Merge "Shuffle agents to send request"

ceilometer/agent/base.py

@@ -21,6 +21,7 @@
 import collections
 import fnmatch
 import itertools
+import random
 
 from oslo_config import cfg
 from oslo_context import context
@@ -37,6 +38,16 @@ from ceilometer import utils
 
 LOG = log.getLogger(__name__)
 
+OPTS = [
+    cfg.IntOpt('shuffle_time_before_polling_task',
+               default=0,
+               help='To reduce large requests at same time to Nova or other '
+                    'components from different compute agents, shuffle '
+                    'start time of polling task.'),
+]
+
+cfg.CONF.register_opts(OPTS)
+
 
 class PollsterListForbidden(Exception):
     def __init__(self):
@@ -237,10 +248,16 @@ class AgentManager(os_service.Service):
         # allow time for coordination if necessary
         delay_start = self.partition_coordinator.is_active()
 
+        # set shuffle time before polling task if necessary
+        delay_polling_time = random.randint(
+            0, cfg.CONF.shuffle_time_before_polling_task)
+
         for interval, task in six.iteritems(self.setup_polling_tasks()):
+            delay_time = (interval + delay_polling_time if delay_start
+                          else delay_polling_time)
             self.tg.add_timer(interval,
                               self.interval_task,
-                              initial_delay=interval if delay_start else None,
+                              initial_delay=delay_time,
                               task=task)
         self.tg.add_timer(cfg.CONF.coordination.heartbeat,
                           self.partition_coordinator.heartbeat)

ceilometer/opts.py

@@ -66,7 +66,8 @@ import ceilometer.volume.notifications
 def list_opts():
     return [
         ('DEFAULT',
-         itertools.chain(ceilometer.api.app.OPTS,
+         itertools.chain(ceilometer.agent.base.OPTS,
+                         ceilometer.api.app.OPTS,
                          ceilometer.cmd.polling.CLI_OPTS,
                          ceilometer.compute.notifications.OPTS,
                          ceilometer.compute.util.OPTS,

doc/source/architecture.rst

@@ -382,6 +382,12 @@ the publishers defined in the pipeline configuration. For example,
 the ``notifier`` publisher converts the Sample to metering messages, which it
 then signs and transmits on the metering message bus.
 
+Please notice that there's an optional config called
+``shuffle_time_before_polling_task`` in ceilometer.conf. Enable this by
+setting an integer greater than zero to shuffle agents to start polling task,
+so that fluff up the time of sending requests to nova or other components to
+avoid large number of requests in short time.
+
 The frequency of polling is controlled via the pipeline configuration.
 See :ref:`Pipeline-Configuration` for details.