fix: Don't handle CTRL_C_EVENT, call previous signal handler

neps/runtime.py

@@ -9,7 +9,7 @@
 import signal
 import time
 from contextlib import contextmanager
-from dataclasses import dataclass
+from dataclasses import dataclass, field
 from pathlib import Path
 from typing import (
     TYPE_CHECKING,
@@ -51,7 +51,6 @@ def _default_worker_name() -> str:
 SIGNALS_TO_HANDLE_IF_AVAILABLE = [
     "SIGINT",
     "SIGTERM",
-    "CTRL_C_EVENT",
 ]
 
 
@@ -155,7 +154,7 @@ class DefaultWorker(Generic[Loc]):
     worker_cumulative_evaluation_time_seconds: float = 0.0
     """The time spent evaluating configurations by this worker."""
 
-    _SIGNAL_HANDLER_FIRED: bool = False
+    _PREVIOUS_SIGNAL_HANDLERS: dict[int, signal._HANDLER] = field(default_factory=dict)
 
     @classmethod
     def new(
@@ -356,7 +355,8 @@ def _set_signal_handlers(self) -> None:
                 # HACK: Despite what python documentation says, the existance of a signal
                 # is not enough to guarantee that it can be caught.
                 with contextlib.suppress(ValueError):
-                    signal.signal(sig, self._emergency_cleanup)
+                    previous_signal_handler = signal.signal(sig, self._emergency_cleanup)
+                    self._PREVIOUS_SIGNAL_HANDLERS[sig] = previous_signal_handler
 
     def run(self) -> None:  # noqa: C901, PLR0915
         """Run the worker.
@@ -446,9 +446,8 @@ def run(self) -> None:  # noqa: C901, PLR0915
                         default_report_values=self.settings.default_report_values,
                     )
             except KeyboardInterrupt as e:
-                if not self._SIGNAL_HANDLER_FIRED:
-                    # This throws and we have stopped the worker at this point
-                    self._emergency_cleanup(signum=signal.SIGINT, frame=None, rethrow=e)
+                # This throws and we have stopped the worker at this point
+                self._emergency_cleanup(signum=signal.SIGINT, frame=None, rethrow=e)
 
             evaluation_duration = evaluated_trial.metadata.evaluation_duration
             assert evaluation_duration is not None
@@ -491,12 +490,10 @@ def run(self) -> None:  # noqa: C901, PLR0915
     def _emergency_cleanup(
         self,
         signum: int,
-        frame: Any,  # noqa: ARG002
+        frame: Any,
         rethrow: KeyboardInterrupt | None = None,
     ) -> None:
         """Handle signals."""
-        self._SIGNAL_HANDLER_FIRED = True
-
         global _CURRENTLY_RUNNING_TRIAL_IN_PROCESS  # noqa: PLW0603
         logger.error(
             f"Worker '{self.worker_id}' received signal {signum}. Stopping worker now!"
@@ -516,6 +513,9 @@ def _emergency_cleanup(
             finally:
                 _CURRENTLY_RUNNING_TRIAL_IN_PROCESS = None
 
+        previous_handler = self._PREVIOUS_SIGNAL_HANDLERS.get(signum)
+        if previous_handler is not None and callable(previous_handler):
+            previous_handler(signum, frame)
         if rethrow is not None:
             raise rethrow
         raise KeyboardInterrupt(f"Worker was interrupted by signal {signum}.")