python在每个独立的进程中运行一个函数

This is a simple function that runs another function in a different process by forking a new process which runs the function and waiting for the result in the parent. This can be useful for releasing resources used by the function such as memory.

这个简单的函数可以同于在单独的进程中运行另外一个函数，这对于释放内存资源非常有用

#!/usr/bin/env python
from __future__ import with_statement
 
import os, cPickle
def run_in_separate_process(func, *args, **kwds):
    pread, pwrite = os.pipe()
    pid = os.fork()
    if pid > 0:
        os.close(pwrite)
        with os.fdopen(pread, 'rb') as f:
            status, result = cPickle.load(f)
        os.waitpid(pid, 0)
        if status == 0:
            return result
        else:
            raise result
    else: 
        os.close(pread)
        try:
            result = func(*args, **kwds)
            status = 0
        except Exception, exc:
            result = exc
            status = 1
        with os.fdopen(pwrite, 'wb') as f:
            try:
                cPickle.dump((status,result), f, cPickle.HIGHEST_PROTOCOL)
            except cPickle.PicklingError, exc:
                cPickle.dump((2,exc), f, cPickle.HIGHEST_PROTOCOL)
        os._exit(0)
 
#an example of use
def treble(x):
    return 3 * x
 
def main():
    #calling directly
    print treble(4)
    #calling in separate process
    print run_in_separate_process(treble, 4)