the pipe reading in Thread dose not work.

Jean-Paul Calderone exarkun at divmod.com
Sun Jun 1 19:19:13 CEST 2008


On Sun, 1 Jun 2008 07:32:39 -0700 (PDT), Leon zhang <leoncamel at gmail.com> wrote:
>
>#!/usr/bin/env python
># -*- coding: utf-8 -*-
>
>import string, sys
>from threading import Thread
>import os
>import time
>
>class test_pipe(Thread):
>    def __init__(self, fd):
>        Thread.__init__(self)
>        self.testfd = fd
>
>    def run(self):
>        print "started thread begin -----"
>        while True:
>            buf = self.testfd.read()
>            print "receive %s" % (buf)
>            time.sleep(1)
>            #print "hoho"
>
>if __name__ == "__main__":
>
>    stdin_r, stdin_w = os.pipe()
>    #stdout_r, stdout_w = pipe()
>
>    f_w = os.fdopen(stdin_w, "w", 0)
>
>    thrd = test_pipe(os.fdopen(stdin_r, "r", 0))
>    thrd.start()
>
>    time.sleep(1)
>
>    while True:
>        f_w.write("help\r\n")
>        time.sleep(1)
>
>    thrd.join()
>--------------------------------------------
>well, I want the following small test about pipe() in thread().
>OK, I write to the pipe in the main thread, and I created a new thread
>for reading from the pipe, then it will print what it received from
>the pipe().
>
>But, it seems it block at the "self.testfd.read()".
>
>So, is there and suggestion and explaination about it?

file.read() reads the entire contents of the file.  Your code never closes
the write end of the pipe, so the read can never succeed - there is always
more for it to read.

Jean-Paul



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