[tor-bugs] #21073 [- Select a component]: "PredictedPortsRelevanceTime 0" causes stagnant/uncommunicative onion services, stale descriptors

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#21073: "PredictedPortsRelevanceTime 0" causes stagnant/uncommunicative onion
services, stale descriptors
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     Reporter:  alecmuffett           |      Owner:
         Type:  defect                |     Status:  new
     Priority:  Medium                |  Milestone:
    Component:  - Select a component  |    Version:  Tor: 0.2.9.7-rc
     Severity:  Normal                |   Keywords:
Actual Points:                        |  Parent ID:
       Points:                        |   Reviewer:
      Sponsor:                        |
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 I am running 72 tor daemons with the following spec:

 Tor 0.2.9.7-rc (git-6b6ad81c2e140d85) running on Linux with Libevent
 2.0.21-stable, OpenSSL 1.0.1t and Zlib 1.2.8.

 ...on a cluster of identical Raspberry Pi hardware.

 The goal is to experiment with Tor bandwidth via OnionBalance, so I have
 been tweaking configurations because a cluster of N tor daemons doesn't
 really benefit from predictive persistent anything.

 The configuration (text in the footer) in about 8% of cases, creates a
 daemon which, after initial upload, appears to never (or-only-very-rarely
 - unsure) refresh its descriptors in an HSDir.

 This behaviour stops when "PredictedPortsRelevanceTime 0" is commented
 out.

 Using a small custom Stem script, I query the age of the 72 daemons'
 descriptor; the vast majority are less than 2 hours old, but some - the
 afflicted daemons - are 10+hours old.

 Sample output from my tool:

 {{{
 19:25:22 mistral:~ $ ls-hsdir `cat Dropbox/all-onions.txt`
 v=2 age=5183 pub(2016-12-23 18:00:00) 2pnhm32wvh2g6bod
 v=2 age=5183 pub(2016-12-23 18:00:00) 2ss5hl24km3cnedb
 # unavailable 44kpqx3wj4pdj4x3
 v=2 age=1583 pub(2016-12-23 19:00:00) 457vhfiipyfahsw2
 v=2 age=5183 pub(2016-12-23 18:00:00) 4byeybc6yyqvxc64
 v=2 age=12383 pub(2016-12-23 16:00:00) 4sj56yfqt6iimah2
 v=2 age=5183 pub(2016-12-23 18:00:00) 57j6n5nsrvl2n3lm
 # unavailable 5imawjwdy2332sk2
 v=2 age=5183 pub(2016-12-23 18:00:00) 5k2ukr3gjxw4iuwo
 v=2 age=12383 pub(2016-12-23 16:00:00) 6bdgdiyoqdaq65oh
 v=2 age=1583 pub(2016-12-23 19:00:00) 6egxpvvszfzriamo
 v=2 age=5183 pub(2016-12-23 18:00:00) 7rydmwifplyugjzg
 v=2 age=5183 pub(2016-12-23 18:00:00) a7ls3tboibdtexpa
 v=2 age=66383 pub(2016-12-23 01:00:00) apk2wb3qdwzovtdj
 v=2 age=1583 pub(2016-12-23 19:00:00) av6plyhrd5j7enoo
 v=2 age=1583 pub(2016-12-23 19:00:00) awocgbvyljq4nf2p
 v=2 age=5183 pub(2016-12-23 18:00:00) ayzn2s76oh4eqw45
 v=2 age=37583 pub(2016-12-23 09:00:00) b6rzknxn664juice
 # unavailable bnuy3zlmrnvljylh
 v=2 age=1583 pub(2016-12-23 19:00:00) btxtnep4ipsgiq6j
 ...
 ...
 }}}

 The daemons, despite some having such old descriptors, are all still
 reachable some 21 hours after launch

 I shall be taking these (cited) daemons down, but can recreate them pretty
 easily.

 Purely speculatively, it does sound vaguely similar to this Ricochet issue
 which arma reported to Ricochet: https://github.com/ricochet-
 im/ricochet/issues/245

 I have 2x 'debug' logs from the same physical machine, one which is of a
 'good' daemon and the other 'stale' daemon, running concurrently. The
 'good' log is 35Mb versus the 'stale' 27Mb, but comparison with other logs
 does not suggest a strong correlation for stale daemons vs: logfile size.

 The files are presumably too large to attach?  Even after compression they
 will be several Mb.

 Running carml on an stale daemon for HS_DESC activity showed little of
 note.  Surprisingly little, even.

 I'm stuck for ideas, but am aware that a very large site uses this option
 in its 2.7 config, so it would be good to know if it is needed and/or
 helpful for SingleOnions in 2.9, and.or also bugfixed.

 {{{
 19:28:24 rig2:hs2.d $ more config
 DataDirectory /home/alecm/master/halfagig/hs2.d
 HiddenServiceDir /home/alecm/master/halfagig/hs2.d
 ControlPort unix:/home/alecm/master/halfagig/hs2.d/control.sock
 SocksPort 0
 Log debug file /home/alecm/master/halfagig/hs2.d/log.txt
 SafeLogging 0
 HeartbeatPeriod 60 minutes
 # HiddenServicePort 19 localhost:8502
 # HiddenServicePort 22 localhost:22
 HiddenServicePort 80 localhost:10502
 HiddenServiceNumIntroductionPoints 3
 LongLivedPorts 19,22,80
 #
 # CircuitBuildTimeout 60
 # LearnCircuitBuildTimeout 0
 PredictedPortsRelevanceTime 0
 # UseEntryGuards 0
 # UseEntryGuardsAsDirGuards 0
 }}}

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/21073>
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