Encode the hard-won lesson from the forkserver
cancel-cascade investigation into two skill docs
so future sessions grep-find it before spelunking
into trio internals.
Deats,
- `.claude/skills/conc-anal/SKILL.md`:
- new "Unbounded waits in cleanup paths"
section — rule: bound every `await X.wait()`
in cleanup paths with `trio.move_on_after()`
unless the setter is unconditionally
reachable. Recent example:
`ipc_server.wait_for_no_more_peers()` in
`async_main`'s finally (was unbounded,
deadlocked when any peer handler stuck)
- new "The capture-pipe-fill hang pattern"
section — mechanism, grep-pointers to the
existing `conftest.py` guards (`tests/conftest
.py:258`, `:316`), cross-ref to the full
post-mortem doc, and the grep-note: "if a
multi-subproc tractor test hangs, `pytest -s`
first, conc-anal second"
- `.claude/skills/run-tests/SKILL.md`: new
"Section 9: The pytest-capture hang pattern
(CHECK THIS FIRST)" with symptom / cause /
pre-existing guards to grep / three-step debug
recipe (try `-s`, lower loglevel, redirect
stdout/stderr) / signature of this bug vs. a
real code hang / historical reference
Cost several investigation sessions before the
capture-pipe issue surfaced — it was masked by
deeper cascade deadlocks. Once the cascades were
fixed, the tree tore down enough to generate
pipe-filling log volume. Lesson: **grep this
pattern first when any multi-subproc tractor test
hangs under default pytest but passes with `-s`.**
(this commit msg was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code
The previous cleanup recipe went straight to
SIGTERM+SIGKILL, which hides bugs: tractor is
structured concurrent — `_trio_main` catches SIGINT
as an OS-cancel and cascades `Portal.cancel_actor`
over IPC to every descendant. So a graceful SIGINT
exercises the actual SC teardown path; if it hangs,
that's a real bug to file (the forkserver `:1616`
zombie was originally suspected to be one of these
but turned out to be a teardown gap in
`_ForkedProc.kill()` instead).
Deats,
- step 1: `pkill -INT` scoped to `$(pwd)/py*` — no
sleep yet, just send the signal
- step 2: bounded wait loop (10 × 0.3s = ~3s) using
`pgrep` to poll for exit. Loop breaks early on
clean exit
- step 3: `pkill -9` only if graceful timed out, w/
a logged escalation msg so it's obvious when SC
teardown didn't complete
- step 4: same SIGINT-first ladder for the rare
`:1616`-holding zombie that doesn't match the
cmdline pattern (find PID via `ss -tlnp`, then
`kill -INT NNNN; sleep 1; kill -9 NNNN`)
- steps 5-6: UDS-socket `rm -f` + re-verify
unchanged
Goal: surface real teardown bugs through the test-
cleanup workflow instead of papering over them with
`-9`.
(this patch was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code
Fork-based backends (esp. `subint_forkserver`) can
leak child actor processes on cancelled / SIGINT'd
test runs; the zombies keep the tractor default
registry (`127.0.0.1:1616` / `/tmp/registry@1616.sock`)
bound, so every subsequent session can't bind and
50+ unrelated tests fail with the same
`TooSlowError` / "address in use" signature. Document
the pre-flight + post-cancel check as a mandatory
step 4.
Deats,
- **primary signal**: `ss -tlnp | grep ':1616'` for a
bound TCP registry listener — the authoritative
check since :1616 is unique to our runtime
- `pgrep -af` scoped to `$(pwd)/py[0-9]*/bin/python.*
_actor_child_main|subint-forkserv` for leftover
actor/forkserver procs — scoped deliberately so we
don't false-flag legit long-running tractor-
embedding apps like `piker`
- `ls /tmp/registry@*.sock` for stale UDS sockets
- scoped cleanup recipe (SIGTERM + SIGKILL sweep
using the same `$(pwd)/py*` pattern, UDS `rm -f`,
re-verify) plus a fallback for when a zombie holds
:1616 but doesn't match the pattern: `ss -tlnp` →
kill by PID
- explicit false-positive warning calling out the
`piker` case (`~/repos/piker/py*/bin/python3 -m
tractor._child ...`) so a bare `pgrep` doesn't lead
to nuking unrelated apps
Goal: short-circuit the "spelunking into test code"
rabbit-hole when the real cause is just a leaked PID
from a prior session, without collateral damage to
other tractor-embedding projects on the same box.
(this patch was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code
Rework section 3 from a worktree-only check into a
structured 3-step flow: detect active venv, interpret
results (Case A: active, B: none, C: worktree), then
run import + collection checks.
Deats,
- Case B prompts via `AskUserQuestion` when no venv
is detected, offering `uv sync` or manual activate
- add `uv run` fallback section for envs where venv
activation isn't practical
- new allowed-tools: `uv run python`, `uv run pytest`,
`uv pip show`, `AskUserQuestion`
(this commit msg was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code
New "Inspect last failures" section reads the pytest
`lastfailed` cache JSON directly — instant, no
collection overhead, and filters to `tests/`-prefixed
entries to avoid stale junk paths.
Also,
- add `jq` tool permission for `.pytest_cache/` files
(this commit msg was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code
All tests are registrar-actor integration scenarios
sharing intertwined helpers + `enable_modules=[__name__]`
task fns, so keep as one mod but rename to reflect
content. Now lives alongside `test_multiaddr.py` in
the new `tests/discovery/` subpkg.
Also,
- update 5 refs in `/run-tests` SKILL.md to match
the new path
- add `discovery/` subdir to the test directory
layout tree
(this patch was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code
Expand `run-tests` skill `allowed-tools` to cover
the documented pre-flight workflow: `git rev-parse`
for worktree detection, `python --version`, and
`UV_PROJECT_ENVIRONMENT=py* uv sync` for venv
setup. Also dedup `gh api`/`gh pr` entries in
`settings.local.json` and widen `py313` → `py*`
so non-3.13 setups aren't blocked.
Review: PR #440 (copilot-pull-request-reviewer)
https://github.com/goodboy/tractor/pull/440
(this patch was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code
Gud Boi