[mod_python] Help about apache mod_python Segmentation fault

Graham Dumpleton graham.dumpleton at gmail.com
Mon Mar 3 22:56:37 EST 2008


On 04/03/2008, auther_bin <auther_bin at 21cn.com> wrote:
> Hi, Graham Dumpleton!
>
>  Thanks for your help first, but the problem is still there. here is my testing steps:
>
>  I read carefully of the URL you give me: http://code.google.com/p/modwsgi/wiki/InstallationIssues
>  and re-compiling the python2.5 --enable-shared, and get python libpython2.5.so install, when I testing python like:
>
>  =====================================================================
>  # python
>  Python 2.5 (r25:51908, Mar  4 2008, 08:56:31)
>  [GCC 3.4.4] on linux2
>  Type "help", "copyright", "credits" or "license" for more information.
>  >>> testi=1
>  >>> if testi==1:
>  ...  print "hello test"
>  ...
>  hello test
>  >>> <ctl-d>
>  # ldd python
>                 libpython2.5.so.1.0 => not found

Where is your libpython2.5.so installed? Not your sylimk, but what the
symlink points at.

>         libpthread.so.0 => /lib/libpthread.so.0 (0x40023000)
>         libdl.so.0 => not found
>         libutil.so.0 => not found
>         libm.so.0 => not found
>         libc.so.0 => not found

Your operating system installation is severely crippled or broken if
these standard libraries cannot be found. Are you stuck with using
uClibc or can you use something else?

>         libc.so.6 => /lib/libc.so.6 (0x40076000)
>         /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
>  # ## for the libs is installed in an embeded path so some of them could not be found
>  # ls -F /bin/lib/python2.5/config

Why is this under /bin/lib? That isn't the standard location for this
sort off stuff and if libpython2.5.so is in /bin/lib it will not be
found.

Graham

>  Makefile         config.c         libpython2.5.a   python.o
>  Setup            config.c.in      [email protected]
>  Setup.local      install-sh*      makesetup*
>  =====================================================================
>
>  when I run "httpd -X" it's still gives an Segmentation fault :(
>  anything else could be found about this crash?
>  or I give you an ssh login to my host :)
>
>  ======= 2008-03-03 wrote =======
>
>
>  >In gdb, instead of 'where', try:
>  >
>  >  thread apply all bt
>  >
>  >in case gdb isn't throwing you into the correct thread context.
>  >
>  >BTW, does the Python on the environment that crashes provide a shared
>  >library? For what I am talking about see:
>  >
>  >  http://code.google.com/p/modwsgi/wiki/InstallationIssues
>  >
>  >This is documentation from mod_wsgi but same problems apply to mod_python.
>  >
>  >Graham
>  >
>  >On 03/03/2008, auther_bin <auther_bin at 21cn.com> wrote:
>  >>
>  >>
>  >> Hi Graham Dumpleton,
>  >>
>  >> And, when I debug in RedHat9 and my embeded
>  >> envirenment, the main process goes
>  >> different!?
>  >>
>  >> in Redhat9, run like:
>  >>
>  >>
>  >> (gdb) b main
>  >> Breakpoint 1 at 0x8067a40: file main.c, line 438.
>  >> (gdb) run -X
>  >> Starting program: /usr/local/apache2/bin/httpd -X
>  >> [New Thread 1076592288 (LWP 1049)]
>  >> [Switching to Thread 1076592288 (LWP 1049)]
>  >>
>  >> Breakpoint 1, main (argc=134642240, argv=0x2) at main.c:438
>  >> 438     {
>  >> (gdb) n
>  >> 272         stat = apr_app_initialize(argc, argv, NULL);
>  >>
>  >> and in my embeded system runs like:
>  >>
>  >>
>  >>
>  >> Breakpoint 1, main (argc=2, argv=0xbffff294)
>  >>     at
>  >> /usr/src/build/snapgear/user/apache/server/main.c:441
>  >> 441         int configtestonly = 0;
>  >> (gdb) n
>  >> 442         const char *confname = SERVER_CONFIG_FILE;
>  >>
>  >>
>  >>
>  >> it seems that, the hosting system doing something for init before the main
>  >> function run, but embeded system do not?
>  >>
>  >> I thinks is here somthing wrong? or there should be some compiling
>  >> parameters I missed?
>  >>
>  >> ======= 2008-02-27 wrote: =======
>  >>
>  >>
>  >> >On 27/02/2008, auther_bin  <auther_bin at 21cn.com > wrote:
>  >> > > Dear friends,
>  >> > >
>  >> > >         When I compiling the apache python mod_python
>  >> and install it into my uClibc
>  >> envirentment,
>  >> but when I
>  >> > >  runing httpd -X, send a very little request with
>  >> index.html it crashed. after some debuging work,
>  >> I find there should be something wrong in mod_python.c
>  >> line(about 1561) which looks like:
>  >> > >  --------------------------------- with my debug
>  >> printing :) ------------------------
>  >> > >  printf("JJJJJJJJ %s - > python_handler\n", phase);
>  >> > >  printf("JJJJJJJJ %x[%d]\n", &req- >per_dir_config,
>  >> (&python_module)- >module_index);
>  >> > >     /* get configuration */
>  >> > >     conf = (py_config *) ap_get_module_config(req-
>  >> >per_dir_config,
>  >> > >
>  >> &python_module);
>  >> > >  printf("JJJJJJJJ a %s conf=%x - > python_handler\n",
>  >> phase,conf);
>  >> > >  .............
>  >> > >  ------------------------------ end source
>  >> --------------------------------------
>  >> > >
>  >> > >  I guess that, there should be a regester error in
>  >> it. with some debug message I print:
>  >> > >  ------------- printing -------------------------------
>  >> > >  JJJJJJJJJ PythonPostReadRequestHandler
>  >> > >  JJJJJJJJ PythonInitHandler - > python_handler
>  >> > >  JJJJJJJJ 820a544[29]
>  >> > >  Segmentation fault
>  >> > >  ------------- end printing ---------------------------
>  >> > >
>  >> > >  any advices pls?
>  >> >
>  >> >Unfortunately that doesn't help much.
>  >> >
>  >> >You need a stack trace to show the true location
>  >> in code.
>  >> >
>  >> >Use procedure documented in section 'Debugging
>  >> Crashes With GDB' of:
>  >> >
>  >> >
>  >> http://code.google.com/p/modwsgi/wiki/DebuggingTechniques
>  >> >
>  >> >to run up httpd inside of gdb and get a stack trace
>  >> of where crash is occurring.
>  >> >
>  >> >This documentation is for mod_wgsi, but same procedure
>  >> used for mod_python.
>  >> >
>  >> >There is a similar procedure documented on Apache
>  >> site, but can't
>  >> >remember where.
>  >> >
>  >> >Graham
>  >> >
>  >> >
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>  >> >
>  >>
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>  >>
>  >>
>  >>                     ÖÂ
>  >> Àñ£¡
>  >> 2008-03-03
>  >>
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>                 2008-03-04
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