最近在研究Python的multiprocessing模块，顺便去了解下Ansible是如何实现并发执行命令的。
在Ansible目录下搜索multiprocessing
cd /usr/lib/python2.6/site-packages/ansible
find -exec grep -l multiprocessing {} \;
只有./runner/__init__.py这个文件里面引用了multiprocessing模块
def _parallel_exec(self, hosts):
‘‘‘ handles mulitprocessing when more than 1 fork is required ‘‘‘
manager = multiprocessing.Manager()
job_queue = manager.Queue()
for host in hosts:
job_queue.put(host)
result_queue = manager.Queue()
try:
fileno = sys.stdin.fileno()
except ValueError:
fileno = None
workers = []
for i in range(self.forks):
new_stdin = None
if fileno is not None:
try:
new_stdin = os.fdopen(os.dup(fileno))
except OSError, e:
# couldn‘t dupe stdin, most likely because it‘s
# not a valid file descriptor, so we just rely on
# using the one that was passed in
pass
prc = multiprocessing.Process(target=_executor_hook,
args=(job_queue, result_queue, new_stdin))
prc.start()
workers.append(prc)
try:
for worker in workers:
worker.join()
except KeyboardInterrupt:
for worker in workers:
worker.terminate()
worker.join()
results = []
try:
while not result_queue.empty():
results.append(result_queue.get(block=False))
except socket.error:
raise errors.AnsibleError("<interrupted>")
return results
# *****************************************************Ansible能够同时对成百上千的服务器同时执行操作，都是通过这个函数实现的，使用Python的多进程模块来提升效率
首先定义一个
参考资料：
本文出自 “Linux SA John” 博客，请务必保留此出处http://john88wang.blog.51cto.com/2165294/1750652
Ansible源码分析之Python的multiprocessing模块使用
原文：http://john88wang.blog.51cto.com/2165294/1750652