Kill all workers when main process exits in prefork model

celery/concurrency/prefork.py

@@ -8,6 +8,7 @@
 from billiard.common import REMAP_SIGTERM, TERM_SIGNAME
 from billiard.pool import CLOSE, RUN
 from billiard.pool import Pool as BlockingPool
+from billiard.util import set_pdeathsig
 
 from celery import platforms, signals
 from celery._state import _set_task_join_will_block, set_default_app
@@ -41,6 +42,9 @@ def process_initializer(app, hostname):
     Initialize the child pool process to ensure the correct
     app instance is used and things like logging works.
     """
+    # Each running worker gets SIGKILL by OS when main process exits.
+    if platforms.signals.supported('SIGKILL'):
+        set_pdeathsig(platforms.signals.signum('SIGKILL'))
     _set_task_join_will_block(True)
     platforms.signals.reset(*WORKER_SIGRESET)
     platforms.signals.ignore(*WORKER_SIGIGNORE)

t/unit/concurrency/test_prefork.py

@@ -1,9 +1,11 @@
 import errno
 import os
 import socket
+import signal
 from itertools import cycle
 from unittest.mock import Mock, patch
 
+from billiard.util import set_pdeathsig
 import pytest
 from case import mock
 
@@ -53,11 +55,18 @@ def get(self):
         return self.value
 
 
+@patch('celery.platforms.set_mp_process_title')
 class test_process_initializer:
 
+    @staticmethod
+    def Loader(*args, **kwargs):
+        loader = Mock(*args, **kwargs)
+        loader.conf = {}
+        loader.override_backends = {}
+        return loader
+
     @patch('celery.platforms.signals')
-    @patch('celery.platforms.set_mp_process_title')
-    def test_process_initializer(self, set_mp_process_title, _signals):
+    def test_process_initializer(self, _signals, set_mp_process_title):
         with mock.restore_logging():
             from celery import signals
             from celery._state import _tls
@@ -67,13 +76,7 @@ def test_process_initializer(self, set_mp_process_title, _signals):
             on_worker_process_init = Mock()
             signals.worker_process_init.connect(on_worker_process_init)
 
-            def Loader(*args, **kwargs):
-                loader = Mock(*args, **kwargs)
-                loader.conf = {}
-                loader.override_backends = {}
-                return loader
-
-            with self.Celery(loader=Loader) as app:
+            with self.Celery(loader=self.Loader) as app:
                 app.conf = AttributeDict(DEFAULTS)
                 process_initializer(app, 'awesome.worker.com')
                 _signals.ignore.assert_any_call(*WORKER_SIGIGNORE)
@@ -100,6 +103,22 @@ def Loader(*args, **kwargs):
                 finally:
                     os.environ.pop('CELERY_LOG_FILE', None)
 
+    @patch('celery.concurrency.prefork.set_pdeathsig', wraps=set_pdeathsig)
+    def test_pdeath_sig(self, _set_pdeathsig, set_mp_process_title):
+        with mock.restore_logging():
+            from celery import signals
+            on_worker_process_init = Mock()
+            signals.worker_process_init.connect(on_worker_process_init)
+            from celery.concurrency.prefork import process_initializer
+
+            with self.Celery(loader=self.Loader) as app:
+                app.conf = AttributeDict(DEFAULTS)
+                process_initializer(app, 'awesome.worker.com')
+            if hasattr(signal, 'SIGKILL'):
+                _set_pdeathsig.assert_called_once_with(signal.SIGKILL)
+            else:
+                _set_pdeathsig.assert_not_called()
+
 
 class test_process_destructor: