[geos-devel] [GEOS] #343: After applying a buffer over a multiline the library starts growing in memory usage and hungs

[strk]

On Fri, May 14, 2010 at 11:35:45AM -0700, Martin Davis wrote:
> Ok, I tried the roads_broken geometry in JTS using the buffer-and-union 
> approach.  The result matches the one you posted, strk.
> 
> Time was 2.7 s.  So the two systems are pretty close.
> 
> It would be interesting if you tried the other geometry as well.

Done, but on another (older) machine:
 Intel(R) Pentium(R) 4 CPU 2.66GHz
 bogomips        : 5333.43

Input points: 11502
Input components: 5615
Output points: 417

$ time psql -c ' select st_npoints(st_union(st_buffer(geom, 0.005)))
from ( select (st_dump(g)).geom from bug ) as foo; '
 real    1m9.838s
 user    0m0.100s
 sys     0m0.028s

Memory is fine, CPU is pretty much fixed at 100%.

Interesting enough the buffer itself is pretty quick:

$ time psql -c ' select sum(st_npoints(st_buffer(geom, 0.005)))
from ( select (st_dump(g)).geom from bug ) as foo;'
 real    0m3.170s
 user    0m0.108s
 sys     0m0.024s

--strk;

  ()   Free GIS & Flash consultant/developer
  /\   http://strk.keybit.net/services.html