[New-bugs-announce] [issue9532] pipe.read hang, when calling commands.getstatusoutput in multi-threading code of python 2.4

[denny]

New submission from denny <markfilebat at 126.com>:

Hi all

My environment is python 2.4.4 on linux. I am encountering hang of pipe.read() in commands.getstatusoutput for multi-threading code.

I have spawned several threads which will call commands.getstatusoutput to run cli. However, pipe.read may hang sometimes.
>From lsof, we know some pipe handles are not closed in the parent process, after the child process is stopped.

;; -------------------------- Reproduce steps --------------------------
Below are reproduce steps.
# Create a python script of /tmp/hang.py, whose content is given below.
# Run "service crond stop; python /tmp/hang.py" several times.
# The script may probably hang. From lsof of main.py and crond service, we may find one pipe existing in both processes.
# If we stop crond to close the pipe, the hang of hang.py will be resolved.

;; -------------------------- Code of hang.py --------------------------
#!/usr/bin/python
import commands
import datetime
import time
import os
import thread
import threading

def thread_run1():

    cmd = "hostname"
    print "begin to run command:%s" % (cmd)
    status, output = commands.getstatusoutput(cmd)
    print "pid:%d, name:%s, status:%d, output:%s" % \
        (os.getpid(), threading.currentThread().getName(), status, output)

    cmd = "ifconfig eth0"
    print "begin to run command:%s" % (cmd)
    status, output = commands.getstatusoutput(cmd)
    print "pid:%d, name:%s, status:%d, output:%s" % \
        (os.getpid(), threading.currentThread().getName(), status, output)

    cmd = "ifconfig eth1"
    print "begin to run command:%s" % (cmd)
    status, output = commands.getstatusoutput(cmd)
    print "pid:%d, name:%s, status:%d, output:%s" % \
        (os.getpid(), threading.currentThread().getName(), status, output)

    # cmd = "sh /tmp/subprocess.sh"
    cmd = "echo here1; sleep 2; echo here2; sleep 5"
    print "begin to run command:%s" % (cmd)
    status, output = commands.getstatusoutput(cmd)
    print "pid:%d, name:%s, status:%d, output:%s" % \
        (os.getpid(), threading.currentThread().getName(), status, output)

def thread_run2():

    cmd = "service crond start"
    print "begin to run command:%s" % (cmd)
    status, output = commands.getstatusoutput(cmd)
    print "pid:%d, name:%s, status:%d, output:%s" % \
        (os.getpid(), threading.currentThread().getName(), status, output)

if __name__=='__main__':
    print "main function begins."
    thread_list = []
    for i in xrange(1, 10):
        my_thread = threading.Thread(target = thread_run1)
        thread_list.append(my_thread)

    my_thread = threading.Thread(target = thread_run2)
    thread_list.append(my_thread)

    for t in thread_list:
        t.start()

    time.sleep(10)

    for t in thread_list:
        t.join()

    print "main function ends."

----------
components: Library (Lib)
messages: 113086
nosy: denny
priority: normal
severity: normal
status: open
title: pipe.read hang, when calling commands.getstatusoutput in multi-threading code of python 2.4
type: behavior
versions: 3rd party

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue9532>
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