Dettach duplicated signal handler from workers

python/seldon_core/app.py

@@ -1,12 +1,20 @@
 import os
 import logging
+import atexit
 
+from multiprocessing.util import _exit_function
 from typing import Dict, Union
 from gunicorn.app.base import BaseApplication
 
 logger = logging.getLogger(__name__)
 
 
+def post_worker_init(worker):
+    # Remove the atexit handler set up by the parent process
+    # https://github.com/benoitc/gunicorn/issues/1391#issuecomment-467010209
+    atexit.unregister(_exit_function)
+
+
 def accesslog(log_level: str) -> Union[str, None]:
     """
     Enable / disable access log in Gunicorn depending on the log level.

python/seldon_core/microservice.py

@@ -20,6 +20,7 @@
     UserModelApplication,
     accesslog,
     threads,
+    post_worker_init,
 )
 
 logger = logging.getLogger(__name__)
@@ -53,18 +54,23 @@ def start_servers(
        Auxilary flask process
 
     """
-    p2 = mp.Process(target=target2)
-    p2.daemon = True
-    p2.start()
+    p2 = None
+    if target2:
+        p2 = mp.Process(target=target2, daemon=True)
+        p2.start()
 
-    p3 = mp.Process(target=metrics_target)
-    p3.daemon = True
-    p3.start()
+    p3 = None
+    if metrics_target:
+        p3 = mp.Process(target=metrics_target, daemon=True)
+        p3.start()
 
     target1()
 
-    p2.join()
-    p3.join()
+    if p2:
+        p2.join()
+
+    if p3:
+        p3.join()
 
 
 def parse_parameters(parameters: Dict) -> Dict:
@@ -391,6 +397,7 @@ def rest_prediction_server():
                     "workers": args.workers,
                     "max_requests": args.max_requests,
                     "max_requests_jitter": args.max_requests_jitter,
+                    "post_worker_init": post_worker_init,
                 }
                 app = seldon_microservice.get_rest_microservice(
                     user_object, seldon_metrics
@@ -452,6 +459,7 @@ def rest_metrics_server():
                 "timeout": 5000,
                 "max_requests": args.max_requests,
                 "max_requests_jitter": args.max_requests_jitter,
+                "post_worker_init": post_worker_init,
             }
             StandaloneApplication(app, options=options).run()
 
@@ -465,7 +473,7 @@ def rest_metrics_server():
     else:
         server2_func = None
 
-        logger.info("Starting servers")
+    logger.info("Starting servers")
     start_servers(server1_func, server2_func, metrics_server_func)