fix(process_registry): finished processes no longer hold FDs for the TTL window (salvage #75162) - #98930
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૮ >ﻌ< ა ci reviewran on 3080dad — test(process_registry): trim handle-release tests to invaria
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Heads-up: #68948 (open, CI green) also touches |
Finished sessions retained their subprocess.Popen pipe objects (and PTY masters) until the finished-process TTL (FINISHED_TTL_SECONDS, default 30 minutes) elapsed. Under heavy background churn — deployments, archivers, watchers — finished-but-unpruned sessions accumulated one open pipe FD each, exhausting the gateway process's file descriptor budget and surfacing as a 'file descriptor limit' error on new background spawns. The registry never rejects spawns (it prunes oldest-finished at MAX_PROCESSES), so the real defect was the retained-handle leak, not a registry-cap rejection. The fix closes each finished session's Popen stdout/stderr/stdin streams and PTY master in _move_to_finished(), right after the reader loop drains EOF. poll()/wait()/read_log() serve output from the buffered output_buffer — never from the pipe — so the release is lossless. Tests: 4 new cases in TestFinishedHandleRelease — Popen pipes closed, PTY closed, no-handle sessions safe, and poll() still serves buffered output after the release. All 4 fail on main (reproduction) and pass with the fix.
…llow-up) Widen #75162: _prune_if_needed() drops finished sessions (TTL expiry and oldest-finished eviction at MAX_PROCESSES) — release their Popen/PTY handles there too, covering sessions inserted into _finished without passing through _move_to_finished(). The release helper is idempotent, so double-close on the normal path is a no-op. Adds two tests: prune releases handles of dropped sessions, and a still-running session's pipe stays open.
…ath race _release_finished_handles read the dataclass fields through getattr fallbacks and swallowed every exception; use the real attributes, suppress only OSError/ValueError on the pipe close (an stdin flush can hit EPIPE), and rely on ptyprocess/pywinpty close() idempotence for the master fd. The call-site comment claimed the reader had always drained the pipe; on kill_process/_reconcile_local_exit the reader may still be reading, so state what actually happens (its next read raises, the loop exits).
…prune fixture Drop the no-op and still-running change-detectors (4 invariant tests remain: pipe closed on finish, PTY closed on finish, poll still serves buffered output, prune releases handles). The accretion-caps fake session now carries process/_pty like the real dataclass, since prune reads them.
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Summary
Finished background processes now release their OS handles (Popen pipes + PTY masters) immediately instead of holding them for the 30-minute finished-TTL window — heavy background churn can no longer exhaust the gateway's file-descriptor budget.
Salvage of #75162 by @RGerrish (commit cherry-picked, authorship preserved) onto current main, plus a follow-up widening commit. Zed shipped the same fix class this week (zed-industries/zed#62978 — completed agent terminals retained live PTY resources), which is what surfaced this stalled PR in the weekly scout.
Changes
tools/process_registry.py: idempotent_release_finished_handles()called from_move_to_finished()(contributor commit) and from both_prune_if_needed()drop paths — TTL expiry + oldest-finished eviction — which the original PR missed (follow-up commit).tests/tools/test_process_registry.py: contributor'sTestFinishedHandleRelease+ 2 new tests (prune releases handles; still-running session's pipe stays open).Validation
tests/tools/test_process_registry.pyscripts/audit_pr_attribution.py --fix— all emails mappedLive repro: contributor's failing-first test red on main (
proc.stdout.closedstays False after finish); green on branch; live E2E above confirms on real processes.Safety notes: send-input paths already guard on
session.exited(gracefulalready_exited), reader threads drain before_move_to_finishedruns so handles never close under a live reader, checkpoint-recovered detached sessions carry no local handles.Infographic