[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:
-------------------------------------------------+-------------------------

Comment (by Dhalgren):

 Replying to [comment:55 arma]:
 > Replying to [comment:54 arma]:
 > > the client starts its 10 second timer when it sends the begin cell
 >
 > I should also point out that the client's *first* stream attempt is 10
 seconds, but subsequent attempts (once it's given up on the first one and
 tried a new circuit) are 15 seconds each.

 Interesting, thank you for the detail.  The number of successful resolves
 arriving between 5 and 15 seconds is on the order of 0.45% and the
 difference between discarding them and forwarding them not severe enough
 to cause me regret over configuring this for 18 months.  Here is a recent
 set of Unbound statistics to illustrate.  The data seems unlikely to be of
 actionable use to adversaries and hopefully it's not improper to share
 publicly:

 {{{
 unbound: [:0] info: server stats for thread 0: 1748646 queries, 368913
 answers from cach
 unbound: [:0] info: server stats for thread 0: requestlist max 331 avg
 134.014 exceeded
 unbound: [:0] info: average recursion processing time 6.735093 sec
 unbound: [:0] info: histogram of recursion processing times
 unbound: [:0] info: [25%]=0.0130326 median[50%]=0.0450708 [75%]=0.127054
 unbound: [:0] info: lower(secs) upper(secs) recursions
 unbound: [:0] info:    0.000000    0.000001 39515
 unbound: [:0] info:    0.000032    0.000064 1
 unbound: [:0] info:    0.000128    0.000256 1
 unbound: [:0] info:    0.000256    0.000512 23408
 unbound: [:0] info:    0.000512    0.001024 64670
 unbound: [:0] info:    0.001024    0.002048 33392
 unbound: [:0] info:    0.002048    0.004096 19250
 unbound: [:0] info:    0.004096    0.008192 47427
 unbound: [:0] info:    0.008192    0.016384 198450
 unbound: [:0] info:    0.016384    0.032768 159053
 unbound: [:0] info:    0.032768    0.065536 278833
 unbound: [:0] info:    0.065536    0.131072 181936
 unbound: [:0] info:    0.131072    0.262144 207508
 unbound: [:0] info:    0.262144    0.524288 45953
 unbound: [:0] info:    0.524288    1.000000 14731
 unbound: [:0] info:    1.000000    2.000000 7530
 unbound: [:0] info:    2.000000    4.000000 8677
 unbound: [:0] info:    4.000000    8.000000 2740
 unbound: [:0] info:    8.000000   16.000000 3461
 unbound: [:0] info:   16.000000   32.000000 11938
 unbound: [:0] info:   32.000000   64.000000 13751
 unbound: [:0] info:   64.000000  128.000000 4671
 unbound: [:0] info:  128.000000  256.000000 3268
 unbound: [:0] info:  256.000000  512.000000 6127
 unbound: [:0] info:  512.000000 1024.000000 2086
 unbound: [:0] info: 1024.000000 2048.000000 626
 unbound: [:0] info: 2048.000000 4096.000000 480
 unbound: [:0] info: 4096.000000 8192.000000 200
 unbound: [:0] info: 8192.000000 16384.000000 20
 unbound: [:0] info: 16384.000000 32768.000000 6
 unbound: [:0] info: 32768.000000 65536.000000 1
 }}}

 Unbound displays impressive patience w/r/t completing queries.  Arrived at
 0.46 by taking the percent of successful resolves under 16 seconds.  Is
 0.36% relative to queries resolved in under 16 seconds plus resolves from
 cache.  2.47% of queries resolve in over 16 seconds, are lost.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/21394#comment:56>
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