Refactor periodic tasks.
This review allows periodic tasks to be enabled or disabled in the decorator, as well as by specifying an interval which is negative. The spacing between runs of a periodic task is now specified in seconds, with zero meaning the default spacing which is currently 60 seconds. There is also a new argument to the decorator which indicates if a periodic task _needs_ to be run in the nova-compute process. There is also a flag (run_external_periodic_tasks) which can be used to move these periodic tasks out of the nova-compute process. I also remove the periodic_interval flag to services, as the interval between runs is now dynamic based on the number of seconds that a periodic task wants to wait for its next run. For callers who want to twiddle the sleep period (for example unit tests), there is a create() argument periodic_interval_max which lets the period periodic_tasks() specifies be overridden. This is not exposed as a flag because I cannot see a use case for that. It is needed for unit testing however. DocImpact. Resolves bug 939087. Change-Id: I7f245a88b8d229a481c1b65a4c0f1e2769bf3901
This commit is contained in:
Michael Still
@@ -54,8 +54,10 @@ This module provides Manager, a base class for managers.
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"""
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import eventlet
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import time
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from nova.db import base
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from nova import exception
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from nova.openstack.common import cfg
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from nova.openstack.common import log as logging
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from nova.openstack.common.plugin import pluginmanager
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@@ -63,25 +65,50 @@ from nova.openstack.common.rpc import dispatcher as rpc_dispatcher
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from nova.scheduler import rpcapi as scheduler_rpcapi
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from nova import version
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periodic_opts = [
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cfg.BoolOpt('run_external_periodic_tasks',
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default=True,
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help=('Some periodic tasks can be run in a separate process. '
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'Should we run them here?')),
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]
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CONF = cfg.CONF
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CONF.register_opts(periodic_opts)
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CONF.import_opt('host', 'nova.config')
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LOG = logging.getLogger(__name__)
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DEFAULT_INTERVAL = 60.0
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def periodic_task(*args, **kwargs):
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"""Decorator to indicate that a method is a periodic task.
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This decorator can be used in two ways:
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1. Without arguments '@periodic_task', this will be run on every tick
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1. Without arguments '@periodic_task', this will be run on every cycle
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of the periodic scheduler.
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2. With arguments, @periodic_task(ticks_between_runs=N), this will be
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run on every N ticks of the periodic scheduler.
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2. With arguments, @periodic_task(periodic_spacing=N), this will be
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run on approximately every N seconds. If this number is negative the
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periodic task will be disabled.
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"""
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def decorator(f):
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# Test for old style invocation
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if 'ticks_between_runs' in kwargs:
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raise exception.InvalidPeriodicTaskArg(arg='ticks_between_runs')
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# Control if run at all
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f._periodic_task = True
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f._ticks_between_runs = kwargs.pop('ticks_between_runs', 0)
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f._periodic_external_ok = kwargs.pop('external_process_ok', False)
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if f._periodic_external_ok and not CONF.run_external_periodic_tasks:
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f._periodic_enabled = False
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else:
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f._periodic_enabled = kwargs.pop('enabled', True)
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# Control frequency
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f._periodic_spacing = kwargs.pop('spacing', 0)
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f._periodic_last_run = time.time()
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return f
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# NOTE(sirp): The `if` is necessary to allow the decorator to be used with
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@@ -117,17 +144,39 @@ class ManagerMeta(type):
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cls._periodic_tasks = []
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try:
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cls._ticks_to_skip = cls._ticks_to_skip.copy()
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cls._periodic_last_run = cls._periodic_last_run.copy()
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except AttributeError:
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cls._ticks_to_skip = {}
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cls._periodic_last_run = {}
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try:
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cls._periodic_spacing = cls._periodic_spacing.copy()
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except AttributeError:
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cls._periodic_spacing = {}
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for value in cls.__dict__.values():
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if getattr(value, '_periodic_task', False):
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task = value
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name = task.__name__
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if task._ticks_between_runs >= 0:
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cls._periodic_tasks.append((name, task))
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cls._ticks_to_skip[name] = task._ticks_between_runs
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if task._periodic_spacing < 0:
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LOG.info(_('Skipping periodic task %(task)s because '
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'its interval is negative'),
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{'task': name})
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continue
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if not task._periodic_enabled:
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LOG.info(_('Skipping periodic task %(task)s because '
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'it is disabled'),
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{'task': name})
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continue
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# A periodic spacing of zero indicates that this task should
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# be run every pass
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if task._periodic_spacing == 0:
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task._periodic_spacing = None
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cls._periodic_tasks.append((name, task))
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cls._periodic_spacing[name] = task._periodic_spacing
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cls._periodic_last_run[name] = task._periodic_last_run
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class Manager(base.Base):
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@@ -158,30 +207,39 @@ class Manager(base.Base):
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def periodic_tasks(self, context, raise_on_error=False):
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"""Tasks to be run at a periodic interval."""
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idle_for = DEFAULT_INTERVAL
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for task_name, task in self._periodic_tasks:
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full_task_name = '.'.join([self.__class__.__name__, task_name])
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ticks_to_skip = self._ticks_to_skip[task_name]
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if ticks_to_skip > 0:
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LOG.debug(_("Skipping %(full_task_name)s, %(ticks_to_skip)s"
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" ticks left until next run"), locals())
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self._ticks_to_skip[task_name] -= 1
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continue
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# If a periodic task is _nearly_ due, then we'll run it early
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if self._periodic_spacing[task_name] is None:
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wait = 0
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else:
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wait = time.time() - (self._periodic_last_run[task_name] +
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self._periodic_spacing[task_name])
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if wait > 0.2:
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if wait < idle_for:
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idle_for = wait
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continue
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self._ticks_to_skip[task_name] = task._ticks_between_runs
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LOG.debug(_("Running periodic task %(full_task_name)s"), locals())
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self._periodic_last_run[task_name] = time.time()
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try:
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task(self, context)
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# NOTE(tiantian): After finished a task, allow manager to
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# do other work (report_state, processing AMPQ request etc.)
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eventlet.sleep(0)
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except Exception as e:
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if raise_on_error:
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raise
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LOG.exception(_("Error during %(full_task_name)s: %(e)s"),
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locals())
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if (not self._periodic_spacing[task_name] is None and
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self._periodic_spacing[task_name] < idle_for):
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idle_for = self._periodic_spacing[task_name]
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eventlet.sleep(0)
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return idle_for
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def init_host(self):
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"""Hook to do additional manager initialization when one requests
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the service be started. This is called before any service record
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