Is Python open(file,vr) supposed to update atime?

Question

Whenever I open() a file with Python, the last access time is not updated, that's very odd :

If I open with r/rb nothing changes if I stat the file

If I open with w/r+ or a the ctime and mtime update properly but not atime

It doesn't look like it is a filesystem problem (which is ext3 in this case) because if I touch or cat the file it does update properly.

I haven't been able to find a lot of information about it; is it supposed to behave this way or is there something wrong?

Answer 1

Please try running mount, and see, if noatime flag is used on the mounted fs. Also, if your kernel is fresh enough, it's the "relatime" that is set by-default.

The "open()" code is pretty self-explanatory and does not mess with ATIME flags:

/* >> fileutils.c from Python 3.2.3 */

FILE*
_Py_fopen(PyObject *path, const char *mode)
{
#ifdef MS_WINDOWS
    wchar_t wmode[10];
    int usize;

    usize = MultiByteToWideChar(CP_ACP, 0, mode, -1, wmode, sizeof(wmode));
    if (usize == 0)
        return NULL;

    return _wfopen(PyUnicode_AS_UNICODE(path), wmode);
#else
    FILE *f;
    PyObject *bytes = PyUnicode_EncodeFSDefault(path);
    if (bytes == NULL)
        return NULL;

    /* >> Plain fopen(), nothing fancy here. */
    f = fopen(PyBytes_AS_STRING(bytes), mode);
    Py_DECREF(bytes);
    return f;
#endif
}