python主循环_修改Python的pyxmpp2中的主循环使其提高性能

引子

之前clubot使用的pyxmpp2的默认mainloop也就是一个poll的主循环,但是clubot上线后资源占用非常厉害,使用strace跟踪发现clubot在不停的poll,查看pyxmpp2代码发现pyxmpp2的poll在使用超时阻塞时使用最小超时时间,而最小超时时间一直是0,所以会变成一个没有超时的非阻塞poll很浪费资源,不打算更改库代码,所以自己仿照poll的mainloop写了一个更加高效的epoll的mainloop

实现

#!/usr/bin/env python

# -*- coding:utf-8 -*-

#

# Author : cold

# E-mail : wh_linux@126.com

# Date : 13/01/06 10:41:31

# Desc : Clubot epoll mainloop

#

from __future__ import absolute_import, division

import select

from pyxmpp2.mainloop.interfaces import HandlerReady, PrepareAgain

from pyxmpp2.mainloop.base import MainLoopBase

from plugin.util import get_logger

class EpollMainLoop(MainLoopBase):

""" Main event loop based on the epoll() syscall on Linux system """

READ_ONLY = (select.EPOLLIN | select.EPOLLPRI | select.EPOLLHUP |

select.EPOLLERR |select.EPOLLET)

READ_WRITE = READ_ONLY | select.EPOLLOUT

def __init__(self, settings = None, handlers= None):

self.epoll = select.epoll()

self._handlers = {}

self._unprepared_handlers = {}

self._timeout = None

self._exists_fd = {}

self.logger = get_logger()

MainLoopBase.__init__(self, settings, handlers)

return

def _add_io_handler(self, handler):

self._unprepared_handlers[handler] = None

self._configure_io_handler(handler)

def _configure_io_handler(self, handler):

if self.check_events():

return

if handler in self._unprepared_handlers:

old_fileno = self._unprepared_handlers[handler]

prepared = self._prepare_io_handler(handler)

else:

old_fileno = None

prepared = True

fileno = handler.fileno()

if old_fileno is not None and fileno != old_fileno:

del self._handlers[old_fileno]

self._exists.pop(old_fileno, None)

self.epoll.unregister(old_fileno)

if not prepared:

self._unprepared_handlers[handler] = fileno

if not fileno:

return

self._handlers[fileno] = handler

events = 0

if handler.is_readable():

events |= self.READ_ONLY

if handler.is_writable():

events |= self.READ_WRITE

if events:

if fileno in self._exists_fd:

self.epoll.modify(fileno, events)

else:

self._exists_fd.update({fileno:1})

self.epoll.register(fileno, events)

def _prepare_io_handler(self, handler):

ret = handler.prepare()

if isinstance(ret, HandlerReady):

del self._unprepared_handlers[handler]

prepared = True

elif isinstance(ret, PrepareAgain):

if ret.timeout is not None:

if self._timeout is not None:

self._timeout = min(self._timeout, ret.timeout)

else:

self._timeout = ret.timeout

prepared = False

else:

raise TypeError("Unexpected result from prepare()")

return prepared

def _remove_io_handler(self, handler):

if handler in self._unprepared_handlers:

old_fileno = self._unprepared_handlers[handler]

del self._unprepared_handlers[handler]

else:

old_fileno = handler.fileno()

if old_fileno is not None:

try:

del self._handlers[old_fileno]

self._exists.pop(old_fileno, None)

self.epoll.unregister(old_fileno)

except KeyError:

pass

def loop_iteration(self, timeout = 60):

next_timeout, sources_handled = self._call_timeout_handlers()

if self.check_events():

return

if self._quit:

return sources_handled

for handler in list(self._unprepared_handlers):

self._configure_io_handler(handler)

if self._timeout is not None:

timeout = min(timeout, self._timeout)

if next_timeout is not None:

timeout = min(next_timeout, timeout)

if timeout == 0:

timeout += 1 # 带有超时的非阻塞,解约资源

events = self.epoll.poll(timeout)

for fd, flag in events:

if flag & (select.EPOLLIN | select.EPOLLPRI | select.EPOLLET):

self._handlers[fd].handle_read()

if flag & (select.EPOLLOUT|select.EPOLLET):

self._handlers[fd].handle_write()

if flag & (select.EPOLLERR | select.EPOLLET):

self._handlers[fd].handle_err()

if flag & (select.EPOLLHUP | select.EPOLLET):

self._handlers[fd].handle_hup()

#if flag & select.EPOLLNVAL:

#self._handlers[fd].handle_nval()

sources_handled += 1

self._configure_io_handler(self._handlers[fd])

return sources_handled

使用

如何使用新的mainloop?只需在实例化Client时传入

mainloop = EpollMainLoop(settings)

client = Client(my_jid, [self, version_provider], settings, mainloop)

这样就会使用epoll作为mainloop

注意

epoll仅仅在Linux下支持

最后

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