RE: python.exe vs pythonw.exe difference?

Discussion in 'Python' started by Tim Peters, Mar 2, 2004.

  1. Tim Peters

    Tim Peters Guest

    [moving this from comp.lang.python to zope-dev; it really belongs on a
    Zope list, although schemes to change what pythonw does probably belong
    on python-dev]

    [Emile van Sebille <>]
    >> I've possibly narrowed a problem I'm having running zope as a service
    >> on winxp pro sp 1 in that when started from a command line as:
    >>
    >> c:\zope\v27\lib\python\python.exe \

    c:\zope\v27\lib\python\zope\startup\run.py -C \
    c:\zope\v27\instance\etc\zope.conf

    [tim inserted backslashes above, to make the line structure clear]

    >> it starts up just fine (although now running from the console).
    >>
    >> But when I start it with:
    >>
    >> c:\zope\v27\lib\python\pythonw.exe \

    c:\zope\v27\lib\python\zope\startup\run.py -C \
    c:\zope\v27\instance\etc\zope.conf
    >>
    >> it dies after about 30 seconds.
    >>
    >> It wouldn't surprise me that I'm doing something it doesn't like (I'm
    >> spawning additional processes from within a product but it worked
    >> fine with 2.5),


    It's unclear what "it" means, in "it wworked fine with 2.5". For example,
    do you mean that the second command line, using pythonw.exe explicitly from
    a DOS box worked fine, or do you mean that running Zope as a service on XP
    Pro SP1 worked fine, or ...?

    >> but I'm somewhat at a loss as to debugging it in> that when run as a
    >> console app it works fine, but when run windowless it doesn't.


    Did you look in your Zope log file(s) for tracebacks?

    >> Do I have to write out check points to a file? or is there some way
    >> to use Mark Hammonds process debugging tools? Or is this a bug,
    >> known or otherwise?


    [Thomas Heller]
    > It has been reported that writing to the original sys.stdout (and
    > maybe also sys.stderr) sooner or later raises an IOError when running
    > pythonw.exe, unless these are redirected. Could this be the problem?


    It could, although I have no idea what WinXP does (and don't have access to
    XP). Here's a Python program to try:

    """
    import sys
    if 1: # edit to 1 for stdout, 0 for stderr
    console = sys.stdout
    else:
    console = sys.stderr

    import traceback
    tb = file('tb.txt', 'w')

    try:
    i = 0
    while True:
    i += 1
    console.write('.')
    except:
    print >> tb, "Died when trying to write byte", i
    traceback.print_exc(file=tb)
    tb.close()
    """

    Under Win98SE, and regardless of whether it writes to stdout or stderr, it
    dies when run under pythonw, and tb.txt contains this after:

    Died when trying to write byte 4097
    Traceback (most recent call last):
    File "wr.py", line 14, in ?
    console.write('.')
    IOError: [Errno 9] Bad file descriptor

    The point of pythonw.exe is that no console is created or inherited, and the
    default stdin, stdout and stderr provided by MS C in that case are unusable
    (although the output flavors can appear to be usable until some secret MS
    limit is exceeded -- at least under Win98SE).
    Tim Peters, Mar 2, 2004
    #1
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