Blocking queue.SimpleQueue.get() held in a native condition-variable wait could defer Python signal handlers until an item arrived or the timeout expired.

• Signal-responsive waits

  • Split semaphore waits into 100ms intervals, capped by the caller’s timeout deadline.
  • Run vm.check_signals() between intervals.

• Deadlock avoidance

  • Release the semaphore mutex before invoking signal handlers, allowing handlers to safely interact with the same queue.

• Regression coverage

  • Add a Unix signal snippet verifying SIGALRM is handled while SimpleQueue.get() remains blocked.

signal.setitimer(signal.ITIMER_REAL, 0.1)
threading.Thread(target=unblock_later).start()

q.get()  # signal handler runs before unblock_later() enqueues an item