[OSM-talk] Overpass Quotas
roland.olbricht at gmx.de
Mon Apr 27 20:27:31 UTC 2015
in the last weeks the server overpass-api.de has seen a flood of extra
requests. Unfortunately, most of these requests have been from a few
The standard pattern has been apparently a server that fires as much
requests as possible, often some or most of them syntactically correct,
but semantically nonsense. For example, from one IP adress was sent the
same query for objects with name "Lipkenskothen" every 5 seconds (It is
very unlikely that these few results change more often than once per
month, hence a frequency of once per day would be more than enough).
While I may block such extreme cases with "iptables" (i.e., the server
then appears unreachable from that IP), I would like to avoid manual
blocking as much as possible. Beside the quite hard challenge of being
unbiased in blocking decisions, it is also a lot of annoying work.
For that purpose I have changed the quota calculation. I will uphold the
basic rule that a client shall not send more than one request in
parallel from an IP. For the other details, I'm trying an A/B-strategy
for traffic management, hence they may change quite often at the moment.
If you encounter a serious service degradation, in particular sustaining
HTTP 429 responses, please contact me by mail such that I can adjust the
algorithm to make fewer or no false positives.
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