引入多线程势在必行，那么多线程该如何应用呢？从服务整体可用性考虑，把下载镜像跟重启容器两个操作拆分，下载镜像不影响服务正常提供，完全可以采用多线程，这样整个下载镜像的时间将大大缩短，优化后代码如下：
import threading # 再导入上一个示例里边的Conn类 class DownloadThread(threading.Thread): def __init__(self, host, image_url): threading.Thread.__init__(self) self.host = host self.image_url = image_url def run(self): Conn(self.host).cmd('docker login -u ops -p coffee hub.ops-coffee.cn') r2 = Conn(self.host).cmd('docker pull %s' % self.image_url) if r2.get('state'): self.alive_host = self.host print('---->%s镜像下载完成' % self.host) else: self.alive_host = None print('---->%s镜像下载失败，details：%s' % (self.host, r2.get('message'))) def get_result(self): return self.alive_host if __name__ == '__main__': # 演示代码简化了很多，整体逻辑不变 hostlist = ['10.82.9.47', '10.82.9.48'] image_url = 'ops-coffee:latest' threads = [] for host in hostlist: t = DownloadThread(host, image_url) threads.append(t) for t in threads: t.start() for t in threads: t.join() alive_host = [] for t in threads: alive_host.append(t.get_result()) ## 多线程下载镜像结束 print('---->本项目共有主机%d台，%d台主机下载镜像成功' % (len(hostlist), len(alive_host)))