Python怎么实现父子进程共享文件对象

from multiprocessing import Process, Lock

err_file = 'error1.log'  

err_fd = open(err_file, 'w')

def put(fd):

     print "PUT"

     fd.write("hello, func put writen")

     print "END"

if __name__=='__main__':

    p_list=[]

    for i in range(1):

        p_list.append(Process(target=put, args=(err_fd,)))    

    for p in p_list:

        p.start()

    for p in p_list:

        p.join()

[root@iZ23pynfq19Z ~]# py27 2.py ; cat error1.log

PUT

END

[root@iZ23pynfq19Z ~]#

from multiprocessing import Process, Lock

err_file = 'error1.log'  

err_fd = open(err_file, 'w')

def put(fd):

     print "PUT"

     fd.write("hello, func put writen")

     fd.write("o" * 4075) # 神奇的一行

     print "END"

if __name__=='__main__':

    p_list=[]

    for i in range(1):

        p_list.append(Process(target=put, args=(err_fd,)))    for p in p_list:

        p.start()

    for p in p_list:

        p.join()

[root@iZ23pynfq19Z ~]# py27 2.py ; cat error1.log

PUT

END

hello, func put write

o....(有4075个)

[root@iZ23pynfq19Z ~]#

取自Python官网Document:

open(name[, mode[, buffering]])

  ...

  The optional buffering argument specifies the file’s desired buffer size: 0 means unbuffered,

  1 means line buffered, any other positive value means use a buffer of (approximately) that

  size (in bytes). A negative buffering means to use the system default, which is usually line

  buffered for tty devices and fully buffered for other files. If omitted, the system default is

  used. [2]

multiprocessing/Processing.py

    def start(self):

        '''

        Start child process

        '''

        assert self._popen is None, 'cannot start a process twice'

        assert self._parent_pid == os.getpid(),

               'can only start a process object created by current process'

        assert not _current_process._daemonic,

               'daemonic processes are not allowed to have children'

        _cleanup()

        if self._Popen is not None:

            Popen = self._Popen

        else:

            from .forking import Popen

        self._popen = Popen(self)

        _current_process._children.add(self)

multiprocessing/forking.py

    class Popen(object):

        def __init__(self, process_obj):

            sys.stdout.flush()

            sys.stderr.flush()

            self.returncode = None

            self.pid = os.fork()

            if self.pid == 0:

                if 'random' in sys.modules:

                    import random

                    random.seed()

                code = process_obj._bootstrap()

                sys.stdout.flush()

                sys.stderr.flush()

                os._exit(code)

multiprocessing/forking.py

    class Popen(object):

        def __init__(self, process_obj):

            sys.stdout.flush()

            sys.stderr.flush()

            self.returncode = None

            self.pid = os.fork()

            if self.pid == 0:

                if 'random' in sys.modules:

                    import random

                    random.seed()

                code = process_obj._bootstrap()

                sys.stdout.flush()

                sys.stderr.flush()

                #os._exit(code)

                sys.exit(code)

[root@iZ23pynfq19Z ~]# python 2.py ; cat error1.log

PUT

END

hello, func put write