mapserv segfaults

[John C Cartwright]

Hi Sean,

thanks for the suggestion. here's the output:

(gdb) run
Starting program: /extra/contrib/apache/cgi-bin/mapserv-debug
[Thread debugging using libthread_db enabled]
[New Thread -1218604192 (LWP 19250)]
[Thu Feb 10 09:40:19 2005].204455 msWMSLoadGetMapParams(): enabling
non-square pixels.[Thu Feb 10 09:40:19 2005].208427 msDrawMap(): kicking
into non-square pixel preserving mode.
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1218604192 (LWP 19250)]
0x0095b0d1 in realloc () from /lib/tls/libc.so.6

Here's the query string:

map=/extra/contrib/apache/htdocs/mapserver/wms_wfs/wms.map&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&LAYERS=relief,cities_poly,counties,states,roads

and this is a RedHat ES 3 system (kernel 2.4.21-27.0.1.ELsmp)

Where should I go from here?

Thanks again!

-- john


Sean Gillies wrote:
> John, add a
>
>   DEBUG ON
>
> to the Map-level block in your map config file.  This will write
> messages to stderr, including names of layers being accessed.  This
> should let you know which layer (if any) is associated with the segfault.
>
> Now that you've recompiled, run mapserv under gdb exactly as Steve
> Woodbridge described.  This time gdb should give a more detailed
> description of the location of the memory error including all the
> MapServer functions that have been called.  Give us a look at that and
> we can try to figure out what's going on.
>
> cheers,
> Sean
>
> On Feb 9, 2005, at 5:28 PM, John C Cartwright wrote:
>
>> Thanks, Sean. I recompiled with debugging, can you provide me a little
>> guidance on what would be helpful to get out of gdb?
>>
>> ...
>> Thanks again for your patience and help!
>>
>> -- john
>>
>
>> Sean Gillies wrote:
>>
>>> John,
>>> Looks to me like you need to re-config mapserver with --enable-debug so
>>> that gdb can tell us more about the calling stack.
>>> cheers,
>>> Sean
>>> On Feb 9, 2005, at 5:08 PM, John C Cartwright wrote:
>>>
>>>> Hi Steve,
>>>>
>>>> thanks for the prompt response and the suggestion.
>>>>
>>>> gdb is just telling me the error occurred in memory allocation, but
>>>> this
>>>> is not helping me much:
>>>>
>>>> (gdb) run
>>>> Starting program: /extra/contrib/apache/cgi-bin/mapserver-4.4.1
>>>> [Thread debugging using libthread_db enabled]
>>>> [New Thread -1218617216 (LWP 8708)]
>>>>
>>>> Program received signal SIGSEGV, Segmentation fault.
>>>> [Switching to Thread -1218617216 (LWP 8708)]
>>>> 0x039ba0d1 in realloc () from /lib/tls/libc.so.6
>>>>
>>>> I was hoping to tell what request parameter or map configuration
>>>> element
>>>> might be causing trouble. Can you think of any way for me to pursue
>>>> this
>>>> at a higher level?
>>>>
>>>> Thanks!
>>>>
>>>> -- john
>>>>
>>>>
>>>>
>>>> Stephen Woodbridge wrote:
>>>>
>>>>> John,
>>>>>
>>>>> You can run mapserver cgi at the command line, but you need to set up
>>>>> the environment variables first, like
>>>>>
>>>>> export REQUEST_METHOD=GET
>>>>> export QUERY_STRING="...."
>>>>> gdb mapserv
>>>>> run
>>>>>
>>>>> set your QUERY_STRING appropriately
>>>>>
>>>>> -Steve W.
>>>>
>>>>
>>>>
>>
>