#!/usr/bin/env python
import sys, os, time, atexit, string
from signal import SIGTERM
class Daemon:
def __init__(self, pidfile, stdin='/dev/null', stdout='/dev/null', stderr='/dev/null'):
#需要获取调试信息，改为stdin='/dev/stdin', stdout='/dev/stdout', stderr='/dev/stderr'，以root身份运行。
self.stdin = stdin
self.stdout = stdout
self.stderr = stderr
self.pidfile = pidfile
def _daemonize(self):
try:
pid = os.fork()
if pid > 0:
#退出主进程
sys.exit(0)
except OSError, e:
sys.stderr.write('fork #1 failed: %d (%s)\n' % (e.errno, e.strerror))
sys.exit(1)
os.chdir("/")
os.setsid()
os.umask(0)
#创建子进程
try:
pid = os.fork()
if pid > 0:
sys.exit(0)
except OSError, e:
sys.stderr.write('fork #2 failed: %d (%s)\n' % (e.errno, e.strerror))
sys.exit(1)
#重定向文件描述符
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())
#创建processid文件
atexit.register(self.delpid)
pid = str(os.getpid())
file(self.pidfile,'w+').write('%s\n' % pid)
def delpid(self):
os.remove(self.pidfile)
def start(self):
#检查pid文件是否存在以探测是否存在进程
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)
sys.exit(1)
#启动监控
self._daemonize()
self._run()
def stop(self):
#从pid文件中获取pid
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 #重启不报错
#杀进程
try:
while 1:
os.kill(pid, SIGTERM)
time.sleep(0.1)
os.system('/opt/modules/hadoop/hadoop-0.20.203.0/bin/hadoop-daemon.sh stop datanode')
os.system('/opt/modules/hadoop/hadoop-0.20.203.0/bin/hadoop-daemon.sh stop tasktracker')
except OSError, err:
err = str(err)
if err.find('No such process') > 0:
if os.path.exists(self.pidfile):
os.remove(self.pidfile)
else:
print str(err)
sys.exit(1)
def restart(self):
self.stop()
self.start()
def _run(self):
while True:
datanode = os.popen('ps -fe | grep "java" | grep "datanode" | grep -v "grep" | wc -l').read().strip()
tasktracker = os.popen('ps -fe | grep "java" | grep "tasktracker" | grep -v "grep" | wc -l').read().strip()
#选出进程中含有java且含有datanode|tasktracker且不含有grep，计算出现行数。修改上面的进程监控语句以适应其他应用需求
if datanode == '0':
os.system('/opt/modules/hadoop/hadoop-0.20.203.0/bin/hadoop-daemon.sh start datanode')
#修改这里的启动命令
if tasktracker == '0':
os.system('/opt/modules/hadoop/hadoop-0.20.203.0/bin/hadoop-daemon.sh start tasktracker')
#修改这里的启动命令
time.sleep(2)
#修改这里的停留时间
if __name__ == '__main__':
daemon = Daemon('/tmp/watch_process.pid')
if len(sys.argv) == 2:
if 'start' == sys.argv[1]:
daemon.start()
elif 'stop' == sys.argv[1]:
daemon.stop()
elif 'restart' == sys.argv[1]:
daemon.restart()
else:
print 'Unknown command'
sys.exit(2)
sys.exit(0)
else:
print 'usage: %s start|stop|restart' % sys.argv[0]
sys.exit(2)