# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# Copyright 2011 Justin Santa Barbara
# All Rights Reserved.
#
# Licensed 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.
"""Generic Node base class for all workers that run on hosts."""
import errno
import logging as std_logging
import os
import random
import signal
import sys
import time
import eventlet
from oslo.config import cfg
from heat.openstack.common import eventlet_backdoor
from heat.openstack.common.gettextutils import _
from heat.openstack.common import importutils
from heat.openstack.common import log as logging
from heat.openstack.common import threadgroup
rpc = importutils.try_import('heat.openstack.common.rpc')
CONF = cfg.CONF
LOG = logging.getLogger(__name__)
[docs]class Launcher(object):
"""Launch one or more services and wait for them to complete."""
def __init__(self):
"""Initialize the service launcher.
:returns: None
"""
self._services = threadgroup.ThreadGroup()
eventlet_backdoor.initialize_if_enabled()
@staticmethod
[docs] def run_service(service):
"""Start and wait for a service to finish.
:param service: service to run and wait for.
:returns: None
"""
service.start()
service.wait()
[docs] def launch_service(self, service):
"""Load and start the given service.
:param service: The service you would like to start.
:returns: None
"""
self._services.add_thread(self.run_service, service)
[docs] def stop(self):
"""Stop all services which are currently running.
:returns: None
"""
self._services.stop()
[docs] def wait(self):
"""Waits until all services have been stopped, and then returns.
:returns: None
"""
self._services.wait()
[docs]class SignalExit(SystemExit):
def __init__(self, signo, exccode=1):
super(SignalExit, self).__init__(exccode)
self.signo = signo
[docs]class ServiceLauncher(Launcher):
def _handle_signal(self, signo, frame):
# Allow the process to be killed again and die from natural causes
signal.signal(signal.SIGTERM, signal.SIG_DFL)
signal.signal(signal.SIGINT, signal.SIG_DFL)
raise SignalExit(signo)
[docs] def wait(self):
signal.signal(signal.SIGTERM, self._handle_signal)
signal.signal(signal.SIGINT, self._handle_signal)
LOG.debug(_('Full set of CONF:'))
CONF.log_opt_values(LOG, std_logging.DEBUG)
status = None
try:
super(ServiceLauncher, self).wait()
except SignalExit as exc:
signame = {signal.SIGTERM: 'SIGTERM',
signal.SIGINT: 'SIGINT'}[exc.signo]
LOG.info(_('Caught %s, exiting'), signame)
status = exc.code
except SystemExit as exc:
status = exc.code
finally:
if rpc:
rpc.cleanup()
self.stop()
return status
[docs]class ServiceWrapper(object):
def __init__(self, service, workers):
self.service = service
self.workers = workers
self.children = set()
self.forktimes = []
[docs]class ProcessLauncher(object):
def __init__(self):
self.children = {}
self.sigcaught = None
self.running = True
rfd, self.writepipe = os.pipe()
self.readpipe = eventlet.greenio.GreenPipe(rfd, 'r')
signal.signal(signal.SIGTERM, self._handle_signal)
signal.signal(signal.SIGINT, self._handle_signal)
def _handle_signal(self, signo, frame):
self.sigcaught = signo
self.running = False
# Allow the process to be killed again and die from natural causes
signal.signal(signal.SIGTERM, signal.SIG_DFL)
signal.signal(signal.SIGINT, signal.SIG_DFL)
def _pipe_watcher(self):
# This will block until the write end is closed when the parent
# dies unexpectedly
self.readpipe.read()
LOG.info(_('Parent process has died unexpectedly, exiting'))
sys.exit(1)
def _child_process(self, service):
# Setup child signal handlers differently
def _sigterm(*args):
signal.signal(signal.SIGTERM, signal.SIG_DFL)
raise SignalExit(signal.SIGTERM)
signal.signal(signal.SIGTERM, _sigterm)
# Block SIGINT and let the parent send us a SIGTERM
signal.signal(signal.SIGINT, signal.SIG_IGN)
# Reopen the eventlet hub to make sure we don't share an epoll
# fd with parent and/or siblings, which would be bad
eventlet.hubs.use_hub()
# Close write to ensure only parent has it open
os.close(self.writepipe)
# Create greenthread to watch for parent to close pipe
eventlet.spawn_n(self._pipe_watcher)
# Reseed random number generator
random.seed()
launcher = Launcher()
launcher.run_service(service)
def _start_child(self, wrap):
if len(wrap.forktimes) > wrap.workers:
# Limit ourselves to one process a second (over the period of
# number of workers * 1 second). This will allow workers to
# start up quickly but ensure we don't fork off children that
# die instantly too quickly.
if time.time() - wrap.forktimes[0] < wrap.workers:
LOG.info(_('Forking too fast, sleeping'))
time.sleep(1)
wrap.forktimes.pop(0)
wrap.forktimes.append(time.time())
pid = os.fork()
if pid == 0:
# NOTE(johannes): All exceptions are caught to ensure this
# doesn't fallback into the loop spawning children. It would
# be bad for a child to spawn more children.
status = 0
try:
self._child_process(wrap.service)
except SignalExit as exc:
signame = {signal.SIGTERM: 'SIGTERM',
signal.SIGINT: 'SIGINT'}[exc.signo]
LOG.info(_('Caught %s, exiting'), signame)
status = exc.code
except SystemExit as exc:
status = exc.code
except BaseException:
LOG.exception(_('Unhandled exception'))
status = 2
finally:
wrap.service.stop()
os._exit(status)
LOG.info(_('Started child %d'), pid)
wrap.children.add(pid)
self.children[pid] = wrap
return pid
[docs] def launch_service(self, service, workers=1):
wrap = ServiceWrapper(service, workers)
LOG.info(_('Starting %d workers'), wrap.workers)
while self.running and len(wrap.children) < wrap.workers:
self._start_child(wrap)
def _wait_child(self):
try:
# Don't block if no child processes have exited
pid, status = os.waitpid(0, os.WNOHANG)
if not pid:
return None
except OSError as exc:
if exc.errno not in (errno.EINTR, errno.ECHILD):
raise
return None
if os.WIFSIGNALED(status):
sig = os.WTERMSIG(status)
LOG.info(_('Child %(pid)d killed by signal %(sig)d'),
dict(pid=pid, sig=sig))
else:
code = os.WEXITSTATUS(status)
LOG.info(_('Child %(pid)s exited with status %(code)d'),
dict(pid=pid, code=code))
if pid not in self.children:
LOG.warning(_('pid %d not in child list'), pid)
return None
wrap = self.children.pop(pid)
wrap.children.remove(pid)
return wrap
[docs] def wait(self):
"""Loop waiting on children to die and respawning as necessary"""
LOG.debug(_('Full set of CONF:'))
CONF.log_opt_values(LOG, std_logging.DEBUG)
while self.running:
wrap = self._wait_child()
if not wrap:
# Yield to other threads if no children have exited
# Sleep for a short time to avoid excessive CPU usage
# (see bug #1095346)
eventlet.greenthread.sleep(.01)
continue
while self.running and len(wrap.children) < wrap.workers:
self._start_child(wrap)
if self.sigcaught:
signame = {signal.SIGTERM: 'SIGTERM',
signal.SIGINT: 'SIGINT'}[self.sigcaught]
LOG.info(_('Caught %s, stopping children'), signame)
for pid in self.children:
try:
os.kill(pid, signal.SIGTERM)
except OSError as exc:
if exc.errno != errno.ESRCH:
raise
# Wait for children to die
if self.children:
LOG.info(_('Waiting on %d children to exit'), len(self.children))
while self.children:
self._wait_child()
[docs]class Service(object):
"""Service object for binaries running on hosts."""
def __init__(self, threads=1000):
self.tg = threadgroup.ThreadGroup(threads)
[docs] def stop(self):
self.tg.stop()
[docs] def wait(self):
self.tg.wait()
[docs]def launch(service, workers=None):
if workers:
launcher = ProcessLauncher()
launcher.launch_service(service, workers=workers)
else:
launcher = ServiceLauncher()
launcher.launch_service(service)
return launcher