[Python-bugs-list] [ python-Bugs-768649 ] popen4 doesn't close filedescriptors when in Threads

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Bugs item #768649, was opened at 2003-07-09 13:36
Message generated for change (Tracker Item Submitted) made by Item Submitter
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https://sourceforge.net/tracker/?func=detail&atid=105470&aid=768649&group_id=5470

Category: Python Library
Group: Python 2.2.2
Status: Open
Resolution: None
Priority: 5
Submitted By: martin doudoroff (mdoudoroff)
Assigned to: Nobody/Anonymous (nobody)
Summary: popen4 doesn't close filedescriptors when in Threads

Initial Comment:

Running the following code under Linux will result in a
crash on the 508th thread started. The error is

    OSError: [Errno 24] Too many open files

The nature of the bug seems to be that Python isn't
closing filedescriptors cleanly when running a thread.

---------------------------------------
import os
from threading import Thread

class Crash(Thread):
    def run(self):
        a = os.popen4('ls')
        b = a[1].read()

        # uncommenting these lines fixes the problem
        #     but this isn't really documented as far as
        #     we can tell...
        # a[0].close()
        # a[1].close()

for i in range(1000):
    t = Crash()
    t.start()

    while t.isAlive():
         pass

    print i
---------------------------------------

The same code without threads (Crash as a plain class)
doesn't crash, so the descriptor must be getting taken
care of when the run() method is exited.

import os

class Crash:
    def run(self):
        a = os.popen4('ls')
        b = a[1].read()

for i in range(1000):
    t = Crash()
    t.run()

    print i


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