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

[Florian Lohoff]

Hi,

On Tue, Jun 30, 2015 at 12:45:42PM +0200, Florian Lohoff wrote:
> Hi,
> 
> i am doing QA based on calculating routes. For this i have a defined
> set of points (couple hundret) which i calc routes between. On length
> change i get a notification by email that the route has changed.
> 
> Now i see routes which regularly flap between 2 different geometries and
> lengths without the OSM data beeing changed so i started investigating.
> 
> The route flap happens irregular when osrm-prepare'ing the same
> germany.osm.pbf over an over. I see route flaps on same OSM data input.
> 
> What i typically do (pseudo code) every 30-60 Minutes:
> 
> while true; do
> 	update-germany-file-with-osmupdate
> 	osrm-extract -p car.lua germany.osm.pbf
> 	osrm-prepare -p car.lua germany.osrm
> 	restart-osrm-routed
> 
> 	calculate-routes-and-compare-lengths
> done

Okay - i am brute forcing it now with a smaller planet extract and
find disturbing results.

Thats the script i am running - i do not touch the input file 
inbetween.




#!/bin/bash

set -x

trap "kill ${ROUTED}" exit

while true; do

        [ ! -d run ] || rm -rf run

        mkdir run

        ln -s ../input/nordrhein-westfalen-latest.osm.pbf \
                run/input.pbf

        bin/osrm-extract \
                -p car.lua \
                run/input.pbf
                
        bin/osrm-prepare \
                -p car.lua \
                run/input.osrm
                
        bin/osrm-routed \
                -p 5444 \
                -i 127.0.0.1 \
                run/input.osrm &

        ROUTED=$!

        sleep 2

        fname=`date +%Y%m%d%H%M%S`
        wget -q -O - \
	        "http://localhost:5444/viaroute?loc=51.8919434301567,8.4548220634405&loc=51.8950384046146,8.46314334319787&instructions=true&compression=false" \
        	>output/json.${fname}

        perl -MData::Dumper -MJSON -e 'my $g=decode_json(<STDIN>); print Dumper $g->{route_geometry};' \
                <output/json.${fname} \
                >output/geom.${fname}
        
        sleep 1
        
        kill ${ROUTED}

        sleep 2
done


Thats the output files:

-rw-r--r-- 1 flo flo   1210 Jun 30 12:55 json.20150630125542
-rw-r--r-- 1 flo flo   1210 Jun 30 12:59 json.20150630125950
-rw-r--r-- 1 flo flo   2270 Jun 30 13:03 json.20150630130358
-rw-r--r-- 1 flo flo   1368 Jun 30 13:08 json.20150630130805
-rw-r--r-- 1 flo flo   1368 Jun 30 13:12 json.20150630131215
-rw-r--r-- 1 flo flo   1368 Jun 30 13:16 json.20150630131623
-rw-r--r-- 1 flo flo   2270 Jun 30 13:20 json.20150630132033
-rw-r--r-- 1 flo flo   1210 Jun 30 13:24 json.20150630132442
-rw-r--r-- 1 flo flo   1368 Jun 30 13:28 json.20150630132852
-rw-r--r-- 1 flo flo   1368 Jun 30 13:33 json.20150630133301

As one can see from the sizes - they differe HUGEly ... 

flo at osm:~/projects/route-flap/output$ for i in json*; do json_pp <$i | grep found_alternative; done
   "found_alternative" : false,
   "found_alternative" : false,
   "found_alternative" : true,
   "found_alternative" : false,
   "found_alternative" : false,
   "found_alternative" : false,
   "found_alternative" : true,
   "found_alternative" : false,
   "found_alternative" : false,
   "found_alternative" : false,

Although i use the SAME input file - with the SAME coordinates to query for an route
i get different results. 

Its a permutation of route A or route B and with or without alternatives
it seems.

Extracting only the geometry with this perl onelines:

perl -MData::Dumper -MJSON -e 'my $g=decode_json(<STDIN>); print Dumper $g->{route_geometry};'

returns significantly different geometries.

-rw-r--r-- 1 flo flo   1696 Jun 30 12:55 geom.20150630125542
-rw-r--r-- 1 flo flo   1696 Jun 30 12:59 geom.20150630125950
-rw-r--r-- 1 flo flo   1696 Jun 30 13:03 geom.20150630130358
-rw-r--r-- 1 flo flo   2345 Jun 30 13:08 geom.20150630130805
-rw-r--r-- 1 flo flo   2345 Jun 30 13:12 geom.20150630131215
-rw-r--r-- 1 flo flo   2345 Jun 30 13:16 geom.20150630131623
-rw-r--r-- 1 flo flo   1696 Jun 30 13:20 geom.20150630132033
-rw-r--r-- 1 flo flo   1696 Jun 30 13:24 geom.20150630132442
-rw-r--r-- 1 flo flo   2345 Jun 30 13:28 geom.20150630132852
-rw-r--r-- 1 flo flo   2345 Jun 30 13:33 geom.20150630133301
-rw-r--r-- 1 flo flo   1696 Jun 30 13:37 geom.20150630133714

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