Prepared MultiPolygon predicates leak memory

[olt]

Using prepared binary predicates like 'contains' with MultiPolygons leaks memory. I have tested it with 3.1.1, 3.2.0 (using Shapely, which uses the C API) and latest trunk (r2982) with the attached C test program. So it might be a C API only bug.

The test program does not leak if the predicate is called directly with the MultiPolygon (no prepared geometry) or if the prepared geometry is only a polygon.

[olt]

Test program to demonstrate memory leak

[sgillies]

Leaks and valgrind both say no leaks, but the footprint of the prepared geometry does grow. Looks like it's accumulating data as contains() is called.

[strk]

3.2.2 fixed context leaks can you still see the leak with that version ?

[olt]

No. Just recompiled the test program and it still leaks memory.

% gcc memleak_mp_prep.c -o memleak_mp_prep -L../tmp/geos-3.2.2/capi/.libs/ -lgeos_c
% DYLD_LIBRARY_PATH=../tmp/geos-3.2.2/capi/.libs:../tmp/geos-3.2.2/source/.libs ./memleak_mp_prep

[olt]

Ok. I did some testing with a profiler and there are a lot of malloc calls from MCIndexSegmentSetMutualIntersector. Further testing shows that chainStore is growing infinite.

[strk]

I can confirm the analisys. Will look for a possible workaround. We have no garbage collector so must find out when it is safe to cleanup.

[strk]

Fixed in r3357. Thanks for not letting this issue fade away.

[olt]

Great. I tested it with trunk again and it looks like it was the only leak, since memory is now constant.