retoorandClaude Sonnet 5
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- Plexer: always-active terminal multiplexing. NativePlexerController/ TmuxPlexerController share one interface, chosen by which env var is already set (TAI_PLEXER_SOCKET vs TMUX_PANE); NativePlexerBackend is the pty.fork()-based wrapper (raw mode, SIGWINCH resize forwarding, a Unix-socket control protocol, continuous session logging, a Ctrl+A prefix key distinct from tmux's own Ctrl+B). Auto-wraps new interactive shells via a .bashrc hook mirroring the existing command-not-found install pattern, gated on $TMUX/$TAI_PLEXER_ACTIVE/ a $HOME/.tai-no-plexer bypass. New plexer_send/read/type/status tools, env-gated on a detected controller. - tests/container.py + docker-compose.yml + tests/docker/Dockerfile: a disposable podman/docker image for the tests that must never touch a real machine (installing the plexer hook into a real ~/.bashrc, a live tmux session). Required suite (test_seal.py, test_tai.py, tests/plexer.py, tests/bashrc.py) gates the result; tests/rag.py runs as best-effort since its real-LLM dependency can't be satisfied inside a disposable container with no nested engine. - tests/bashrc.py: real end-to-end hook install + bash -i auto-wrap, anti-recursion, tmux-active skip, non-interactive skip, a live TmuxPlexerController test, and an install/uninstall round-trip. - tests/plexer.py: NativePlexerBackend under a real pty, plus a dedicated robustness pass (file permissions, >64KB payload framing, a malformed control request, a genuine self-deadlock fix in the write-to-child path). - tai_test.py: the shared async process-driving framework (pipe/pty transport, group-wide kill-and-reap, a StdinBridge for --interactive) both test files build on. - ChatClient last-resort backend: when there's no local opencode CLI but the sandbox box is already running, install opencode into it (official Node tarball, not apt -- apt's nodejs/npm pull in webpack/babel/jest as transitive deps) and route through it instead of giving up. Only reachable after the first retry round already failed everything else; never creates the box itself. TmuxPlexerController.status() fixed to use `list-panes` instead of `display-message -p`, which silently fell back to the default pane instead of erroring against a dead target. - Fix 4 pre-existing test_tai.py bugs surfaced by running it in a clean environment for the first time: two stale mock signatures (subprocess.run's stdout= kwarg, Chat.complete's deadline= kwarg), one $TMUX-dependent catalog assertion, one tty-dependent color assertion. - research/: a sourced research archive (Source Dossier/Citation Card/Conclusion tiers) backing the above design decisions, with its own audit.py consistency checker. - .gitignore: fix a blanket *.md rule that was about to silently drop the entire research/ archive from version control; add __pycache__/ and the one-off debug transcript this session started from. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
48 lines
2.7 KiB
Markdown
48 lines
2.7 KiB
Markdown
# Understanding asyncio.subprocess.Process garbage collection — discuss.python.org
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## Metadata
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| Field | Value |
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| Institute | Molodetz Institute — Research & Retrieval Division |
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| Subject | async-pty-process-testing |
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| Document type | Source Dossier |
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| Tier | 1 |
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| Source title | Understanding asyncio.subprocess.Process garbage collection |
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| Source URL | https://discuss.python.org/t/understanding-asyncio-subprocess-process-garbage-collection/105973 |
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| Source publisher / author | Python Discourse community |
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| Source type | forum thread |
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| Source date (published) | Unknown — not stated |
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| Date researched | 2026-10-09 |
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| Researched by | tai (agent), model: Claude Sonnet 5, on behalf of retoor |
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| Research method | web search synthesis |
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| Confidence | Medium |
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| Status | Active |
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## Summary
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A Discourse thread examining what happens to a still-running `asyncio.subprocess.Process` object when it's garbage collected. The stdlib documentation states the child gets killed as a safety net in that case — but a forum participant reported observing output continuing to appear after the "owning" script had already finished, suggesting this safety net is not reliably instantaneous or complete in practice.
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## Key findings
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- `asyncio.subprocess.Process`'s own documentation states that if the process object is garbage collected while the process is still running, the child process will be killed — a documented safety net, not an accident of implementation.
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- Despite that documented behavior, a thread participant reported a case where a subprocess's "Step" output kept appearing after the main script had already exited, implying the GC-triggered kill either didn't fire promptly or didn't fully suppress output in that instance.
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## Pros / strengths
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- A concrete counter-example to "just let Python's GC clean it up" as a cleanup strategy — directly useful as evidence against relying on implicit cleanup.
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## Cons / limitations / caveats
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- A single forum report of unexpected behavior, not a reproduced, isolated bug report with a minimal test case — the exact conditions that produced it were not independently verified in this research pass.
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## Relevance to tai
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Reinforced the decision that `tai_test.py.TestCase.execute()` must explicitly call `await proc.terminate()` for every spawned process in its `finally` block, regardless of whether the test passed, failed, or was cancelled — never relying on Python's garbage collector or process-object destruction to clean anything up, consistent with the companion finding in `bpo-wait-for-timeout-leaves-process-alive.md` that a bare timeout alone doesn't guarantee cleanup either.
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## Changelog
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| Date | Change |
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| 2026-10-09 | Initial dossier created. |
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