fix: stop searches gracefully on Windows console Ctrl-C - #1386
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MilesCranmer merged 3 commits intoSep 27, 2026
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Co-authored-by: Miles Cranmer <miles.cranmer@gmail.com>
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A Ctrl-C arriving while the original SIGINT handler is installed raises KeyboardInterrupt, which could skip registering or removing the console handler and leave Windows holding a freed callback. The test now sends its interrupt once the fit has armed the search, instead of after a fixed delay. Co-authored-by: Miles Cranmer <miles.cranmer@gmail.com>
Co-authored-by: Miles Cranmer <miles.cranmer@gmail.com>
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Sep 27, 2026
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Pressing Ctrl-C in a Windows terminal during
model.fitkills the Python process. #1329 made interrupts stop the search gracefully from Jupyter on Windows, but a console Ctrl-C never reaches Python.Julia registers a console control handler at startup (
SetConsoleCtrlHandler(sigint_handler, 1)insrc/signals-win.c). Windows calls console handlers last-registered first, so Julia's runs before CPython's, returns TRUE, and exits the process with code 130. Python's SIGINT handler, and with it the stop byte thatExternalStoppolls for, never fires.For the duration of the search, PySR now registers its own console handler. Because it is registered last, it runs first. It passes
CTRL_C_EVENTto Python through_thread.interrupt_main(), the same route Jupyter's interrupt already takes, and it leaves other console events to the existing handlers. This does for Windows what thesigactionsave and restore already does for POSIX, sointerrupt.pyhas one if/else covering both platforms.TestSubprocessInterruptnow runs on Windows. The child process interrupts itself. On POSIX it sendsos.kill(os.getpid(), SIGINT). On Windows, where it is launched withCREATE_NEW_CONSOLE, it callsGenerateConsoleCtrlEvent(CTRL_C_EVENT, 0). The child runs a warm-up fit first so the interrupt lands on a running search, and it now requires non-empty partial results.Verification,
python -m pysr test interrupt:AssertionError: 130 != 0 : child failedRan 11 tests,OK (skipped=5); the subprocess test ran and passed, and the five skips are the POSIX-onlysigactionunit testsRan 11 tests,OK, no skipsRan 11 tests,OK