Revert "Ensure we are not exhausting the sqlalchemy pool"

This reverts commit 64bc862f6f.

Now that we don't monkey patch anymore with eventlet, we're sure the
situation fixed previously by that patch where a process could consume
more messages than having SQL connection can't happen anymore.

Change-Id: Ia0f1037e1b8c3e079d382c608e047614e388ce37

ceilometer/storage/impl_sqlalchemy.py

@@ -19,7 +19,6 @@
 
 from __future__ import absolute_import
 import datetime
-import eventlet
 import operator
 import os
 import types
@@ -28,7 +27,6 @@ from sqlalchemy import and_
 from sqlalchemy import desc
 from sqlalchemy import func
 from sqlalchemy.orm import aliased
-from sqlalchemy import pool
 
 from ceilometer.openstack.common.db import exception as dbexc
 import ceilometer.openstack.common.db.sqlalchemy.session as sqlalchemy_session
@@ -178,14 +176,6 @@ class Connection(base.Connection):
             conf.database.connection = \
                 os.environ.get('CEILOMETER_TEST_SQL_URL', url)
 
-        session = sqlalchemy_session.get_session()
-        engine = session.get_bind()
-        if isinstance(engine.pool, pool.QueuePool):
-            poolsize = engine.pool.size() + engine.pool._max_overflow
-            self.pool = eventlet.GreenPool(poolsize)
-        else:
-            self.pool = None
-
     def upgrade(self):
         session = sqlalchemy_session.get_session()
         migration.db_sync(session.get_bind())
@@ -231,17 +221,8 @@ class Connection(base.Connection):
             setattr(obj, k, kwargs[k])
         return obj
 
-    def record_metering_data(self, data):
-        if self.pool:
-            if self.pool.waiting() > 0:
-                LOG.warn(_("Sqlalchemy connection pool is full, "
-                           "perhaps pool_size should be increased"))
-            self.pool.spawn(self._real_record_metering_data, data)
-        else:
-            self._real_record_metering_data(data)
-
     @classmethod
-    def _real_record_metering_data(cls, data):
+    def record_metering_data(cls, data):
         """Write the data to the backend storage system.
 
         :param data: a dictionary such as returned by