需求：寫(xiě)一個(gè)腳本，判斷192.168.11.0/24網(wǎng)絡(luò)里，當(dāng)前在線ip有哪些？

知識(shí)點(diǎn):

1 使用subprocess模塊，來(lái)調(diào)用系統(tǒng)命令，執(zhí)行ping 192.168.11.xxx 命令

2 調(diào)用系統(tǒng)命令執(zhí)行ping命令的時(shí)候，會(huì)有返回值(ping的結(jié)果)，需要用到stdout=fnull, stderr=fnull方法，屏蔽系統(tǒng)執(zhí)行命令的返回值

常規(guī)版本(代碼)

import os
import time
import subprocess
def ping_call():start_time = time.time()fnull = open(os.devnull, 'w')for i in range(1, 256):ipaddr = 'ping 192.168.11.' + str(i)result = subprocess.call(ipaddr + ' -n 2', shell=True, stdout=fnull, stderr=fnull)current_time = time.strftime('%Y%m%d-%H:%M:%S', time.localtime())if result:print('時(shí)間:{} ip地址:{} ping fall'.format(current_time, ipaddr))else:print('時(shí)間:{} ip地址:{} ping ok'.format(current_time, ipaddr))print('程序耗時(shí){:.2f}'.format(time.time() - start_time))fnull.close()
ping_call()

執(zhí)行效果：

上面的執(zhí)行速度非常慢，怎么能讓程序執(zhí)行速度快起來(lái)？

python提供了進(jìn)程，線程，協(xié)程。分別用這三個(gè)對(duì)上面代碼改進(jìn)，提高執(zhí)行效率，測(cè)試一波效率

進(jìn)程池異步執(zhí)行 – 開(kāi)啟20個(gè)進(jìn)程

import os
import time
import subprocess
from multiprocessing import Pool
def ping_call(num):fnull = open(os.devnull, 'w')ipaddr = 'ping 192.168.11.' + str(num)result = subprocess.call(ipaddr + ' -n 2', shell=True, stdout=fnull, stderr=fnull)current_time = time.strftime('%Y%m%d-%H:%M:%S', time.localtime())if result:print('時(shí)間:{} ip地址:{} ping fall'.format(current_time, ipaddr))else:print('時(shí)間:{} ip地址:{} ping ok'.format(current_time, ipaddr))fnull.close()if __name__ == '__main__':start_time = time.time()p = Pool(20)res_l = []for i in range(1, 256):res = p.apply_async(ping_call, args=(i,))res_l.append(res)for res in res_l:res.get()print('程序耗時(shí){:.2f}'.format(time.time() - start_time))

執(zhí)行結(jié)果：

線程池異步執(zhí)行 – 開(kāi)啟20個(gè)線程

import os
import time
import subprocess
from concurrent.futures import ThreadPoolExecutor
def ping_call(num):fnull = open(os.devnull, 'w')ipaddr = 'ping 192.168.11.' + str(num)result = subprocess.call(ipaddr + ' -n 2', shell=True, stdout=fnull, stderr=fnull)current_time = time.strftime('%Y%m%d-%H:%M:%S', time.localtime())if result:print('時(shí)間:{} ip地址:{} ping fall'.format(current_time, ipaddr))else:print('時(shí)間:{} ip地址:{} ping ok'.format(current_time, ipaddr))fnull.close()if __name__ == '__main__':start_time = time.time()thread_pool = ThreadPoolExecutor(20)ret_lst = []for i in range(1, 256):ret = thread_pool.submit(ping_call, i)ret_lst.append(ret)thread_pool.shutdown()for ret in ret_lst:ret.result()print('線程池(20)異步-->耗時(shí){:.2f}'.format(time.time() - start_time))

執(zhí)行結(jié)果：

協(xié)程執(zhí)行—(執(zhí)行多個(gè)任務(wù)，遇到I/O操作就切換)

使用gevent前，需要pip install gevent

from gevent import monkey;monkey.patch_all()
import gevent
import os
import time
import subprocessdef ping_call(num):fnull = open(os.devnull, 'w')ipaddr = 'ping 192.168.11.' + str(num)result = subprocess.call(ipaddr + ' -n 2', shell=True, stdout=fnull, stderr=fnull)current_time = time.strftime('%Y%m%d-%H:%M:%S', time.localtime())if result:print('時(shí)間:{} ip地址:{} ping fall'.format(current_time, ipaddr))else:print('時(shí)間:{} ip地址:{} ping ok'.format(current_time, ipaddr))fnull.close()def asynchronous(): # 異步g_l = [gevent.spawn(ping_call, i) for i in range(1, 256)]gevent.joinall(g_l)if __name__ == '__main__':start_time = time.time()asynchronous()print('協(xié)程執(zhí)行-->耗時(shí){:.2f}'.format(time.time() - start_time))

執(zhí)行結(jié)果：

遇到I/O操作，協(xié)程的效率比進(jìn)程，線程高很多!

總結(jié)：python中，涉及到I/O阻塞的程序中，使用協(xié)程的效率最高

最后附帶協(xié)程池代碼

gevent.pool

from gevent import monkey;monkey.patch_all()
import gevent
import os
import time
import subprocess
import gevent.pooldef ping_call(num):fnull = open(os.devnull, 'w')ipaddr = 'ping 192.168.11.' + str(num)result = subprocess.call(ipaddr + ' -n 2', shell=True, stdout=fnull, stderr=fnull)current_time = time.strftime('%Y%m%d-%H:%M:%S', time.localtime())if result:print('時(shí)間:{} ip地址:{} ping fall'.format(current_time, ipaddr))else:print('時(shí)間:{} ip地址:{} ping ok'.format(current_time, ipaddr))fnull.close()if __name__ == '__main__':start_time = time.time()res_l = []p = gevent.pool.Pool(100)for i in range(1, 256):res_l.append(p.spawn(ping_call, i))gevent.joinall(res_l)print('協(xié)程池執(zhí)行-->耗時(shí){:.2f}'.format(time.time() - start_time))

執(zhí)行結(jié)果: