- Line 977: Update the socket data handler in the Bun.listen fixture to buffer
request-line bytes per socket across callbacks, then set theHostsFetchArrived
once the accumulated data starts with the expected request line. Preserve the
existing behavior for requests received in a single callback.
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test/js/bun/module-graph/module-graph-isolation.test.ts
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…f them fails The fixture polled once per turn for the host's socket and fetch. It now awaits a promise for each, resolved by the listener. The request line of the fetch is buffered per socket, so a line that arrives in two reads still matches. A fetch that fails or gets an answer rejects, and so does a socket that closes or errors, so the fixture exits with the reason and does not wait for the kill after 30 s.
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LGTM — the second commit replaces the unbounded setImmediate poll with awaited promises and wires every failure path to reject, which resolves what I raised on the earlier revision.
What was reviewed:
- The port-matching handshake for the host's Bun.connect:
theHostsPortstarts at -1 so no listener-side arrival matches early, and both the clientopen(viaarrived.includes) and the listeneropencan resolve it, so either ordering of the twoopencallbacks works. - Failure wiring: connect
close/error/promise rejection and fetch resolve-or-reject all reject the awaited promise, so a stalled host dial now surfaces as an unhandled rejection with a message rather than a 30 s SIGKILL with empty stdout. - The fetch sentinel buffers chunks into
socket.databefore theGET /the-hostsprefix check, so a split request line cannot be missed; the graph's own fetch/FetchSession/http.get targets are/, so they cannot satisfy it. arrived.length - 2is consistent with the consuming test's{"arrivedFromTheGraph":0}expectation at line 3673; no port hardcoding, no external hosts,runsFixturestill drains stdout concurrently withexited.
Extended reasoning...
The PR changes only the inline fixture dials-after-it-was-disposed.mjs in test/js/bun/module-graph/module-graph-isolation.test.ts (+24/-6 across two commits), swapping a fixed 10-turn count for two host-side sentinel dials awaited at the listener; no runtime code, no security-sensitive surface, and the file is not covered by CODEOWNERS. The second commit directly addressed the only inline concern I posted on the previous revision (unbounded poll and swallowed fetch rejection), and the one third-party review is a non-blocking COMMENTED state on a line that the later commit rewrote. The change is small, self-contained, and the expected output of the consuming test is unchanged, which decided approve.
Problem
test/js/bun/module-graph/module-graph-isolation.test.tsis red on macOS 14 x64. The fixturedials-after-it-was-disposed.mjsprints{"arrivedFromTheGraph":-1}. It failed every retry in 7 builds, 126542 among them.setImmediateturns after theBun.connect()of the host resolves.-1means the listener had not accepted that dial yet.Fix
Bun.connect()(JS thread) andfetch()(HTTP thread).-1in 20 of 20 runs, this PR0in 20 of 20.Background
connect()completes on the SYN-ACK. The listener can accept only after the client's ACK, one packet later.Bun.connect()dial. With the ACK held back and the graph not disposed, that prints0in 4 of 20 runs.Notes
The cause, from the code
Bun.connect()resolves on the writable event of the client fd (src/runtime/socket/socket_body.rs:1625). Nothing on that path waits for the listener.open()of the listener runs only when a poll reports the listen fd readable (packages/bun-usockets/src/loop.c:515).setImmediateturns. So the listener had the rest of one poll batch and 9 more polls to become readable. On Linux x64 (release) 10000 plain turns take 9 to 12 ms, so the 10 turns take about 10 µs.arrived === 0, soarrived - 1is-1.Bun.connect()before the microtask of the graph runs. A probe printshost: Bun.connect() calledbeforegraph: leftover microtask runs. The comment in the fixture says "made afterwards".Reproduction on Linux
The kernel here has no
netem. A private network namespace with oneiptablesrule drops each loopback TCP segment that has ACK without SYN for the first second. The client still connects on the SYN-ACK. The listener gets the connection when a retransmission arrives after the rule is gone. This is a stand-in for a late ACK. It also changes the order in which connections complete, which a late loopback does not.Three fixtures: the one of main, the smaller fix (wait for the
Bun.connect()dial at the listener, same 10 turns), and this PR.0in 30 of 300in 30 of 300in 100 of 100-1in 20 of 200in 10 of 100in 20 of 2041in 10 of 1041in 10 of 1041in 20 of 20-1in 5 of 541in 12,19in 4,0in 4 of 2041in 20 of 20fetch()goes outFetchSessionfetch goes outnet.connect,http.get,WebSocket,RedisClientorBun.SQLgoes out"Goes out" is one dial of that kind that the host makes from a microtask queued next to the one of the graph. It stands for a dial of the disposed graph that the runtime did not stop.
fetch()andFetchSessiondial from the HTTP thread. On main the 10 turns decide whether such a dial is counted.What the order claim rests on
dispose(). It does not cover a dial that a disposed graph starts later than that. The old fixture gave such a dial its 10 turns, about 10 µs. I tested no case of a later start.Failures of the dials of the host
0in 10 of 10 runs.HTTP_PROXYset to a closed port: exit 1 at once withECONNREFUSED.HTTP_PROXYset to a server that answers 502: exit 1 at once withthe host's fetch did not go to the listener: it was answered with status 502.Why the socket of the host stays open
The old fixture called
socket.end()in theopen()of the client. The new fixture matches the dial by the port the listener reads in itsopen(). A client that closed before the accept would make that depend on how the platform reports a peer that is already gone.What I ran
1.4.4-canary.1+ed680823c, 11 commits behind main), whole file with--timeout=90000as the CI runner passes it: 25 of 25 runs pass, and the changed case passes in 25 of 25. Earlier batches of 25 had 2 or 3 runs that failed in other cases, with the file of main too ("background work under way when its graph is disposed does not settle into it", "its node:perf_hooks observer is disconnected"). This change does not touch those.bun bd test), the changed case alone on an idle machine: 6 of 6 runs pass, in 2.1 to 4.2 s. The default limit is 5 s, so the margin is small. The fixture alone takes 1.9 to 2.6 s with this change and 1.9 to 2.1 s on main (10 runs each, in turns).:darwin: any x64and passed at the first attempt: 413 pass, 0 fail, 5.01 s.:darwin: any x64jobs started between 09:39 and 13:08 UTC. So this run shows that the fixture runs on that lane. It does not show the fixture on a host in the state that made the old one fail. No run of mine covers that.Sightings
Builds 126487, 126523, 126529, 126533, 126538, 126542 and 126546 are red on
:darwin: any x64with this output. Build 126833 shows it and passes on a retry. I found it on no other lane in those builds.Not covered
The case "a server whose HTML routes were still being built is released with it" of the same file prints
kept 1on the same lane (builds 126485, 126781, 127229). That is another fixture and another wait.