[tor-bugs] #28866 [Core Tor/sbws]: ResultDump.queue.put() can hang if the queue is full

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#28866: ResultDump.queue.put() can hang if the queue is full
---------------------------+-----------------------------------
 Reporter:  teor           |          Owner:  juga
     Type:  defect         |         Status:  needs_revision
 Priority:  Medium         |      Milestone:  sbws: 1.0.x-final
Component:  Core Tor/sbws  |        Version:  sbws: 1.0.2
 Severity:  Normal         |     Resolution:
 Keywords:                 |  Actual Points:
Parent ID:  #28663         |         Points:  1
 Reviewer:  mikeperry      |        Sponsor:
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Changes (by mikeperry):

 * status:  needs_review => needs_revision


Comment:

 Hrmm. I might need to look at a lot more of the sbws code, but I don't
 think the patch is the best way to do this. If the queue can also be added
 from another thread, then there still can be a race where it ends up full
 after the loop check but before the next statement. I would instead make
 it do something like:

 {{{
 while True:
   try:
     result_dump.queue.put(measurement_result, timeout=1)
   except Full as e:
     log.info('The results queue is full, after 1 second it should not be
 full')
 }}}

 That way, if the timeout hits because the queue is full for a second, the
 exception is thrown, and then you log, and then you try again for another
 second (at which point it should succeed, but in case it does not, you
 just log and try again rather than raise an uncaught Full exception).

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/28866#comment:7>
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