[postgis-devel] Re: [postgis-users] Performance and memory problems

strk strk at keybit.net
Tue Dec 9 04:10:57 PST 2003


My suggestion was wrong, the output is corrupted anyway. 
Dave is looking at the POSTGIS->GEOS converter which might contain a bug.

Note that this seems to be a wild pointer bug, which means you can't
tell how long will it take to fix it :).

>From the C++ FAQ:

<< Wild pointers are the SCUD missiles of the software world - they
   are undetected terrorist instruments that wreak havoc in chaotic
   ways. >>

<< We call this voodoo debugging, since it is about as effective
   as a fortune teller reading chicken entrails - indeed, the 
   technology of reading entrails is remarkably similar to that of
   reading a core dump after corruption by wild pointers. >>

... happy hacking ... ;)

--strk;

   
andrea.aime wrote:
> As strk suggested, removing the pfree(r) line makes the overlay go on
> but the whole thing goes out of memory after reaching the 12000th
> result geometry (and consider that the baby has 21000 shared buffers,
> which is almost 160MB of shared memory. So, it seems that sometimes
> the above line incurs in a double free problem, but maybe the out
> of memory I get is due to non freed memory during the overlay ...
> 
> Best regards
> Andrea Aime
> 
> 
> 
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