[OSRM-talk] Route flapping / osrm-prepare adds randomness?

[Florian Lohoff]

On Wed, Jul 01, 2015 at 02:37:25PM +0200, Patrick Niklaus wrote:
> Confirmed on current develop branch using the Isle of Man extract.
> Currently bisecting to find out which change caused this. It is
> expected that pre-processing is not 100% deterministic, since we use
> parallel sorting (node IDs will change), so the JSON response will
> always have a different checksum. However the geometry should always
> be the same.
> 
> In theory it could happen that two paths with exactly the same travel
> time get chosen in different files (because of different node ids, so
> the edges are traversed in different order).

Even with the same travel time it'll be very much appreciated if there
was a deterministic ordering (which is the route and which the
alternate) - In the end by highest osm node id or street name or
whatever.

And it seems the order of the json result is also "random". I know
that its not specified what order an json dictionary/object gets
serialized but its interesting to see.

BTW: I have seen this kind of route flap before 0.3.9 IMHO probably even
before 0.3.4 - It just got more anoying as i process a lot more routes
so the noise went way up.

Flo
-- 
Florian Lohoff                                                 f at zz.de
     We need to self-defense - GnuPG/PGP enable your email today!
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