Add a custom gunicorn sync worker implementation which works around some issues

st2common/st2common/util/gunicorn_workers.py

@@ -0,0 +1,48 @@
+# Licensed to the StackStorm, Inc ('StackStorm') under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import sys
+
+from gunicorn.workers.sync import SyncWorker
+
+__all__ = [
+    'EventletSyncWorker'
+]
+
+
+class EventletSyncWorker(SyncWorker):
+    """
+    Custom sync worker for gunicorn which works with eventlet monkey patching.
+
+    This worker class fixes "AssertionError: do not call blocking functions from
+    the mainloop" and some other issues on SIGINT / SIGTERM signal.
+
+    The actual issue happens in "time.sleep" call in "handle_quit" method -
+    https://github.com/benoitc/gunicorn/blob/master/gunicorn/workers/base.py#L166
+    which results in the assertion failure here -
+    https://github.com/simplegeo/eventlet/blob/master/eventlet/greenthread.py#L27
+    """
+
+    def handle_quit(self, sig, frame):
+        try:
+            return super(EventletSyncWorker, self).handle_quit(sig=sig, frame=frame)
+        except AssertionError as e:
+            msg = str(e)
+
+            if 'do not call blocking functions from the mainloop' in msg:
+                # Workaround for "do not call blocking functions from the mainloop" issue
+                sys.exit(0)
+
+            raise e