Routing errors in London

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Re: Routing errors in London

Postby Twister-UK » Sun Sep 08, 2013 1:54 pm

Unless you'd prefer a different route, then for consistency and comparison I'll start logging again tonight using the same start/end points as the previous tests.

Will 24 hours of data be sufficient or would you like it to run for longer? And do you need the raw data or just the csv summary?
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Re: Routing errors in London

Postby Twister-UK » Wed Aug 14, 2013 9:34 pm

Requesting just a single route doesn't seem to make the slightest difference...

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This plot starts at 14:00 on the 12th, and runs through until 20:25 today. The x axis ticks are every hour, and the y axis is response time in milliseconds as before. Clearly, the poor routing server is so badly overworked and/or underpowered that, even asking for just a single route, it follows the now quite familiar pattern of cycling between periods of returning incomplete routes to periods where no routes are returned at all, only resuming normal operation during the late evening-overnight-early morning quiet time (for the UK and western Europe timezones at least - does this mean there are different routing servers allocated to world.waze.com users depending on whereabouts in the world they are?).

Endpoint plot is also familiar...

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Raw data captured during this test: http://chizzum.com/lmr/test2.zip
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Re: Routing errors in London

Postby Twister-UK » Mon Aug 12, 2013 12:37 pm

Test has now been restarted with the client requesting just a single route each time...
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Re: Routing errors in London

Postby Twister-UK » Mon Aug 12, 2013 9:55 am

First bit of data from the new routing tester...

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Using our trusty old test route once again, this plot shows the server response time (in milliseconds) to each routing request (grey line) with the usual yellow and red background areas denoting requests where the returned route was incomplete or non-existent. The black line is a 5-point averaging of the raw response times. The plot starts at 00:00 today and runs through to around 10:15.

What's interesting here is that throughout the period where no routes were returned, there's a corresponding drop in average response times, which suggests the server is simply rejecting the requests as they arrive rather than attempting to calculate any routes and then timing-out during the process (the request timeout parameter was set to the default 60000 for this test). Bear in mind that the response times recorded by the test client include network transit times for both the request and response packets, in addition to the processing time of the routing server itself, so the odd spike in raw response times may be down to network congestion rather than server slowdown.

Raw data captured during this test: http://chizzum.com/lmr/test1.zip
Last edited by Twister-UK on Mon Sep 02, 2013 9:06 pm, edited 1 time in total.
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Re: Routing errors in London

Postby Twister-UK » Sun Aug 11, 2013 11:20 am

I've just rewritten the routing tester in Delphi, which makes it easier to extract the data of interest as well as providing additional data not available to the scripted version and allowing the request parameters to be modified, so expect some more results to be provided over the next few days...
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Re: Routing errors in London

Postby Twister-UK » Fri Aug 09, 2013 10:05 pm

Just noticed that in the request sent from livemap to the routing server, there's a timeout parameter which is set to 60000 (I'm assuming milliseconds). If I generate a modified request with a much shorter timeout parameter (<100) then I get an error response instead of the expected route. Given how long it can take the server to return results during the day, I wonder if the complete failures logged during my earlier testing were requests that timed-out before any routing results could be generated...
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Re: Routing errors in London

Postby Twister-UK » Wed Jul 31, 2013 10:34 pm

Last testing session ran into some Firefox hassles, preventing the full log from being saved. I did still get a complete 24 hour cycle, but this one runs from 16:00 on Monday to 16:00 on Tuesday, as opposed to the 00:00-00:00 logs of previous tests...

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"Quickest" results - pretty much business as usual here...


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"Shortest" results - business unusual here though, for the first time the routing engine has started returning incomplete routes here too... Notice though how the incomplete routes are all longer, significantly so, than the complete ones - I wonder if there were some temporary road closures that morning, or could this have coincided with a mapping update?


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Endpoint plot - red for quickest routes, blue for shortest and purple for where both types of route had the same endpoint. The black-ringed purple dot lower-left is the true endpoint.
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Re: Routing errors in London

Postby Twister-UK » Mon Jul 29, 2013 3:05 pm

dknight212 wrote:I've got an idea how it's done but am still amazed at the skill of some in the UK Waze community. Does anyone have any concerns that Waze HQ won't like calling the routing server so frequently?


You can thank Timbones, it's his Livemap navigation script I used as the basis for this one... And quite frankly, if Waze are concerned about one extra routing request per minute, then we've got more to worry about than the number of incomplete routes being returned.

I've now tweaked the script again to capture a bit of extra data based on some thoughts I had regarding the last set of results and why the fastest route might be falling short/failing entirely. Let's see what the next 24 hours brings us results-wise.
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Re: Routing errors in London

Postby Twister-UK » Sat Jul 27, 2013 12:06 am

And a plot of all the endpoints...

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Lots of similarities with the endpoint positions from the first test
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Re: Routing errors in London

Postby Twister-UK » Fri Jul 26, 2013 11:40 pm

Full 24-hour results have now been processed...

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As expected, beyond 20:00 nothing of interest occurred, with Livemap returning complete routes each time.

Of the 1440 routing requests placed, 554 resulted in incomplete routes and 214 resulted in no routes.
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