[OSM-dev] tile log dates

Martin Raifer tyr.asd at gmail.com
Fri Aug 26 12:14:03 UTC 2016


Thanks for looking into this, Tom!

But, I still have doubts that this fully explains the amount of
tile-accesses reported for the earthquake region in the
tiles-2016-08-23.txt.xz file: If I understand you correctly, this file
will contain access data for the time between approximately
2016-08-23T04:00:00Z and 2016-08-24T04:00:00Z, right? That means that
only the tile accesses during the first ~2.5 hours right after the
earthquake should be included (note that this is also right in the
middle of the night in central Europe when most interested people
would have still been sleeping; and also very few media would have
covered the earthquake and its full impact that quickly).

Still, the 2016-08-23 file reports quite too (?) many tile accesses
for this short time period: There are roughly half as many tiles
accesses reported in the earthquake region when compared to the log
file of the next day (2016-08-24). For example, in an arbitrarily
chosen bbox over the affected region, at zoom 15:

total tile accesses:
2016-08-23: 165,262
2016-08-24: 350,527

average tile accesses:
2016-08-23: 375
2016-08-24: 762

accesses of most popular tile:
2016-08-23: 3,968
2016-08-24: 7,202

On Fri, Aug 26, 2016 at 11:41 AM, Tom Hughes <tom at compton.nu> wrote:
> On 26/08/16 08:56, Martin Raifer wrote:
>
>> As you can clearly see, the dates mentioned in the logs' file names
>> don't match up with the actual event.
>>
>> Could it be that the dates are off by one? Or is something else going on?
>
>
> As is pretty much complete normal the log files don't roll over at exactly
> midnight - if for no other reason than that it would be very hard for the
> log rotation process to do everything instantly.
>
> Rather the cron job that rolls logs over normally runs at about four in the
> morning or so and we then save the old file under the previous days date, so
> you will see some messages whose date doesn't match the name.
>
> Tom
>
> --
> Tom Hughes (tom at compton.nu)
> http://compton.nu/



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