[postgis-devel] [pgrouting] need help with std::bad_alloc issue

[Stephen Woodbridge]

On 6/13/2013 3:23 AM, Sandro Santilli wrote:
> On Wed, Jun 12, 2013 at 04:56:22PM -0400, Stephen Woodbridge wrote:
>> Interestingly, I just traced down another of these issues. I turns
>> out this one was another in the family of std::vector problems. I
>> resolved it by adding my_vector.reserve(my_size) to the code before
>> we tried to add anything to the vector using a vector.push_back(...)
>>
>> While it is probably good practice to do this, it is not require and
>> the code works fine in a standalone command line program. I'm not
>> very knowledgeable in C++ and how it deals with creating objects,
>> etc, but this feels a lot like a bug in the create extension
>> facility where it missing a step of calling the c++ library
>> initialization code when the shared library is loaded and that some
>> how my adding the call to reserve() method initializes what should
>> have gotten initialized before and does get initialized when I
>> re-connect to the database and the connection code makes sure all my
>> libraries are loaded and initialized. But this is just my wild guess
>> based on what I'm observing and I could be way off base.
>
> Reserving some memory might be just perturbating uninitialized memory
> enough to postpone the problem. These hard-to-track bugs are often due
> to using uninitialized memory. Valgrind may not know because the backend
> process still is the owner of the whole memory block, but doesn't
> consider it taken from your specific code. Building with --enable-cassert
> _might_ help with that (but I'm not sure).
>
> If you use GCC you may also try to export the env variable
> GLIBCXX_FORCE_NEW (for GCC 3.4+) to reduce caching in the STL.
>
> Your goal is to consistently reproduce the bug, not to further hide it,
> so the less you .reserve the better...

Hi strk,

Thank you for the advice and support. I'm traveling next week, but after 
I get back I will try your suggestions. I think it would be a good idea 
to see if I can make a trivial standalone case that demonstrates this 
issue, I don't have high hopes that I can succeed, but its worth a try. 
Anyway, I need to close out a few issues before a leave, so that needs 
to take priority.

Thanks,
   -Steve