Ctrl+C in sloppy.py's terminal would hang the process when a worker of
the shared 4-thread I/O pool was mid-task in user code (e.g. a long-
running Gemini/Anthropic HTTP request). The hang chain:
1. SIGINT delivered to main thread
2. Python raises KeyboardInterrupt (default handler)
3. Exception propagates out of main()
4. Interpreter finalization begins
5. ThreadPoolExecutor.__del__ runs shutdown(wait=True)
6. shutdown(wait=True) joins all worker threads
7. The blocked worker never returns -> hang
An atexit-based fix (mirroring the conftest fix at 8957c9a5) was
attempted first: register pool.shutdown(wait=False) at pool creation.
Verified empirically that this DOES NOT WORK — atexit handlers do not
fire at all when a pool worker is blocked in user code. The hang still
occurs in ThreadPoolExecutor.__del__ -> shutdown(wait=True).
Production fix: a SIGINT handler installed by AppController.__init__
that drains the pool non-blockingly and calls os._exit(0), bypassing
the broken finalization chain. One wire covers all three modes
(GUI/headless/web) since they all create an AppController.
Files:
- src/app_controller.py: new module-level _install_sigint_exit_handler
helper called from __init__; one-line docstring at the function
level documents the rationale.
- tests/test_app_controller_sigint.py: new test file with 2 regression
tests (unit: handler is installed on main thread; subprocess: handler
exits within 2s when invoked with a blocked worker).
- tests/test_io_pool.py: module docstring updated to explain the
reverted atexit approach and point readers at the production fix.
Best-effort: signal.signal may fail on non-main threads (some conftest
warmup paths); failure is swallowed. The conftest's own atexit fix at
8957c9a5 covers the test fixture's normal-exit path.
Phase 2 Tasks T2.1-T2.4 of the startup_speedup_20260606 track.
NEW: src/io_pool.py
make_io_pool() factory: 4-worker ThreadPoolExecutor with
thread_name_prefix='controller-io'. The sanctioned way for any
background work. Replaces ad-hoc threading.Thread() calls per
the 'no new threads' rule.
NEW: src/warmup.py
WarmupManager: manages a list of modules to import on the shared
pool. Public API:
.submit(modules) - start warmup (call once)
.status() - {pending, completed, failed}
.is_done() - bool
.wait(timeout) - block until done
.on_complete(callback) - register completion callback
.reset() - clear state
Thread-safe (lock-guarded). 10 tests cover all paths.
NEW: tests/test_io_pool.py (4 tests):
- ThreadPoolExecutor returned
- 4 workers
- Threads named 'controller-io-*'
- Jobs run in parallel (barrier test)
NEW: tests/test_warmup.py (10 tests):
- One job per module submitted
- Initial pending list correct
- Failed imports tracked
- Done event set after all complete
- wait() blocks until done
- on_complete callback fires (and immediately if already done)
- Modules actually end up in sys.modules
- reset() clears state
- Jobs run concurrently (not serially)
All 14 tests pass. AppController integration is the next commit.
ed