货叉:关闭所有打开的插座 [英] fork: close all open sockets

问题描述

我正在使用multiprocessing.Pool.map，它分叉当前进程.

I am using multiprocessing.Pool.map, which forks the current process.

我的理解是，默认情况下，分叉时会从主进程中复制所有文件描述符(包括套接字).主进程本身是一个Web服务器(使用 cherrypy )，因此这会对开放端口等造成严重破坏.分叉的进程实际上只在服务器所包含的一个库中做一些 CPU繁重的数字正在使用-与网络/插座部分无关.

My understanding is that by default, all file descriptors including sockets are copied from the master process when forking. The master process itself is a web server (using cherrypy), so this wreaks havoc with open ports etc. The forked processes are really only doing some CPU-heavy numerical stuff inside one of the libraries that the server is using -- nothing to do with the web/socket part.

是否有一种简单的方法来自动关闭新进程中的所有套接字?还是另一种避免派生CherryPy服务器问题的方法?

Is there an easy way to automatically close all sockets in the new processes? Or another way to avoid issues with forking a CherryPy server?

使用CherryPy 3.2.2，Python 2.7；必须在Linux和OS X上运行.

Using CherryPy 3.2.2, Python 2.7; must work on Linux and OS X.

推荐答案

POSIX不包括列出或关闭一系列文件描述符的明智方法.

POSIX does not include a sensible way to list or close a range of file descriptors.

因此，我们必须遍历整个范围(例如3到1023)，一次关闭一个文件描述符.

So we have to loop over the full range (like from 3 to 1023), closing the file descriptors one at a time.

或者，如果我们具有/proc文件系统，则可以读取/proc/self/fd中打开的文件描述符的列表，然后仅关闭它们.这比关闭所有可能的文件描述符更快.

Or, if we have a /proc file system, we can read the list of open file descriptors in /proc/self/fd and close just those. This can be quicker than closing all possible file descriptors.

import os

def close_files(fd_min=3, fd_max=-1):
    if os.path.exists('/proc/self/fd'):
        close_files_with_procfs(fd_min, fd_max)
    else:
        close_files_exhaustively(fd_min, fd_max)

def close_files_exhaustively(fd_min=3, fd_max=-1):
    import resource
    fd_top = resource.getrlimit(resource.RLIMIT_NOFILE)[1] - 1
    if fd_max == -1 or fd_max > fd_top:
        fd_max = fd_top
    for fd in range(fd_min, fd_max+1):
        try:
            os.close(fd)
        except OSError:
            pass

def close_files_with_procfs(fd_min=3, fd_max=-1):
    for nm in os.listdir("/proc/self/fd"):
        if nm.startswith('.'):
            continue
        fd = int(nm)
        if fd >= fd_min and (fd_max == -1 or fd < fd_max):
            try:
                os.close(fd)
            except OSError:
                pass

def timereps(reps, func):
    from time import time
    start = time()
    for i in range(0, reps):
        func()
    end = time()
    return (end - start) / reps

print "close_files: %f" % timereps(100, lambda: close_files())
print "close_files_exhaustively: %f" % timereps(100, lambda: close_files_exhaustively())
print "close_files_with_procfs: %f" % timereps(1000, lambda: close_files_with_procfs())

在我的系统上:

$ python ./close_fds.py 
close_files: 0.000094
close_files_exhaustively: 0.010151
close_files_with_procfs: 0.000039

这篇关于货叉:关闭所有打开的插座的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！