def log_search(self, logfile, search_content, timeout=10):

        import time

        import subprocess

        import select

        import signal

        import os

        f = subprocess.Popen(['tail', '-F', logfile], stdout=subprocess.PIPE, stderr=subprocess.PIPE)

        p = select.poll()

        p.register(f.stdout)

        try:

            while timeout>0:

                if p.poll(500):   # millisecond timeout

                    while True:

                        line = f.stdout.readline()

                        if line:

                            if search_content in line:

                                return True

                        else:  # no content read out

                            break

                time.sleep(1)

                timeout -= 1

            else:

                return False

        finally:

            print('unregister')

            p.unregister(f.stdout)

            print('kill pid')

            os.kill(f.pid, signal.SIGKILL)