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Jason Carver
ynj0qeh02 at sneakemail.com
Wed Aug 6 13:48:52 EDT 2008
Great, thanks for your help! Is there a good place for me to file a feature
request to have mod_python do something besides crash in this case?
For reference, I have code here to demonstrate the bug and workaround:
def testCrash(req):
"""
Reliably crash server (on 2nd page access)
Open as: http://server/index.py/testCrash
"""
handler = logging.StreamHandler(req)
logging.getLogger('').addHandler( handler )
logging.exception('I crash')
#removing this line will cause an apache crash on the
# second web page access
logging.getLogger('').removeHandler(handler)
I have confirmed that the workaround works reliably for me.
Cheers,
Jason
On Tue, Aug 5, 2008 at 8:36 PM, Graham Dumpleton
graham.dumpleton-at-gmail.com |public mailing list| <
a9ghk53mp50t at sneakemail.com> wrote:
> Just realised what the problem is, rather obvious really.
>
> You are supplying a mod_python request object 'req' to:
>
> logging.getLogger('').addHandler(logging.StreamHandler(req))
>
> You can't do that, as the logging handler you are creating will
> persist beyond the lifetime of the internals of the 'req' object.
> Thus, when logging tries to access it later, it will crash Apache.
>
> In other words, 'req' is just a wrapper for some internal Apache data
> structures which will go away. The mod_python code doesn't currently
> try and protect itself from user code making the mistake of retaining
> the 'req' object longer than it should and then accessing those
> internals.
>
> Graham
>
> 2008/8/6 Jason Carver <ynj0qeh02 at sneakemail.com>:
> > If I try to install mod_python without python 2.5 installed, mod_python
> > refuses, so I assume you mean uninstall all versions of python, then
> install
> > python 2.5.2, then mod_python-3.3.1.win32-py2.5-Apache2.2.exe
> >
> > I did that, with no changes. I get the same Traceback during mod_python
> > install and I can still reproduce the crash reliably.
> >
> > Bug requirements update: It does not matter if I test the req object, it
> > only matters if the req object has something set. So these are the new
> > requirements to reproduce the bug
> >
> > use built in logging module
> > raise Exception
> > call page with variables (ie~ http://localhost/index.py?action=boom)
> > use the following code:
> >
> > import logging
> >
> > def index(req):
> > """Handles all Browser Requests"""
> > try:
> > logging.getLogger('').addHandler( logging.StreamHandler(req) )
> >
> > raise Exception('Goodbye Apache')
> >
> > except Exception, e:
> > logging.exception('I crash')
> > raise
> >
> > So there seems to be some kind of three way interaction between the
> logging
> > module, the apache req module, and exception handling. If any one of the
> > three are not involved, apache does not crash...
> >
> > For now I can use a home-grown logger to get around the bug, but I hate
> to
> > build code that already exists and make future developers have to learn
> my
> > logger instead of the built-in one.
> >
> > Cheers,
> > Jason
> >
> > On Mon, Aug 4, 2008 at 9:44 PM, Graham Dumpleton
> > graham.dumpleton-at-gmail.com |public mailing list|
> > <a9ghk53mp50t at sneakemail.com> wrote:
> >>
> >> Please use reply-all and keep discussion on the list, don't reply just
> to
> >> me.
> >>
> >> Have you tried uninstalling all versions of Python and mod_python
> >> first and then install it? Ie., don't install when you have existing
> >> versions on the system.
> >>
> >> When installing packages, are you doing it as a user with
> >> administrator privileges?
> >>
> >> Graham
> >>
> >> 2008/8/5 <ynj0qeh02 at sneakemail.com>:
> >> > Unfortunately, when I tried to install the mod_python 3.3.1 for 2.5 I
> >> > got
> >> > this traceback:
> >> > Traceback (most recent call last):
> >> > File "boot_com_servers.py", line 21, in <module>
> >> > File "C:\Python25\Lib\site-packages\pythoncom.py", line 3, in
> <module>
> >> > pywintypes.__import_pywin32_system_module__("pythoncom",
> globals())
> >> > File "C:\Python25\Lib\site-packages\win32\Lib\pywintypes.py", line
> 98,
> >> > in
> >> > __import_pywin32_system_module__
> >> > ('.dll', 'rb', imp.C_EXTENSION))
> >> > ImportError: DLL load failed: The specified procedure could not be
> >> > found.
> >> >
> >> > and when I try to start apache 2 anyway, it says "The requested
> >> > operation
> >> > has failed!"
> >> >
> >> > That's why I was using the version for 2.4.
> >> >
> >> > On Mon, Aug 4, 2008 at 9:21 PM, Graham Dumpleton
> >> > graham.dumpleton-at-......... |public mailing list| <...> wrote:
> >> >>
> >> >> 2008/8/5 <ynj0qeh02 at sneakemail.com>:
> >> >> > Thanks for the quick reply! Answers inline...
> >> >> >
> >> >> > On Mon, Aug 4, 2008 at 7:28 PM, Graham Dumpleton
> >> >> > graham.dumpleton-at-......... |public mailing list| <...> wrote:
> >> >> >>
> >> >> >> What operating system? What version of Python? What version of
> >> >> >> mod_python?
> >> >> >
> >> >> > I am on Windows XP SP3 using Python 2.5 in mod_python 3.3.1
> >> >> >
> >> >> > I hacked the binary to use 2.5 on Windows, but the same problem is
> >> >> > reproducible on Ubuntu 7.10 using the latest source from svn
> compiled
> >> >> > with
> >> >> > python 2.5.
> >> >> >
> >> >> >> What startup messages for mod_python are in the Apache error log?
> >> >> >
> >> >> >
> >> >> > [Mon Aug 04 20:03:21 2008] [notice] Server built: Nov 7 2007
> >> >> > 11:48:48
> >> >> > [Mon Aug 04 20:03:21 2008] [notice] Parent: Created child process
> >> >> > 27164
> >> >> > [Mon Aug 04 20:03:22 2008] [error] python_init: Python version
> >> >> > mismatch,
> >> >> > expected '2.4.3', found '2.5'.
> >> >>
> >> >> This is why it is probably breaking. Install mod_python compiled
> >> >> against Python 2.5. The version you are using was compiled against
> >> >> older version of Python.
> >> >>
> >> >> Fix your installation and try again.
> >> >>
> >> >> Do you get similar warnings on your other platform as well?
> >> >>
> >> >> Graham
> >> >>
> >> >> > [Mon Aug 04 20:03:22 2008] [error] python_init: Python executable
> >> >> > found
> >> >> > 'C:\\xampp\\apache\\bin\\apache.exe'.
> >> >> > [Mon Aug 04 20:03:22 2008] [error] python_init: Python path being
> >> >> > used
> >> >> > 'C:\\Program
> >> >> >
> >> >> >
> >> >> >
> Files\\OpenLibraries\\python;C:\\WINDOWS\\system32\\python25.zip;C:\\Python25\\Lib;C:\\Python25\\DLLs;C:\\Python25\\Lib\\lib-tk;;C:\\xampp\\apache\\bin'.
> >> >> > [Mon Aug 04 20:03:22 2008] [notice] mod_python: Creating 8 session
> >> >> > mutexes
> >> >> > based on 0 max processes and 250 max threads.
> >> >> >
> >> >> >>
> >> >> >>
> >> >> >> What is the mod_python configuration you have in Apache
> >> >> >> configuration
> >> >> >> files?
> >> >> >
> >> >> >
> >> >> > PythonOption mod_python.mutex_directory "/pytmp"
> >> >> > PythonOption mod_python.mutex_locks 8
> >> >> >
> >> >> > AliasMatch ^/slique(.*) 'C:/Documents and
> >> >> > Settings/Jason/My
> >> >> > Documents/Coding/eclipse-workspace/slique-dev/src/$1'
> >> >> >
> >> >> > <Directory 'C:/Documents and Settings/Jason/My
> >> >> > Documents/Coding/eclipse-workspace/slique-dev/src'>
> >> >> > Options Indexes ExecCGI FollowSymLinks MultiViews
> >> >> > AllowOverride All
> >> >> >
> >> >> > AddHandler mod_python .py
> >> >> > PythonHandler mod_python.publisher
> >> >> > PythonDebug On
> >> >> > PythonPath "sys.path + ['C:/Documents and Settings/Jason/My
> >> >> > Documents/Coding/eclipse-workspace/slique-dev/src']"
> >> >> >
> >> >> > </Directory>
> >> >> >
> >> >> >>
> >> >> >>
> >> >> >> Specifically, are you setting PythonPath directive in really
> strange
> >> >> >> ways?
> >> >> >
> >> >> > PythonPath is set this way
> >> >> > PythonPath "sys.path + ['C:/Documents and Settings/Jason/My
> >> >> > Documents/Coding/eclipse-workspace/slique-dev/src']"
> >> >> >
> >> >> >>
> >> >> >>
> >> >> >> Does it happen if you don't use the 'logging' module?
> >> >> >
> >> >> > If I comment out logging.exception('I crash'), then the traceback
> >> >> > prints
> >> >> > to
> >> >> > screen as expected.
> >> >> >
> >> >> >>
> >> >> >> Graham
> >> >> >>
> >> >> >> 2008/8/5 Jason Carver <ynj0qeh02 at sneakemail.com>:
> >> >> >> > Here is code that consistently crashes Apache for me:
> >> >> >> >
> >> >> >> > import logging
> >> >> >> >
> >> >> >> > def index(req):
> >> >> >> > """Handles all Browser Requests"""
> >> >> >> > try:
> >> >> >> > reqHandler = logging.StreamHandler(req)
> >> >> >> > logging.getLogger('').addHandler(reqHandler)
> >> >> >> > if req.form.has_key('action'):
> >> >> >> > raise Exception('Goodbye Apache')
> >> >> >> > except Exception, e:
> >> >> >> > logging.exception('I crash')
> >> >> >> > raise
> >> >> >> >
> >> >> >> > Now just go to the site with /?action=dosomething and it will
> >> >> >> > crash
> >> >> >> >
> >> >> >> > Removing the if statement, the exception, or the logger are all
> >> >> >> > ways
> >> >> >> > of
> >> >> >> > alleviating the crash, but none of them should be necessary.
> >> >> >> >
> >> >> >> > Cheers,
> >> >> >> > Jason
> >> >> >> >
> >> >> >> > On Mon, Aug 4, 2008 at 2:51 PM, Jason Carver
> >> >> >> > <ynj0qeh02 at sneakemail.com>
> >> >> >> > wrote:
> >> >> >> >>
> >> >> >> >> Hi all,
> >> >> >> >>
> >> >> >> >> I am having the craziest error, confirmed on both a LAMPython
> and
> >> >> >> >> WAMPython setup: exceptions in mod_python are causing Apache to
> >> >> >> >> crash
> >> >> >> >> hard.
> >> >> >> >> Even stranger is that the exceptions have to meet a few
> specific
> >> >> >> >> conditions
> >> >> >> >> to cause Apache to crash.
> >> >> >> >>
> >> >> >> >> As best I can tell those conditions include:
> >> >> >> >>
> >> >> >> >> raising an exception (this problem always goes away if the
> >> >> >> >> exception
> >> >> >> >> is
> >> >> >> >> commented out)
> >> >> >> >> having the exception be inside an if-block that tests a
> >> >> >> >> dictionary
> >> >> >> >> (the
> >> >> >> >> problem goes away if I do something like """if 'hello' ==
> >> >> >> >> 'hello':
> >> >> >> >> raise
> >> >> >> >> Exception('goodbye')""")
> >> >> >> >> catching the exception and logging it using the python built-in
> >> >> >> >> logging.exception(e) (the problem goes away if I comment out
> the
> >> >> >> >> logger)
> >> >> >> >>
> >> >> >> >> Apache does not write anything to its error.log, so it was a
> bit
> >> >> >> >> of
> >> >> >> >> an
> >> >> >> >> adventure to discover all these elements.
> >> >> >> >>
> >> >> >> >> Any ideas?
> >> >> >> >>
> >> >> >> >> Cheers,
> >> >> >> >> Jason
> >> >> >> >
> >> >> >> > _______________________________________________
> >> >> >> > Mod_python mailing list
> >> >> >> > Mod_python at modpython.org
> >> >> >> > http://mailman.modpython.org/mailman/listinfo/mod_python
> >> >> >> >
> >> >> >> >
> >> >> >
> >> >> >
> >> >
> >> >
> >
> >
> > _______________________________________________
> > Mod_python mailing list
> > Mod_python at modpython.org
> > http://mailman.modpython.org/mailman/listinfo/mod_python
> >
> >
> _______________________________________________
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>
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