[tor-bugs] #28511 [Core Tor/Tor]: Limit the number of open testing circuits, and the total number of testing circuits

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#28511: Limit the number of open testing circuits, and the total number of testing
circuits
-------------------------------------------------+-------------------------
 Reporter:  teor                                 |          Owner:  (none)
     Type:  defect                               |         Status:  new
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  0.4.0.x-final
Component:  Core Tor/Tor                         |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  fast-fix, tor-bwauth, tor-dos,       |  Actual Points:
  035-backport, 034-backport, 033-backport,      |
  029-backport                                   |
Parent ID:  #22453                               |         Points:
 Reviewer:                                       |        Sponsor:
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Changes (by teor):

 * keywords:
     tor-bwauth, tor-dos, 035-backport, 034-backport-maybe, 033-backport-
     maybe, 029-backport-maybe-not
     =>
     fast-fix, tor-bwauth, tor-dos, 035-backport, 034-backport,
     033-backport, 029-backport


Comment:

 One fast fix is to test ORPorts and DirPorts every 20 seconds, rather than
 every 1 (ORPort) or 5 (DirPort) seconds.

 If a relay tries 60 internal circuits and 60 exit circuits, and all of
 them fail, it is almost certainly unreachable.

 A lower number of tests would probably lead to some small error rate. (But
 relays do retry the tests after every new consensus, so rare errors are
 acceptable.)

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/28511#comment:3>
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