Optimizations, closing db

src/plone.server/plone/server/factory/app.py

@@ -13,6 +13,7 @@
 from plone.server.interfaces import IApplication
 from plone.server.interfaces import IDatabaseConfigurationFactory
 from plone.server.interfaces.content import IContentNegotiation
+from plone.server.interfaces import IDatabase
 from plone.server.traversal import TraversalRouter
 from zope.component import getAllUtilitiesRegisteredFor
 from zope.component import getUtility
@@ -214,3 +215,6 @@ def make_app(config_file=None, settings=None):
 async def close_utilities(app):
     for utility in getAllUtilitiesRegisteredFor(IAsyncUtility):
         asyncio.ensure_future(utility.finalize(app=app), loop=app.loop)
+    for db in app.router._root:
+        if IDatabase.providedBy(db[1]):
+            db[1]._db.close()

src/plone.server/plone/server/factory/content.py

@@ -8,13 +8,14 @@
 from zope.component import getUtility
 from zope.component import provideUtility
 from zope.interface import implementer
+from concurrent.futures import ThreadPoolExecutor
 
 import asyncio
 
 
 @implementer(IApplication)
 class ApplicationRoot(object):
-
+    executor = ThreadPoolExecutor(max_workers=100)
     root_user = None
 
     def __init__(self, config_file):
@@ -27,7 +28,7 @@ def add_async_utility(self, config):
         factory = import_class(config['factory'])
         utility_object = factory(config['settings'])
         provideUtility(utility_object, interface)
-        task = asyncio.ensure_future(utility_object.initialize(app=self))
+        task = asyncio.ensure_future(utility_object.initialize(app=self.app))
         self.add_async_task(config['provides'], task, config)
 
     def add_async_task(self, ident, task, config):

src/plone.server/plone/server/json/serialize_content.py

@@ -117,7 +117,7 @@ def __call__(self):
         security = IInteraction(self.request)
         length = len(self.context)
 
-        if length > MAX_ALLOWED:
+        if length > MAX_ALLOWED or length == 0:
             result['items'] = []
         else:
             result['items'] = [

src/plone.server/plone/server/transactions.py

@@ -195,7 +195,6 @@ def savepoint(self):
 
 
 class RequestAwareConnection(ZODB.Connection.Connection):
-    executor = ThreadPoolExecutor(max_workers=100)
     lock = threading.Lock()
 
     def _getReadCurrent(self):