New submission from Amaury Forgeot d'Arc <[EMAIL PROTECTED]>:
I found this problem when adding "print" statements to multi-threaded
code. When applying the attached diff to a py3k installation, the output
on screen always contains some garbage.
The following code is an extract of fileio_write (in Modules/_fileio.c),
but the same behavior appears everywhere:
if (!PyArg_ParseTuple(args, "s#", &ptr, &n))
return NULL;
Py_BEGIN_ALLOW_THREADS
errno = 0;
n = write(self->fd, ptr, n);
Py_END_ALLOW_THREADS
io.BufferedWriter calls this function with a bytearray.
In this case, the GIL is released when holding a pointer to the
bytearray data.
But another thread may mutate the bytearray in between, the pointer
becomes stale and can lead to segfaults or funny results.
----------
components: Interpreter Core
files: test_threaded_print.diff
keywords: patch
messages: 68397
nosy: amaury.forgeotdarc
severity: normal
status: open
title: print is not thread safe
type: crash
versions: Python 2.6, Python 3.0
Added file: http://bugs.python.org/file10658/test_threaded_print.diff
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Python tracker <[EMAIL PROTECTED]>
<http://bugs.python.org/issue3139>
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