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Philippe C. Martin
pmartin at snakecard.com
Wed Oct 19 09:49:33 EDT 2005
Thanks again, So apache uses expat_1.95.7 and python (1, 95, 8) I will try to install expat_1.95.8 and see what happens. Regards, Philippe On Wednesday 19 October 2005 04:16 am, Graham Dumpleton wrote: > Philippe C. Martin wrote .. > > > Got it I think: you mean more than one library are on my disk ? > > Not quite. The version embedded in the pyexpat module of Python is what > is effectively called statically linked. The libexpat.so in your lib > directory would be dynamically loaded as a shared library at some point > because of some dependency on that library by something else. Usually > this is Apache itself and it will get loaded as soon as Apache is started. > > For those who understand what I am talking about, yes I know that the > Python module is dynamically loaded into Python, but the expat part is > statically linked into the Python module .so which is loaded. > > > If so, that's the only I found in the LIB path: > > /usr/lib/libexpat.so.0.5.0. > > > > So that would mean that apache and python use the same right ? > > No. When Python is run from the command line and pyexpat is imported, > it uses the version statically linked into the Python module .so. When > Apache starts up it will load the libexpat.so from lib. > > Now, when mod_python is run in the context of Apache, when the > pyexpat module is imported, because Apache has already loaded libexpat.so > from the lib directory, the version of expat statically linked into the > Python module .so is actually ignored and it uses the version that Apache > had already loaded. > > Going back to my machine here (different one this time), from command > line: > > grahamd at fiona:public_html$ python > Python 2.3.5 (#1, Aug 12 2005, 10:35:05) > [GCC 3.3.2] on sunos5 > Type "help", "copyright", "credits" or "license" for more information. > > >>> import pyexpat > >>> pyexpat.version_info > > (1, 95, 7) > > If I run "ldd" on the Apache httpd program to see what version of libexpat > it is using I get: > > grahamd at fiona:public_html$ ldd /usr/local/sys/apache/bin/httpd > libaprutil-0.so.0 => /usr/local/lib/libaprutil-0.so.0 > libexpat.so.0 => /usr/local/lib/libexpat.so.0 > libapr-0.so.0 => /usr/local/lib/libapr-0.so.0 > libsendfile.so.1 => /usr/lib/libsendfile.so.1 > librt.so.1 => /usr/lib/librt.so.1 > libm.so.1 => /usr/lib/libm.so.1 > libsocket.so.1 => /usr/lib/libsocket.so.1 > libnsl.so.1 => /usr/lib/libnsl.so.1 > libresolv.so.2 => /usr/lib/libresolv.so.2 > libpthread.so.1 => /usr/lib/libpthread.so.1 > libdl.so.1 => /usr/lib/libdl.so.1 > libthread.so.1 => /usr/lib/libthread.so.1 > libc.so.1 => /usr/lib/libc.so.1 > libaio.so.1 => /usr/lib/libaio.so.1 > libmd5.so.1 => /usr/lib/libmd5.so.1 > libmp.so.2 => /usr/lib/libmp.so.2 > /usr/platform/SUNW,UltraAX-i2/lib/libc_psr.so.1 > /usr/platform/SUNW,UltraAX-i2/lib/libmd5_psr.so.1 > > The version number on the library itself is useless, so run "strings" > command to get the version number out of the library itself. > > grahamd at fiona:public_html$ strings /usr/local/lib/libexpat.so.0 | grep > expat_ expat_1.95.2 > > Thus Apache is actually using 1.95.2 whereas the Python module .so for > pyexpat has 1.95.7 embedded into it. > > Now if I create a mod_python.publisher function: > > import pyexpat > > def index(): > return pyexpat.version_info > > and access that page, I get returned: > > 1952 > > I don't quite understand why it is returning an integer rather than a > tuple, it may actually indicate a problem. As one can see though, it is now > actually using 1.95.2 which Apache loaded and not that embedded in the > pyexpat Python module .so. > > The important bit in the above which you didn't do was to run "strings" on > libexpat.so file. Hopefully this will find that string I was picking up > which indicated which version was used. > > BTW, you may be able to confirm whether the expat version is the problem > by simply creating a handler which all it does is import "pyexpat" as > above. If that crashes Apache you probably have a problem as I recollect > that just loading pyexpat will cause the crash, you don't actually have to > use it. This though may only be the case on certain platforms. Another > module you can try importing is "xmlrpclib". This one from memory > definitely crashed Apache for me when I personally had this expat library > version problem on a Linux platform, even without trying to use the > functionality of the module. > > Hope I made it clear this time. > > Graham > > > On Wednesday 19 October 2005 01:33 am, Graham Dumpleton wrote: > > > Philippe C. Martin wrote .. > > > > > > > Hi, > > > > > > > > I'm not sure that's enough info: > > > > > > > > Just for my knowledge, why would that have an effect in apache and > > > > not > > > > > > the > > > > command line ? > > > > > > Imagine if each version of expat used a slightly different structure > > > layout or structure size for something. An object created in the code > > > > of > > > > > the shared library when accessed by C code compiled against the > > > library, but that of a different version, could access the wrong bit of > > > the object and thus follow a bogus pointer and thus crash. > > > > > > Consider this platform I have access to: > > > > > > cinderella$ python > > > Python 2.3.4 (#1, Nov 25 2004, 17:05:37) > > > [GCC 3.3.2] on sunos5 > > > Type "help", "copyright", "credits" or "license" for more information. > > > > > > >>> import pyexpat > > > >>> pyexpat.version_info > > > > > > (1, 95, 7) > > > > > > >>> ^D > > > > > > cinderella$ cd /usr/local/lib > > > cinderella$ strings libexpat.so | grep expat_ > > > expat_1.95.4 > > > > > > The libexpat.so installed on the system has an older version than that > > > compiled into Python. If something causes the libexpat.so to be linked > > > into Apache at the same time as the Python code executing from > > > mod_python is using the embedded one, if there is an incompatability, > > > there may be a problem. > > > > > > In this case, I should be looking at upgrading the one installed in the > > > operating system. > > > > > > Depending on your system the libexpat.so might be in /lib, /usr/lib, > > > /usr/local/lib or elsewhere. > > > > > > Graham > > > > > > > [philippe at pcmsc philippe]$ python > > > > Python 2.4.2 (#1, Oct 18 2005, 04:32:14) > > > > [GCC 3.4.1 (Mandrakelinux 10.1 3.4.1-4mdk)] on linux2 > > > > Type "help", "copyright", "credits" or "license" for more > > > > information. > > > > > > > > >>> import pyexpat > > > > >>> pyexpat.version_info > > > > > > > > (1, 95, 8) > > > > > > > > >>> import expat > > > > > > > > Traceback (most recent call last): > > > > File "<stdin>", line 1, in ? > > > > ImportError: No module named expat > > > > > > > > > > > > > > > > [philippe at pcmsc SC]$ find /usr/lib/python2.4/ -name '*expat*' -exec > > > > ls > > > > > > -l {} > > > > \; > > > > -rw-r--r-- 1 root root 2586 Oct 18 > > > > 04:35 /usr/lib/python2.4/test/output/test_pyexpat > > > > -rw-r--r-- 1 root root 12012 Oct 18 > > > > 04:35 /usr/lib/python2.4/test/test_pyexpat.py > > > > -rw-r--r-- 1 root root 11514 Oct 18 > > > > 04:36 /usr/lib/python2.4/test/test_pyexpat.pyc > > > > -rw-r--r-- 1 root root 11514 Oct 18 > > > > 04:36 /usr/lib/python2.4/test/test_pyexpat.pyo > > > > -rw-r--r-- 1 root root 36379 Oct 18 > > > > 04:35 /usr/lib/python2.4/xml/dom/expatbuilder.py > > > > -rw-r--r-- 1 root root 31084 Oct 18 > > > > 04:36 /usr/lib/python2.4/xml/dom/expatbuilder.pyc > > > > -rw-r--r-- 1 root root 30453 Oct 18 > > > > 04:36 /usr/lib/python2.4/xml/dom/expatbuilder.pyo > > > > -rw-r--r-- 1 root root 112 Oct 18 > > > > 04:35 /usr/lib/python2.4/xml/parsers/expat.py > > > > -rw-r--r-- 1 root root 273 Oct 18 > > > > 04:36 /usr/lib/python2.4/xml/parsers/expat.pyc > > > > -rw-r--r-- 1 root root 273 Oct 18 > > > > 04:36 /usr/lib/python2.4/xml/parsers/expat.pyo > > > > -rw-r--r-- 1 root root 14408 Oct 18 > > > > 04:35 /usr/lib/python2.4/xml/sax/expatreader.py > > > > -rw-r--r-- 1 root root 13471 Oct 18 > > > > 04:36 /usr/lib/python2.4/xml/sax/expatreader.pyc > > > > -rw-r--r-- 1 root root 13471 Oct 18 > > > > 04:36 /usr/lib/python2.4/xml/sax/expatreader.pyo > > > > -rwxr-xr-x 1 root root 436290 Oct 18 > > > > 04:33 /usr/lib/python2.4/lib-dynload/pyexpat.so > > > > > > > > On Wednesday 19 October 2005 12:35 am, Graham Dumpleton wrote: > > > > > Philippe C. Martin wrote .. > > > > > > > > > > > Hi, > > > > > > > > > > > > If any of you wish to look at this: this code works in command > > > > line, > > > > > > and > > > > > > > > > > crashes with apache. Something I'm doing is really anoying > > > > > > minidom. > > > > > > > > > > > > > > > > > > you can fetch the xml file responsible at: > > > > > > www.snakecard.com/mod_python > > > > > > > > > > > > Any help is greatly appreciated. > > > > > > > > > > I you are using a module which does XML processing and it is > > > > > literally crashing, look at what version of the expat libraries > > > > > that are installed on your system. > > > > > > > > > > A problem that can occur is that Python embeds a version of expat > > > > > within its pyexpat module. If an incompatible version of expat is > > > > also > > > > > > > linked in as a shared library, a crash generally occurs. > > > > > > > > > > To determine the version of expat embedded in Python, do from a > > > > > command > > > > > > > > > > line run Python: > > > > > >>> import pyexpat > > > > > >>> pyexpat.version_info > > > > > > > > > > (1, 95, 6) > > > > > > > > > > Ensure that the version of any expat shared library is at least > > > > > newer than that embedded into Python, or the same version if > > > > > possible. > > > > > > > > > > Graham > > > > > > > > -- > > > > ************************************* > > > > Philippe C. Martin > > > > SnakeCard, LLC > > > > www.snakecard.com > > > > +1 405 694 8098 > > > > ************************************* > > > > -- > > ************************************* > > Philippe C. Martin > > SnakeCard, LLC > > www.snakecard.com > > +1 405 694 8098 > > ************************************* -- ************************************* Philippe C. Martin SnakeCard, LLC www.snakecard.com +1 405 694 8098 *************************************
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