[GRASS-dev] [GRASS GIS] #2185: Painfully Slow 'v.in.ogr' Vector Import

[GRASS GIS]

#2185: Painfully Slow 'v.in.ogr' Vector Import
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  Reporter:  justinzane  |      Owner:  grass-dev@…
      Type:  defect      |     Status:  new
  Priority:  normal      |  Milestone:  7.0.6
 Component:  Vector      |    Version:  svn-trunk
Resolution:              |   Keywords:  import, OGR, performance, v.in.ogr
       CPU:  x86-64      |   Platform:  Linux
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Comment (by mmetz):

 Replying to [comment:34 neteler]:
 > Wow. After full recompilation, with gcc it does  NOT "hang":
 [...]
 >
 > So, unfortunate clang compiler settings before or gcc-is-better-than-
 clang here?

 No, the difference is -O2 which you used with gcc but not with clang. I
 could reproduce the problem by not using any optimization.

 The problem is that Vect_break_lines() enters an infinite loop because it
 continuously generates two new lines that are again intersecting each
 other, always at the same locations.

 The attached patch ([comment:31 hcho]) helps, but as mentioned in
 comment:31 there are more comparisons and it does not seem to be a good
 idea to allow tolerance at some places but not at other places when
 comparing a cross with a vertex.

 What also helps is using Vect_line_intersection2() instead of
 Vect_line_intersection(). Interestingly, Vect_line_intersection2() does
 not need the patch, even though that part of the code is identical.

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Ticket URL: <https://trac.osgeo.org/grass/ticket/2185#comment:36>
GRASS GIS <https://grass.osgeo.org>