[tor-bugs] #29743 [Core Tor/Tor]: Long-running tor instances fail to keep up-to-date directory information

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#29743: Long-running tor instances fail to keep up-to-date directory information
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     Reporter:  karsten       |      Owner:  (none)
         Type:  defect        |     Status:  new
     Priority:  Medium        |  Milestone:
    Component:  Core Tor/Tor  |    Version:  Tor: 0.3.0.7
     Severity:  Normal        |   Keywords:
Actual Points:                |  Parent ID:
       Points:                |   Reviewer:
      Sponsor:                |
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 We have a small number of long-running tor instances as part of our
 OnionPerf setups that are running 24/7. In the past, some of these tor
 instances got into a state where their directory information was no longer
 up-to-date enough to build circuits. In some cases they recovered after
 hours, days, or even weeks, but in some cases we had to restart the tor
 processes.

 I'm attaching a graph that shows the number of open circuits as reported
 in heartbeat log messages. That number is relatively stable most of the
 time, depending on whether we're using the tor instance for making
 requests or for providing an onion service. But in some cases the number
 drops to zero, which coincides with the log message:

 {{{
 [notice] Our directory information is no longer up-to-date enough to build
 circuits: [...]
 }}}

 The graph also shows that sometimes the number magically goes up again.
 Those times coincide with the following log message:

 {{{
 [notice] We now have enough directory information to build circuits.
 }}}

 The purple dashed lines show when we restarted tor processes manually.
 Some of these restarts are unrelated to the number of open circuits. But
 some restarts happened explicitly because the tor instance was not working
 anymore for our measurements.

 By the way, the op-nl instance shown in the middle was running
 0.2.9.11-dev, whereas the op-us and op-hk instances were running
 0.3.0.7-dev. It may be coincidence, but the older op-nl did not run out of
 up-to-date directory information, whereas the newer op-us and op-hk did.
 Was this issue maybe introduced in 0.3.0.x?

 I have tor logs available for all these tor instances. I can easily
 provide them, either as a big tarball or for specific days and instances
 as a smaller tarball. Just let me know.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/29743>
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