[GRASS-user] v.generalize: does it take forever?

[Fábio Dias]

As promised, profile of v.generalize, as of r63952.
(The data might not be exactly the same, I might have run v.clean somewhere).

I still have the raw profiles, if anyone wants them.

F
-=--=-=-
Fábio Augusto Salve Dias
http://sites.google.com/site/fabiodias/


On Sun, Jan 4, 2015 at 6:01 PM, Fábio Dias <fabio.dias at gmail.com> wrote:
> Attached is pdf generated with google-perf of v.generalize, using
> g7b4. I'm running it again for trunk.
> -=--=-=-
> Fábio Augusto Salve Dias
> http://sites.google.com/site/fabiodias/
>
>
> On Sun, Jan 4, 2015 at 5:54 PM, Markus Metz
> <markus.metz.giswork at gmail.com> wrote:
>> On Wed, Dec 31, 2014 at 5:20 PM, Fábio Dias <fabio.dias at gmail.com> wrote:
>>>
>>> I fussed about the v.generalize code, thinking about pthread
>>> parallelization. The geometry part of the code is *really* fast and
>>> can be easily parallelized so it can run even faster. But, according
>>> to the profile google-perf gave me, the real bottleneck is inside the
>>> check_topo function (which uses static vars and inserts a new line
>>> into the vector, not only checks if it breaks topo - got stuck a while
>>> in there due to the misnomer). More specifically in the Rtree function
>>> used to check if one line intersects other lines.
>>>
>>
>> The function used in check_topo is Vect_line_intersection() which does
>> much more than just testing for intersections. The process could be
>> made much faster if Vect_line_check_intersection() would be modified
>> such that connections by end points are ignored. But I don't know if
>> this would break other modules or other functionality.
>>
>> Markus M
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