[tor-bugs] #21394 [Core Tor/Tor]: connection timeouts are affecting Tor Browser usability

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#21394: connection timeouts are affecting Tor Browser usability
-------------------------------------------------+-------------------------
 Reporter:  arthuredelstein                      |          Owner:  (none)
     Type:  defect                               |         Status:
                                                 |  merge_ready
 Priority:  Very High                            |      Milestone:  Tor:
                                                 |  0.3.2.x-final
Component:  Core Tor/Tor                         |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  tbb-performance, tbb-usability,      |  Actual Points:
  performance, tbb-needs                         |
Parent ID:                                       |         Points:
 Reviewer:                                       |        Sponsor:
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Comment (by Dhalgren):

 Replying to [comment:42 Dhalgren]:
 > Allow me to assert  my original tuning recommendation is well considered
 and advisable:
 >
 > resolv.conf -- final recommendation
 > {{{
 > options timeout:5 attempts:1 max-inflight:16384 max-timeouts:1000000
 > nameserver 127.0.0.1
 > }}}

 A the time I came up with the above, my assumption was DNS timeouts are
 propagated back to clients, but I see per comment:8

 >>Makes sense. If the DNS resolve fails at an exit, does the exit send an
 error message back to the client? Or does it silently fail, meaning the
 client has to wait for the full 10-second timeout?
 >It depends on how it fails.
 >If the resolve times out at the exit, it also times out at the client,
 >If the resolve fails fast, a an error cell is sent to the client.

 that in this case nothing is sent and the client times-out at 10 seconds
 independently, therefore for Unbound-specific configurations it should be

 {{{
 options timeout:10 attempts:1 max-inflight:16384 max-timeouts:1000000
 nameserver 127.0.0.1
 }}}

 but concede that in the general case where the resolver is either named or
 Unbound, that

 {{{
 options timeout:5 attempts:2 . . .
 }}}

 is a better choice

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/21394#comment:53>
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