[tor-bugs] #16585 [Tor]: relay stops forwarding all traffic when client function cannot establish circuits -- scheduler_run() starvation

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#16585: relay stops forwarding all traffic when client function cannot establish
circuits -- scheduler_run() starvation
---------------------------+--------------------------------
     Reporter:  starlight  |      Owner:
         Type:  defect     |     Status:  new
     Priority:  major      |  Milestone:  Tor: 0.2.7.x-final
    Component:  Tor        |    Version:  Tor: 0.2.6.10
   Resolution:             |   Keywords:  PostFreeze027
Actual Points:             |  Parent ID:
       Points:             |
---------------------------+--------------------------------

Comment (by mikeperry):

 What there are more sources of this type of side-channel caused by other
 slow operations? Perhaps the actual channel send+recv handling is what
 should be done in a worker thread, rather than as a scheduled event?

 Related question: Would the transition to multithreaded crypto help this
 at all, or would that be mostly orthogonal?
 (https://trac.torproject.org/projects/tor/wiki/org/projects/Tor/MultithreadedCrypto).

 As a stopgap, maybe we can create cached data structures of the relay
 lists that allow for faster searching for a good relay in frequently-
 repeated cases?

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/16585#comment:14>
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