New submission from Ribhi Kamal:
I was about to use memory mapping for something when I discovered that the code
example posted on python.org causes python to core dump. %100 reproducible
The steps are really simple.
1- Create a file and map it using mmap.mmap
2- In a while loop, contintously read the file
3- From another process, like bash, continuously write to the file.
After about 5 iterations from the reader, python core dumps.
Reader code (python):
#!/usr/bin/python2.7
import mmap
import time
with open("hello.txt", "wb") as f:
f.write("Hello Python! 1234123412341234\n")
with open("hello.txt", "r+b") as f:
# memory-map the file, size 0 means whole file
mm = mmap.mmap(f.fileno(), 0)
count=0
while count < 100:
mm.seek(0)
print mm.readline()
time.sleep(0.1)
count = count + 1
# close the map
mm.close()
Writer code (linux shell/bash):
#!/bin/bash
count=0
while true
do
((count++))
echo $count > hello.txt
done
Now run the reader, then launch the writer in a terminal. In my case I get the
following output:
>110
>
>462
>
>Bus error (core dumped)
Python 2.7.3
Linux 3.2.0-54-generic #82-Ubuntu SMP Tue Sep 10 20:09:12 UTC 2013 i686 i686
i386 GNU/Linux
Ubuntu 12.04.3 LTS
Intel(R) Core(TM)2 CPU 6300 @ 1.86GHz
--
components: IO
messages: 200820
nosy: rbhkamal
priority: normal
severity: normal
status: open
title: MMAP: Bus error (core dump) under heavy read/write
type: crash
versions: Python 2.7
___
Python tracker
<http://bugs.python.org/issue19337>
___
___
Python-bugs-list mailing list
Unsubscribe:
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
