[tor-bugs] #31841 [Core Tor/Tor]: test addr/parse takes a long time on master on some machines

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#31841: test addr/parse takes a long time on master on some machines
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 Reporter:  teor                       |          Owner:  nickm
     Type:  defect                     |         Status:  accepted
 Priority:  High                       |      Milestone:  Tor:
                                       |  0.4.2.x-final
Component:  Core Tor/Tor               |        Version:  Tor: unspecified
 Severity:  Normal                     |     Resolution:
 Keywords:  tor-unit-tests 042-should  |  Actual Points:
Parent ID:                             |         Points:
 Reviewer:                             |        Sponsor:
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Comment (by nickm):

 I suspected systems with slow DNS.  Fortunately, all our blocking DNS
 lookup happens in one place, in one block within `tor_addr_lookup()`, so
 it's easy to see which unit tests call it.  They are:

  * `addr/parse` (over 180 times)
  * `config/parse_port_config__ports__ports_given` (twice)
  * `hs_config/valid_service_v2` (once)
  * `hs_config/valid_service_v3` (once)
  * `options/validate` (once)

 So if a system has a DNS resolver that is susceptible to timeouts, we
 would expect `addr/parse` to block, and nothing else.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/31841#comment:9>
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