Just a little follow-up posting on the latest findings (thanks to user
poltroon!) on the topic of this thread.

We recently discovered that a lot of our traffic and the -vast- majority
of the web requests were caused by some LMS instances sending an insane
amount of requests. Some single systems hit our servers with more than
2Mio. hits within 24h. Some "only" did like 20 requests per second for a
few hours. So I decided to implement hit rate limiting on the
load-balancers, rejecting the worst offenders. 

'User poltroon discovered those 503 errors in his server.log file'
(http://forums.slimdevices.com/showthread.php?t=105608). He was kind
enough to investigate the issue on his end. What he figured out was that
the hammering was caused by two instances of squeezelite running on the
same machine, configured to report the same MAC address. This somehow
triggered the query loop in LMS. Once he shut down one instance things
went back to normal.

So I went back to the log files and database. And sure enough: all of
the top offenders (those sending several 100k requests per day) are
using software players. Many of them no real Squeezebox at all.

Now I'm not saying using SW players is evil. BUT they're much more prone
to issues, as we have less control over them. And as a consequence of
this higher error rate we do see above-average cost for systems which
don't pay for the service...

Just one number: database queries per second instantly dropped by about
40-50% after I enabled the hit rate limiting. Those probably two to
three dozen installations running a broken configuration caused us to
install additional database servers in the past. And that costs real
money.

This random sample shows another issue:

20486

(if you recognize your setup, please check your configuration: it
triggered about 720k requests yesterday :-))

I doubt this user has three players in the kitchen (Kueche) and two in
the living room (Wohnzimmer). These are simply multiple setups which
were used over time. Software players are cheap. You install and remove
them whenever you feel like it. Alas, the data stays in the database and
must be processed whenever LMS requests the players list. And there are
users with hundreds of players. Two of those requests hammering us are
player status and pref sync queries. With an average of 50 prefs per
player stored in the database you can imagine that having a request sent
20x per second for every single player can hit us hard.

Ok, back to work. And please check your configurations. Thanks!


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Michael

http://www.herger.net/slim-plugins - MusicArtistInfo, MusicInfoSCR,
Smart Mix
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mherger's Profile: http://forums.slimdevices.com/member.php?userid=50
View this thread: http://forums.slimdevices.com/showthread.php?t=105461

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