python判断自身是否正在运行的方法

# coding: utf-8import osimport psutilimport time def write_pid(): pid = os.getpid() fp = open("pid.log",'w') fp.write(str(pid)) fp.close() def read_pid(): if os.path.exists("pid.log"):  fp = open("pid.log",'r')  pid = fp.read()  fp.close()  return pid else:  return False def write_log(log_content): time_now = time.strftime("%Y-%m-%d %H:%M:%S", time.localtime()) log_content = time_now+"---->"+log_content+os.linesep fp = open('recognition.log','a+') fp.write(log_content) fp.close() def run(): pid = read_pid() #print pid pid = int(pid) if pid:  running_pid = psutil.pids()  if pid in running_pid:   log_content = "process is running..."   write_log(log_content)  else:   write_pid()   time.sleep(20) else:  write_pid()  time.sleep(20) if __name__ == "__main__": run()