diff options
Diffstat (limited to 'openstack/common/service.py')
| -rw-r--r-- | openstack/common/service.py | 190 |
1 files changed, 183 insertions, 7 deletions
diff --git a/openstack/common/service.py b/openstack/common/service.py index 5141ae4..b464aea 100644 --- a/openstack/common/service.py +++ b/openstack/common/service.py @@ -19,8 +19,12 @@ """Generic Node base class for all workers that run on hosts.""" +import errno +import os +import random import signal import sys +import time import eventlet import greenlet @@ -119,6 +123,170 @@ class ServiceLauncher(Launcher): return status +class ServiceWrapper(object): + def __init__(self, service, workers): + self.service = service + self.workers = workers + self.children = set() + self.forktimes = [] + + +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(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 + + 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: + pid, status = os.wait() + 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'), locals()) + else: + code = os.WEXITSTATUS(status) + LOG.info(_('Child %(pid)d exited with status %(code)d'), locals()) + + 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 + + def wait(self): + """Loop waiting on children to die and respawning as necessary""" + while self.running: + wrap = self._wait_child() + if not wrap: + 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() + + class Service(object): """Service object for binaries running on hosts. @@ -127,18 +295,26 @@ class Service(object): def __init__(self, host, manager, *args, **kwargs): self.host = host self.manager = manager + self.running = False def start(self): + self.running = True if self.manager: self.manager.init_host() def stop(self): - pass + self.running = False def wait(self): - pass - - -def launcher(service): - l = Launcher() - l.launch_service(service) + while self.running: + time.sleep(.1) + + +def launch(service, workers=None): + if workers: + launcher = ProcessLauncher() + launcher.launch_service(service, workers=workers) + else: + launcher = ServiceLauncher() + launcher.launch_service(service) + return launcher |