[tor-bugs] #13823 [Chutney]: chutney intervals are too short for successful bootstrap, particularly under high CPU load on OS X

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#13823: chutney intervals are too short for successful bootstrap, particularly
under high CPU load on OS X
-------------------------+--------------------
     Reporter:  teor     |      Owner:  nickm
         Type:  defect   |     Status:  new
     Priority:  normal   |  Milestone:
    Component:  Chutney  |    Version:
   Resolution:           |   Keywords:  lorax
Actual Points:           |  Parent ID:  #13718
       Points:           |
-------------------------+--------------------

Comment (by teor):

 Trying to run two consensuses in as short as period as possible is fraught
 with restrictions.

 When trying to use the smallest allowable voting interval for testing, I
 have found the following restrictions for the new macro
 `MIN_VOTE_INTERVAL_TESTING`:
  * a minimum of `(MIN_VOTE_SECONDS + MIN_DIST_SECONDS) * 2 + 1 = 9` based
 on `V3AuthVoteDelay + V3AuthDistDelay [<] V3AuthVotingInterval/2`
 "V3AuthVoteDelay plus V3AuthDistDelay must be less than half
 V3AuthVotingInterval" in options_validate()
  * a minimum of 16 based on `min_sec_before_caching = interval/16` "slop
 factor in case clocks get desynchronized a little" in
 update_consensus_networkstatus_fetch_time_impl()
  * a minimum of 18 based on `(30*60) % TestingV3AuthInitialVotingInterval
 != 0` "[must] divide evenly into 30 minutes" in options_validate()
  * we may be able to get away with 9, 10, 12, 15 (which all divide 30
 minutes) if we allow min_sec_before_caching's "slop factor" to equal 0,
 which should be fine if we're running on the same host/clock

 So I have set:
 {{{
 #define MIN_VOTE_INTERVAL_TESTING 9
 }}}

 But set the vote interval to 18 in the chutney templates to play it a
 little less unsafe.
 (Other options are 20, 24, 25, 30, 36, 40, 45, 50, 60, ...)

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/13823#comment:5>
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