refactor(fasthttp): make both Linux (epoll) and BSD (kqueue) backends asynchronous by guweigang · Pull Request #27477 · vlang/v

guweigang · 2026-06-17T07:39:31Z

Summary

This PR refactors both the Linux (epoll) and BSD (kqueue) backends of the fasthttp module to be fully asynchronous using the LoopCommand channel pattern and spawn coroutines.

It resolves the upstream review comments regarding the BSD kqueue async PR (#27477) by:

P1 (Linux block/hang on loopback request): The Linux backend previously processed requests synchronously inline within the main epoll event loop thread, blocking the loop and causing timeouts for nested loopback requests (e.g. test_handler_can_make_loopback_request_to_same_server). We refactored vlib/fasthttp/fasthttp_linux.v to decouple request handling into async coroutines, allowing loopback requests to process without blocking.
P2 (Connection lifetime race under .manual takeover): For .manual takeover mode, we deferred the server.end_request() call in both backends until the event loop has successfully deregistered the fd and cleaned tracking maps, avoiding early socket closures during server shutdown.
Keep-alive epoll re-registration: Fixed a bug where keep-alive connections could lose epoll registration after their first request if the write completed instantly (i.e. epollout_was_armed was false). The socket is now unconditionally re-added to the epoll listen mask on keep-alive completion.

Key Changes

vlib/fasthttp/fasthttp_linux.v:
- Added LoopCommandKind and LoopCommand structs.
- Decoupled request processing into process_request_async.
- Implemented drain_loop_commands to safely process commands and update connection/write maps in the main thread.
- Unconditionally re-registers sockets to epoll for keep-alive connections on write completion.
vlib/fasthttp/fasthttp_bsd.c.v:
- Deferred server.end_request() under .manual_takeover to the loop command handler.
vlib/fasthttp/fasthttp_test.v:
- Re-enabled the loopback nested request test for Linux ($if linux || bsd).

Verification

Tested locally on macOS (BSD kqueue backend): 2 passed, 2 total.
Tested in a Linux (Debian aarch64) container (Linux epoll backend): 2 passed, 2 total (including nested loopback test).

chatgpt-codex-connector · 2026-06-17T07:47:33Z

Codex usage limits have been reached for code reviews. Please check with the admins of this repo to increase the limits by adding credits.

guweigang · 2026-06-18T04:02:22Z

@codex review

chatgpt-codex-connector · 2026-06-18T04:02:30Z

You have reached your Codex usage limits for code reviews. You can see your limits in the Codex usage dashboard.

JalonSolov · 2026-06-18T18:24:15Z

@codex review

chatgpt-codex-connector

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: b48a62cf56

ℹ️ About Codex in GitHub

Codex has been enabled to automatically review pull requests in this repo. Reviews are triggered when you

Open a pull request for review
Mark a draft as ready
Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

When you sign up for Codex through ChatGPT, Codex can also answer questions or update the PR, like "@codex address that feedback".

…race

medvednikov · 2026-06-19T20:32:00Z

@codex review

chatgpt-codex-connector

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 68402cd3b2

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

Open a pull request for review
Mark a draft as ready
Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

JalonSolov · 2026-06-21T00:54:27Z

@codex review

chatgpt-codex-connector

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 5de24dda04

ℹ️ About Codex in GitHub

Codex has been enabled to automatically review pull requests in this repo. Reviews are triggered when you

Open a pull request for review
Mark a draft as ready
Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

When you sign up for Codex through ChatGPT, Codex can also answer questions or update the PR, like "@codex address that feedback".

guweigang · 2026-06-21T11:21:54Z

Addressed the latest review findings:

allocate Linux async write state independently from the spawned thread's prealloc scope
complete BSD reusable-request accounting on the event-loop thread, avoiding the shutdown race
wake epoll/kqueue immediately after workers enqueue loop commands
add Linux and BSD regression coverage for lifecycle ownership and poll wakeups

Validation:

macOS: fasthttp module suite: 3 passed, 1 Linux-only test skipped
macOS prealloc fasthttp test: passed
Ubuntu ARM64 with VFLAGS='-gc none -cc gcc': fasthttp module suite: 3 passed, 1 BSD-only test skipped
Ubuntu ARM64 prealloc regression set: 2/2 passed

JalonSolov · 2026-06-21T12:20:29Z

@codex review

chatgpt-codex-connector · 2026-06-21T12:26:55Z

Codex Review: Didn't find any major issues. What shall we delve into next?

Reviewed commit: b7a287ce4e

ℹ️ About Codex in GitHub

Codex has been enabled to automatically review pull requests in this repo. Reviews are triggered when you

Open a pull request for review
Mark a draft as ready
Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

When you sign up for Codex through ChatGPT, Codex can also answer questions or update the PR, like "@codex address that feedback".

JalonSolov · 2026-06-21T14:35:31Z

linux fasthttp regression test is failing...

https://github.com/vlang/v/actions/runs/27902688632/job/82565746225?pr=27477#step:14:36

guweigang · 2026-06-21T14:41:41Z

linux fasthttp regression test is failing...

https://github.com/vlang/v/actions/runs/27902688632/job/82565746225?pr=27477#step:14:36

Got that， I will fix this

guweigang · 2026-06-22T10:54:42Z

Addressed the remaining Linux CI failures:

split the Linux prealloc regression from the regular regression suite; the prealloc-only test now uses linux && !tinyc, since TCC does not implement _Thread_local
keep the fasthttp veb user context in the request heap/arena so manual-takeover work can safely outlive the async request worker
remove the duplicate EPOLL_CTL_DEL during manual takeover
add a focused regression proving the prealloc write state remains valid after its worker exits

Root cause of the musl SSE crash: the SSE child thread received a pointer to a user context stored on the async parent worker's stack. With -gc none/musl, the parent exited first and the child dereferenced the retired stack. GDB reproduced the crash in veb.sse.start_connection; the heap/arena-backed context fixes that ownership violation.

Validation:

macOS SSE test: passed
macOS fasthttp module: 3 passed, 2 Linux-only tests skipped
Ubuntu ARM64 GCC with -gc none: regular, prealloc, and existing fasthttp tests passed
Ubuntu ARM64 musl-gcc with -gc none: SSE passed (previously deterministic SIGSEGV/code 139)
Ubuntu ARM64 TCC: regular Linux regression passed; prealloc regression correctly skipped

JalonSolov · 2026-06-22T11:47:19Z

@codex review

chatgpt-codex-connector

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: a3f5a1e5e5

ℹ️ About Codex in GitHub

Codex has been enabled to automatically review pull requests in this repo. Reviews are triggered when you

Open a pull request for review
Mark a draft as ready
Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

When you sign up for Codex through ChatGPT, Codex can also answer questions or update the PR, like "@codex address that feedback".

guweigang · 2026-06-23T06:56:05Z

Updated for the latest P2 review.

Changes:

BSD /kqueue manual takeover cleanup now verifies clients[fd] still points at the stale command's Conn before deleting the map entry and kqueue events. This avoids deleting events for a newly accepted connection that reused the same fd after user code closed the takeover socket.
added a BSD regression test covering the reused-fd stale manual_takeover command case.
merged latest upstream/master into the PR branch.

Validation:

macOS: ./v -g -keepc -o ./vnew cmd/v
macOS: ./vnew test vlib/fasthttp/fasthttp_bsd_regression_test.c.v -> 1 passed
Linux Orb Ubuntu with VFLAGS='-gc none -cc gcc': ./v -g -keepc -o ./vnew cmd/v
Linux Orb Ubuntu: ./vnew test vlib/fasthttp/fasthttp_linux_regression_test.v vlib/fasthttp/fasthttp_linux_prealloc_regression_test.v vlib/fasthttp/fasthttp_test.v -> 3 passed

JalonSolov · 2026-06-23T12:04:32Z

@codex review

chatgpt-codex-connector

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: dd86d21b27

ℹ️ About Codex in GitHub

Codex has been enabled to automatically review pull requests in this repo. Reviews are triggered when you

Open a pull request for review
Mark a draft as ready
Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

When you sign up for Codex through ChatGPT, Codex can also answer questions or update the PR, like "@codex address that feedback".

guweigang · 2026-06-24T13:12:43Z

Updated for the latest P2 review.

Changes:

Linux fasthttp now tags accepted client fds with a per-connection generation.
async loop commands carry that generation, and manual_takeover cleanup only deletes fd-keyed client state when the queued command still matches the currently tracked connection.
added Linux regression coverage for a stale manual_takeover command arriving after the same fd has been reused, preserving the new connection's buffer/read-start/closing state.
merged latest upstream/master into the branch before pushing.

Validation:

macOS: ./v -g -keepc -o ./vnew cmd/v
macOS: ./vnew test vlib/fasthttp/fasthttp_bsd_regression_test.c.v vlib/fasthttp/fasthttp_linux_regression_test.v -> 1 passed, 1 skipped (Linux-only)
Linux Orb Ubuntu with VFLAGS='-gc none -cc gcc': ./v -g -keepc -o ./vnew cmd/v
Linux Orb Ubuntu: ./vnew test vlib/fasthttp/fasthttp_linux_regression_test.v vlib/fasthttp/fasthttp_linux_prealloc_regression_test.v vlib/fasthttp/fasthttp_test.v -> 3 passed

JalonSolov · 2026-06-24T13:57:58Z

@codex review

chatgpt-codex-connector · 2026-06-24T13:58:09Z

Codex usage limits have been reached for code reviews. Please check with the admins of this repo to increase the limits by adding credits.

fix: improve fasthttp bsd processing using loop command channel

b48a62c

guweigang marked this pull request as ready for review June 17, 2026 07:47

chatgpt-codex-connector Bot reviewed Jun 18, 2026

View reviewed changes

Comment thread vlib/fasthttp/fasthttp_test.v

Comment thread vlib/fasthttp/fasthttp_bsd.c.v Outdated

guweigang added 2 commits June 19, 2026 09:10

fix(fasthttp): fix manual takeover shutdown race and guard test to BSD

c7222f8

refactor(fasthttp): make linux backend asynchronous and fix loopback …

68402cd

…race

guweigang changed the title ~~fasthttp: process BSD requests outside the kqueue loop~~ refactor(fasthttp): make both Linux (epoll) and BSD (kqueue) backends asynchronous Jun 19, 2026

chatgpt-codex-connector Bot reviewed Jun 19, 2026

View reviewed changes

Comment thread vlib/fasthttp/fasthttp_linux.v

Comment thread vlib/fasthttp/fasthttp_linux.v Outdated

guweigang added 2 commits June 20, 2026 10:58

fix(fasthttp): close Linux async request races

7845d39

test(fasthttp): cover Linux async request lifecycle

5de24dd

chatgpt-codex-connector Bot reviewed Jun 21, 2026

View reviewed changes

Comment thread vlib/fasthttp/fasthttp_linux.v Outdated

guweigang added 2 commits June 21, 2026 14:50

fix(fasthttp): close async poll lifecycle races

ef66e1b

test(fasthttp): silence epoll union warning

b7a287c

guweigang added 3 commits June 22, 2026 14:47

fix(fasthttp): support takeover with musl and tcc CI

5ec4483

test(fasthttp): clean prealloc regression imports

1d6739d

test(fasthttp): wait for prealloc worker exit

a3f5a1e

chatgpt-codex-connector Bot reviewed Jun 22, 2026

View reviewed changes

Comment thread vlib/fasthttp/fasthttp_bsd.c.v Outdated

fix(fasthttp): guard stale takeover fd cleanup

5b68dea

Merge remote-tracking branch 'upstream/master' into fix-fasthttp-bsd

dd86d21

chatgpt-codex-connector Bot reviewed Jun 23, 2026

View reviewed changes

Comment thread vlib/fasthttp/fasthttp_linux.v Outdated

guweigang added 2 commits June 24, 2026 20:33

fix(fasthttp): guard stale Linux takeover cleanup

f609523

Merge remote-tracking branch 'upstream/master' into fix-fasthttp-bsd

02a18d4

Uh oh!

Uh oh!

Conversation

guweigang commented Jun 17, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Summary

Key Changes

Verification

Uh oh!

chatgpt-codex-connector Bot commented Jun 17, 2026

Uh oh!

guweigang commented Jun 18, 2026

Uh oh!

chatgpt-codex-connector Bot commented Jun 18, 2026

Uh oh!

JalonSolov commented Jun 18, 2026

Uh oh!

chatgpt-codex-connector Bot left a comment

Choose a reason for hiding this comment

💡 Codex Review

Uh oh!

Uh oh!

Uh oh!

medvednikov commented Jun 19, 2026

Uh oh!

chatgpt-codex-connector Bot left a comment

Choose a reason for hiding this comment

💡 Codex Review

Uh oh!

Uh oh!

Uh oh!

JalonSolov commented Jun 21, 2026

Uh oh!

chatgpt-codex-connector Bot left a comment

Choose a reason for hiding this comment

💡 Codex Review

Uh oh!

Uh oh!

guweigang commented Jun 21, 2026

Uh oh!

JalonSolov commented Jun 21, 2026

Uh oh!

chatgpt-codex-connector Bot commented Jun 21, 2026

Uh oh!

JalonSolov commented Jun 21, 2026

Uh oh!

guweigang commented Jun 21, 2026

Uh oh!

guweigang commented Jun 22, 2026

Uh oh!

JalonSolov commented Jun 22, 2026

Uh oh!

chatgpt-codex-connector Bot left a comment

Choose a reason for hiding this comment

💡 Codex Review

Uh oh!

Uh oh!

guweigang commented Jun 23, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

JalonSolov commented Jun 23, 2026

Uh oh!

chatgpt-codex-connector Bot left a comment

Choose a reason for hiding this comment

💡 Codex Review

Uh oh!

Uh oh!

guweigang commented Jun 24, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

JalonSolov commented Jun 24, 2026

Uh oh!

chatgpt-codex-connector Bot commented Jun 24, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

guweigang commented Jun 17, 2026 •

edited

Loading

guweigang commented Jun 23, 2026 •

edited

Loading

guweigang commented Jun 24, 2026 •

edited

Loading