On Thu, 26 Jul 2012 17:11:17 +0200 Moritz Bartl <moritz@torservers.net> wrote:

We sometimes see "Your computer is too slow to handle this many circuit creation requests!" on our servers. Scott Bennett suggested to set MaxOnionsPending to 250 instead of the default of 100, which at least makes the warnings disappear. [1]

I am thinking about modifying out torrc template we use as as basis for all servers. What is the negative impact of setting MaxOnionsPending to 250? Should we instead reduce the bandwidth as suggested in the warning?

I don't think so. To the best of my recollection, I've only seen this message in recent versions of tor when it appeared that my node had been chosen for one or more high-volume hidden service operations, where the traffic volume in B/s was still fairly low, yet the number of connections had suddenly climbed to an unusually high level. The data throughput capacity vastly exceeded the actual traffic, but the onionskin-decoding load was sometimes, but probably not continually, very high until the hidden service(s) either shut down or changed their advertised information in the hidden service directory. To lower my node's RelayBandwidth* values would most likely have little impact on the bottleneck. Raising MaxOnionsPending adds a little slack in the queue to handle the occasions where that activity is temporarily backlogged prevents dropped connections and allows operations to proceed normally with only minimal extra delays. Consider a delay of probably no more than a second at the outside and usually less versus the delay of building a new circuit to a hidden service due to a dropped connection.

[1] https://lists.torproject.org/pipermail/tor-relays/2012-May/001352.html

Scott Bennett, Comm. ASMELG, CFIAG ********************************************************************** * Internet: bennett at cs.niu.edu * *--------------------------------------------------------------------* * "A well regulated and disciplined militia, is at all times a good * * objection to the introduction of that bane of all free governments * * -- a standing army." * * -- Gov. John Hancock, New York Journal, 28 January 1790 * **********************************************************************