当我听到多线程编程时，我想到了加速我的程序的机会，但事实并非如此吗？
import eventlet
from eventlet.green import socket
from iptools import IpRangeList
class Scanner(object):
def __init__(self, ip_range, port_range, workers_num):
self.workers_num = workers_num or 1000
self.ip_range = self._get_ip_range(ip_range)
self.port_range = self._get_port_range(port_range)
self.scaned_range = self._get_scaned_range()
def _get_ip_range(self, ip_range):
return [ip for ip in IpRangeList(ip_range)]
def _get_port_range(self, port_range):
return [r for r in range(*port_range)]
def _get_scaned_range(self):
for ip in self.ip_range:
for port in self.port_range:
yield (ip, port)
def scan(self, address):
try:
return bool(socket.create_connection(address))
except:
return False
def run(self):
pool = eventlet.GreenPool(self.workers_num)
for status in pool.imap(self.scan, self.scaned_range):
if status:
yield True
def run_std(self):
for status in map(self.scan, self.scaned_range):
if status:
yield True
if __name__ == '__main__':
s = Scanner(('127.0.0.1'), (1, 65000), 100000)
import time
now = time.time()
open_ports = [i for i in s.run()]
print 'Eventlet time: %s (sec) open: %s' % (now - time.time(),
len(open_ports))
del s
s = Scanner(('127.0.0.1'), (1, 65000), 100000)
now = time.time()
open_ports = [i for i in s.run()]
print 'CPython time: %s (sec) open: %s' % (now - time.time(),
len(open_ports))
并且结果：
Eventlet time: -4.40343403816 (sec) open: 2
CPython time: -4.48356699944 (sec) open: 2
我的问题是，如果我在服务器上运行此代码并设置更多的工作线程，它比CPython版本会更快吗？线程的优点是什么？
附加信息：我已经使用原始的CPython线程重写了应用程序。
import socket
from threading import Thread
from Queue import Queue
from iptools import IpRangeList
class Scanner(object):
def __init__(self, ip_range, port_range, workers_num):
self.workers_num = workers_num or 1000
self.ip_range = self._get_ip_range(ip_range)
self.port_range = self._get_port_range(port_range)
self.scaned_range = [i for i in self._get_scaned_range()]
def _get_ip_range(self, ip_range):
return [ip for ip in IpRangeList(ip_range)]
def _get_port_range(self, port_range):
return [r for r in range(*port_range)]
def _get_scaned_range(self):
for ip in self.ip_range:
for port in self.port_range:
yield (ip, port)
def scan(self, q):
while True:
try:
r = bool(socket.create_conection(q.get()))
except Exception:
r = False
q.task_done()
def run(self):
queue = Queue()
for address in self.scaned_range:
queue.put(address)
for i in range(self.workers_num):
worker = Thread(target=self.scan,args=(queue,))
worker.setDaemon(True)
worker.start()
queue.join()
if __name__ == '__main__':
s = Scanner(('127.0.0.1'), (1, 65000), 5)
import time
now = time.time()
s.run()
print time.time() - now
结果是：
Cpython's thread: 1.4 sec
我认为这是一个非常好的结果。我将nmap扫描时间作为标准：
$ nmap 127.0.0.1 -p1-65000
Starting Nmap 5.21 ( http://nmap.org ) at 2012-10-22 18:43 MSK
Nmap scan report for localhost (127.0.0.1)
Host is up (0.00021s latency).
Not shown: 64986 closed ports
PORT STATE SERVICE
53/tcp open domain
80/tcp open http
443/tcp open https
631/tcp open ipp
3306/tcp open mysql
6379/tcp open unknown
8000/tcp open http-alt
8020/tcp open unknown
8888/tcp open sun-answerbook
9980/tcp open unknown
27017/tcp open unknown
27634/tcp open unknown
28017/tcp open unknown
39900/tcp open unknown
Nmap done: 1 IP address (1 host up) scanned in 0.85 seconds
我的问题是：Eventlet 中的线程实现方式是什么？我能理解这不是普通的线程，而是 Eventlet 的一种特殊实现。为什么它们不能加速任务执行？
许多重要的项目，如 OpenStack 等，使用 Eventlet。但为什么呢？是否只是为了以异步方式执行大量查询操作，还是有其他原因？