[tor-relays] Overloaded state indicator on relay-search

Georg Koppen gk at torproject.org
Tue Oct 19 07:14:33 UTC 2021


David Goulet:
> On 17 Oct (13:54:22), Arlen Yaroslav via tor-relays wrote:
>> Hi,
> 
> Hi Arlen!
> 
>>
>> I've done some further analysis on this. The reason my relay is being marked
>> as overloaded is because of DNS timeout errors. I had to dive into the
>> source code to figure this out.
>>
>> In dns.c, a libevent DNS_ERR_TIMEOUT is being recorded as an
>> OVERLOAD_GENERAL error. Am I correct in saying that a single DNS timeout
>> error within a 72-hour period will result in an overloaded state? If so, it
>> seems overly-stringent given that there are no options available to tune the
>> DNS timeout, max retry etc. parameters. Some lower-specced servers with less
>> than optimal access to DNS resolvers will suffer because of this.
> 
> Correct, 1 single DNS timeout will trigger the general overload flag. There
> were discussion to make it N% of all request to timeout before we would report
> it with a N being around 1% but unfortunately that was never implemented that
> way. And so, at the moment, 1 timeout is enough to trigger the problem.
> 
> And I think you are right, we would benefit on raising that threshold big
> time.

FWIW: that's tracked in

https://gitlab.torproject.org/tpo/core/tor/-/issues/40491

We had that on our radar previously but it fell through the cracks. :(

Georg

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