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So, I started having "tubes clogged" problems this evening and realized, finally, that my Raspberry Pi powered relay had been weathering a circuit creation storm since about 18:11 my time.
tl;dr main dev-related questions at bottom
Aug 29 18:11:03.000 [warn] Your computer is too slow to handle this many circuit creation requests! Please consider using the MaxAdvertisedBandwidth config option or choosing a more restricted exit policy. Aug 29 18:12:02.000 [warn] Your computer is too slow to handle this many circuit creation requests! Please consider using the MaxAdvertisedBandwidth config option or choosing a more restricted exit policy. [2692 similar message(s) suppressed in last 60 seconds]
First off, I'm happy to note that the Pi is far, FAR more able to weather these storms running 0.2.4.x, even without the perfectly optimal OpenSSL (all jokes aside about that particular combination of three words)...
Secondly, the number of messages escalated. Here is the worst:
Aug 29 18:38:04.000 [warn] Your computer is too slow to handle this many circuit creation requests! Please consider using the MaxAdvertisedBandwidth config option or choosing a more restricted exit policy. [18258 similar message(s) suppressed in last 60 seconds]
What on earth is causing so many circuit creation requests in such a short timespan?
Again, a Pi-specific note - on 0.2.3.x, the Pi would have crashed or Tor been killed before this number ever reached five digits, so 0.2.4.x is better! I has a metric!
However, note that whatever is going on starts plugging up the works in Tor itself:
Aug 29 18:18:36.000 [notice] Tried for 129 seconds to get a connection to [scrubbed]:993. Giving up. (waiting for circuit) Aug 29 18:19:04.000 [warn] Your computer is too slow to handle this many circuit creation requests! Please consider using the MaxAdvertisedBandwidth config option or choosing a more restricted exit policy. [7190 similar message(s) suppressed in last 60 seconds] Aug 29 18:19:14.000 [notice] Your network connection speed appears to have changed. Resetting timeout to 60s after 18 timeouts and 172 buildtimes.
I assure you, my network connection speed didn't change. I still don't know how in the Tor protocol a circuit creation request is made, but maybe it was them gobbling bandwidth. Probably not, though? There was an increase in average TX/RX bandwidth during this incident, but not to levels that are in any way out of the ordinary for how I use my Internet connection.
However, it's still causing trouble with my router (which is running Tomato). Check this out:
Aug 29 18:56:14.000 [warn] Your computer is too slow to handle this many circuit creation requests! Please consider using the MaxAdvertisedBandwidth config option or choosing a more restricted exit policy. [13867 similar message(s) suppressed in last 60 seconds] Aug 29 18:56:40.000 [warn] eventdns: All nameservers have failed
[snipped similar "too slow to handle" messages]
Aug 29 19:05:19.000 [notice] eventdns: Nameserver 192.168.1.1:53 is back up
My main question: How do circuit creation requests on one's Tor relay cause load on one's network infrastructure? Is it DNS requests? Is it TCP connection state entries? It's not bandwidth, we observed that above, and my router can handle far faster pipes than the one it's on currently. The DNS failing is a sign that the router is under severe stress. Back in the 0.2.3.x days, I often had to reboot the *router* after one of these storms, not just the Tor relay.
And again - do we really know what is causing this? Something seems seriously wrong with the kind of numbers I'm seeing coming in to a node with MaxAdvertisedBandwidth 250KB.
I think a bug should be opened about this, if there isn't one already.
Regards, - -Gordon M.