[tor-bugs] #25461 [Core Tor/Tor]: main event-loop spins consuming 100% of a CPU core at times

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#25461: main event-loop spins consuming 100% of a CPU core at times
-------------------------------------------------+-------------------------
 Reporter:  Dhalgren                             |          Owner:  dgoulet
     Type:  defect                               |         Status:
                                                 |  accepted
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  0.3.5.x-final
Component:  Core Tor/Tor                         |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  performance, 034-roadmap-subtask,    |  Actual Points:
  034-triage-20180328, 034-included-20180328     |
Parent ID:  #25500                               |         Points:
 Reviewer:                                       |        Sponsor:
-------------------------------------------------+-------------------------

Comment (by Dhalgren):

 seeing CPU saturation today with 0.3.4.1-alpha

 removed all `tc` police rules with no effect, so not the comment:5 theory

 TAP handshakes skyrocketed and perhaps it's all TAP handshake CPU
 consmption

 also nf_conntrack is dropping connections due to lack of table slots,
 which implies scanning activity

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/25461#comment:12>
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