[tor-bugs] #29744 [Core Tor/Tor]: Streams sometimes stall for up to 1 hour without making any progress

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#29744: Streams sometimes stall for up to 1 hour without making any progress
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 Reporter:  karsten                  |          Owner:  (none)
     Type:  defect                   |         Status:  new
 Priority:  Medium                   |      Milestone:  Tor: unspecified
Component:  Core Tor/Tor             |        Version:  Tor: 0.3.0.7
 Severity:  Normal                   |     Resolution:
 Keywords:  needs-insight usability  |  Actual Points:
Parent ID:                           |         Points:
 Reviewer:                           |        Sponsor:
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Comment (by karsten):

 I looked at the op-ab logs, created by tor version 0.3.5.7-dev, and tried
 to identify stalling runs. The data basis here is much smaller with only 2
 months of logs from 1 instance as compared to 3 months of logs from 3
 instances in my initial analysis above.

 I found at least one measurement where the download stalled for 18 seconds
 (ID 103995) and a few more measurements with shorter stalls. I'm attaching
 a new graph and the controller events for the graphed measurements.

 My current guess is that it's not an issue with the client but with one of
 the relays. And if it were "just" 18 seconds, it might even be acceptable
 for most use cases.

 But I believe that most of the application-level timeouts after one hour
 and some of the really slow downloads in my first analysis suffer from the
 very same issue. Maybe a scheduling issue or a matter of picking a
 scheduling algorithm that treats all streams more fairly?

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/29744#comment:5>
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