python使用eventlet(协程)启动多个daemon process(守护进程)
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这里我们需要解决的问题是:我们有多个服务,且每个服务(server)都是守护进程(daemon process),我们希望一次启动我们所有的服务,即使用eventlet创建我们的daemon processes
1.首先创建我们的守护进程
先创建我们的守护进程类,通过fork()函数实现.
* 关于我们为啥要使用signal.signal(signal.SIGCHLD,signal.SIG_IGN),请参考:
http://blog.csdn.net/u010571844/article/details/50419798.
* 第一次fork()后父进程使用的是sys.exit(0),会产生SystemExit的异常,我们不希望父进程退出,因为我们还希望使用父进程创建其他守护进程,我们可以catch Systemxit 这个异常。
* 第二次fork()后我们使用的是os._exit(0),父进程直接退出。这里为了避免父进程产生僵尸进程,使用了signal.signal(signal.SIGCHLD,signal.SIG_IGN)函数,使父进程的父进程不在关心他的子进程,子进程结束,由系统内核回收。僵尸进程参考:http://blog.csdn.net/u010571844/article/details/50419518
* sys.exit(0)与os._exit(0) 参考:http://blog.csdn.net/u010571844/article/details/50419261
# daemon.pyimport sysimport timeimport osimport atexitimport signalimport logginglog = logging.getLogger(__name__)class Daemon: """ A generic daemon class. Usage: subclass the Daemon class and override the run() method """ startmsg = "RPC server started with pid %s" """ A generic daemon class. Usage: subclass the Daemon class and override the run() method """ def __init__(self, pidfile, stdin='/dev/null', stdout='/dev/null', stderr='/dev/null'): self.stdin = stdin self.stdout = stdout self.stderr = stderr self.pidfile = pidfile log.info("create daemon pidfile at:%s" % self.pidfile) def daemonize(self): """ do the UNIX double-fork magic, see Stevens' "Advanced Programming in the UNIX Environment" for details (ISBN 0201563177) http://www.erlenstar.demon.co.uk/unix/faq_2.html#SEC16 """ #避免产生僵尸进程 signal.signal(signal.SIGCHLD,signal.SIG_IGN) try: pid = os.fork() if pid > 0: # exit first parent log.info("1. fork 1# ---- ppid:%s" % str(os.getpid())) sys.exit(0) #该退出方式会产生SystemExit异常,可以捕获,做一些情场工作,不捕获该进程将会退出 except OSError, e: log.error("fork #1 failed: %d (%s)\n" % (e.errno, e.strerror)) sys.stderr.write("fork #1 failed: %d (%s)\n" % (e.errno, e.strerror)) sys.exit(1) # decouple from parent environment log.info("2. fork 1# ---- pid:%s" % str(os.getpid())) os.chdir("/") os.setsid() os.umask(0) # do second fork try: pid = os.fork() if pid > 0: log.info("3. fork 2# ---- ppid:%s" % str(os.getpid())) os._exit(0) #直接退出进程,不会抛异常 except OSError, e: log.error("fork #2 failed: %d (%s)\n" % (e.errno, e.strerror)) sys.stderr.write("fork #2 failed: %d (%s)\n" % (e.errno, e.strerror)) sys.exit(1) #redirect standard file descriptors log.info("4. fork 2# ---- pid:%s" % str(os.getpid())) sys.stdout.flush() sys.stderr.flush() si = file(self.stdin, 'r') so = file(self.stdout, 'a+') se = file(self.stderr, 'a+', 0) os.dup2(si.fileno(), sys.stdin.fileno()) os.dup2(so.fileno(), sys.stdout.fileno()) os.dup2(se.fileno(), sys.stderr.fileno()) # write pidfile atexit.register(self.delpid) pid = str(os.getpid()) log.info("write pid : %s to pidfile : %s" %(pid, self.pidfile)) file(self.pidfile, 'w+').write("%s\n" % pid) def delpid(self): os.remove(self.pidfile) log.info("do pid : %s os remove(%s)" % (str(os.getpid()), self.pidfile)) def start(self): """ Start the daemon """ # Check for a pidfile to see if the daemon already runs try: pf = file(self.pidfile, 'r') pid = int(pf.read().strip()) pf.close() except IOError: pid = None if pid: message = "pidfile %s already exist. Daemon already running?\n" sys.stderr.write(message % self.pidfile) log.warning(message % self.pidfile) sys.exit(1) # Start the daemon self.daemonize() self.run() def stop(self): """ Stop the daemon """ # Get the pid from the pidfile try: pf = file(self.pidfile, 'r') pid = int(pf.read().strip()) pf.close() except IOError: pid = None if not pid: message = "pidfile %s does not exist. Daemon not running?\n" sys.stderr.write(message % self.pidfile) return # not an error in a restart # Try killing the daemon process try: while 1: os.kill(pid, signal.SIGTERM) time.sleep(0.1) except OSError, err: err = str(err) if err.find("No such process") > 0: if os.path.exists(self.pidfile): os.remove(self.pidfile) log.info("pid : %s delete pidfile : %s" % (str(os.getpid()), self.pidfile)) else: print str(err) sys.exit(1) def restart(self): """ Restart the daemon """ self.stop() self.start() def run(self): """ You should override this method when you subclass Daemon. It will be called after the process has been daemonized by start() or restart(). """
2.创建测试入口
我们的需求是使用协程启动多个守护进程。
* 创建我们两个server1和server2,两个server都是守护进程。
* 使用eventlet.monkey_patch绿化我们的线程
* 使用日志文件详细记录创建守护进程的过程
* 使用命令行开启,关闭我们的服务:python test.py -a start启动所有的server,python test.py stop关闭所有的server
#test.pyimport osimport sysimport timeimport argparseimport loggingimport eventleteventlet.monkey_patch( os=True, select=True, socket=True, thread=False if '--use-debugger' in sys.argv else True, time=True)from daemon import Daemonlog = logging.getLogger(__name__)class MyDaemon(Daemon): def run(self): while True: time.sleep(60) log.info("I am running backend!")def server1(action): # daemon1 = MyDaemon("/tmp/testdeamon1.pid") # log.info("server1 request action : %s" % action) # if action == "start": # daemon1.start() # log.info("started test daemon1") # else: # daemon1.stop() # log.info("stopped test daemon1") try: daemon1 = MyDaemon("/tmp/testdeamon1.pid") log.info("server1 request action : %s" % action) if action == "start": daemon1.start() log.info("started test daemon1") else: daemon1.stop() log.info("stopped test daemon1") except SystemExit, e: log.info("server1 catch SystemExit e:%s" %e)def server2(action): # daemon2 = MyDaemon("/tmp/testdeamon2.pid") # log.info("server2 request action : %s" % action) # if action == "start": # daemon2.start() # log.info("started test daemon2") # else: # daemon2.stop() # log.info("stopped tets daemon2") try: daemon2 = MyDaemon("/tmp/testdeamon2.pid") log.info("server2 request action : %s" % action) if action == "start": daemon2.start() log.info("started test daemon2") else: daemon2.stop() log.info("stopped tets daemon2") except SystemExit, e: log.info("server2 catch SystemExit e:%s" %e)def launch(action): log.info("launch all server request action : %s" % action) threads = [eventlet.spawn(LAUNCH_OPTIONS[option], action) for option in LAUNCH_OPTIONS.keys()] [thread.wait() for thread in threads]LAUNCH_OPTIONS = { 'server1': server1, 'server2': server2}def main(): logging.basicConfig(format="%(asctime)s - [%(filename)s:%(lineno)s - pid:%(process)d] - %(levelname)s - %(message)s", filename='/tmp/test_deamon.log', level=logging.DEBUG) try: parser = argparse.ArgumentParser() parser.add_argument("-s1", help="server1: -s start or -s stop", dest="server1") parser.add_argument("-s2", help="server2: -s start or -s stop", dest="server2") parser.add_argument("-a", help="all server: -a start or -a stop", dest="allserver") args = parser.parse_args() if args.server2: server2(args.server2) elif args.server1: server1(args.server1) elif args.allserver: launch(args.allserver) else: log.info("the args wrong, do not start or stop any server") exit(0) except RuntimeError, e: log.error("catch RuntimeError e:%s" % e) sys.exit(1)if __name__ == '__main__': main()
3.查看我们的日志文件
最重要的就是对日志进行分析了:
从日志的pid的变化可以清楚的知道所有服务创建的过程。
2016-01-06 14:32:30,160 - [test.py:70 - pid:12123] - INFO - launch all server request action : start2016-01-06 14:32:30,161 - [daemon.py:29 - pid:12123] - INFO - create daemon pidfile at:/tmp/testdeamon1.pid2016-01-06 14:32:30,161 - [test.py:37 - pid:12123] - INFO - server1 request action : start2016-01-06 14:32:30,162 - [daemon.py:42 - pid:12123] - INFO - 1. fork 1# ---- ppid:121232016-01-06 14:32:30,162 - [daemon.py:50 - pid:12124] - INFO - 2. fork 1# ---- pid:121242016-01-06 14:32:30,162 - [test.py:45 - pid:12123] - INFO - server1 catch SystemExit e:02016-01-06 14:32:30,162 - [daemon.py:29 - pid:12123] - INFO - create daemon pidfile at:/tmp/testdeamon2.pid2016-01-06 14:32:30,162 - [test.py:59 - pid:12123] - INFO - server2 request action : start2016-01-06 14:32:30,162 - [daemon.py:59 - pid:12124] - INFO - 3. fork 2# ---- ppid:121242016-01-06 14:32:30,162 - [daemon.py:67 - pid:12125] - INFO - 4. fork 2# ---- pid:121252016-01-06 14:32:30,163 - [daemon.py:42 - pid:12123] - INFO - 1. fork 1# ---- ppid:121232016-01-06 14:32:30,163 - [daemon.py:80 - pid:12125] - INFO - write pid : 12125 to pidfile : /tmp/testdeamon1.pid2016-01-06 14:32:30,163 - [test.py:67 - pid:12123] - INFO - server2 catch SystemExit e:02016-01-06 14:32:30,163 - [daemon.py:50 - pid:12126] - INFO - 2. fork 1# ---- pid:121262016-01-06 14:32:30,164 - [daemon.py:59 - pid:12126] - INFO - 3. fork 2# ---- ppid:121262016-01-06 14:32:30,164 - [daemon.py:67 - pid:12127] - INFO - 4. fork 2# ---- pid:121272016-01-06 14:32:30,165 - [daemon.py:80 - pid:12127] - INFO - write pid : 12127 to pidfile : /tmp/testdeamon2.pid2016-01-06 14:32:30,165 - [daemon.py:29 - pid:12125] - INFO - create daemon pidfile at:/tmp/testdeamon2.pid2016-01-06 14:32:30,165 - [test.py:59 - pid:12125] - INFO - server2 request action : start2016-01-06 14:32:30,166 - [daemon.py:103 - pid:12125] - WARNING - pidfile /tmp/testdeamon2.pid already exist. Daemon already running?2016-01-06 14:32:30,166 - [test.py:67 - pid:12125] - INFO - server2 catch SystemExit e:12016-01-06 14:33:30,181 - [test.py:24 - pid:12127] - INFO - I am running backend!2016-01-06 14:33:30,212 - [test.py:24 - pid:12125] - INFO - I am running backend!2016-01-06 14:34:30,237 - [test.py:24 - pid:12127] - INFO - I am running backend!2016-01-06 14:34:30,267 - [test.py:24 - pid:12125] - INFO - I am running backend!2016-01-06 14:35:30,266 - [test.py:24 - pid:12127] - INFO - I am running backend!2016-01-06 14:35:30,312 - [test.py:24 - pid:12125] - INFO - I am running backend!
4.总结
TODO
5. 参考
[Python daemon process]http://code.activestate.com/recipes/278731/
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