[tor-bugs] #19974 [Core Tor/Tor]: Test failure for monotonic time on slow machines

Tor Bug Tracker & Wiki blackhole at torproject.org
Sun Nov 13 00:11:04 UTC 2016


#19974: Test failure for monotonic time on slow machines
--------------------------+------------------------------------
 Reporter:  cypherpunks   |          Owner:  nickm
     Type:  defect        |         Status:  accepted
 Priority:  Medium        |      Milestone:  Tor: 0.2.9.x-final
Component:  Core Tor/Tor  |        Version:  Tor: 0.2.9.2-alpha
 Severity:  Normal        |     Resolution:
 Keywords:  regression    |  Actual Points:
Parent ID:                |         Points:  .1
 Reviewer:                |        Sponsor:
--------------------------+------------------------------------

Comment (by s7r):

 Are we sure it occurs as described on slow machines only? Because the
 machine under my control which experienced this isn't old and shouldn't be
 so slow at all.

 I have tried with Tor process off and absolutely nothing else running on
 the machine, got two times in a row:

 {{{
 util/monotonic_time:
   FAIL src/test/test_util.c:5536: assert(usecc1 OP_LE nsecc1 / 1000 + 10):
 10601698 vs 10601677
   [monotonic_time FAILED]
 }}}

 {{{
 util/monotonic_time:
   FAIL src/test/test_util.c:5536: assert(usecc1 OP_LE nsecc1 / 1000 + 10):
 7245695 vs 7245672
   [monotonic_time FAILED]
 }}}

 3rd time it reported OK without restarting the server or any process.
 After 3 minutes 4th time again fails:
 {{{
 util/monotonic_time:
   FAIL src/test/test_util.c:5534: assert(usec1 OP_LE nsec1 / 1000 +10):
 13577362 vs 13577356
   [monotonic_time FAILED]
 }}}

 {{{
 util/monotonic_time:
   FAIL src/test/test_util.c:5534: assert(usec1 OP_LE nsec1 / 1000 +10):
 7813125 vs 7813119
   [monotonic_time FAILED]
 }}}
 Before and after each failed test I've checked the date on the machine
 against a time server and it was synced exactly.

 I think we can eliminate the variant that the Tor process hangs, as
 described in
 https://trac.torproject.org/projects/tor/ticket/20423#comment:21 because
 as we see it happens even when Tor isn't actually running as a process on
 the server. Tried several times on another machine running Debian but got
 OK result every time.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/19974#comment:8>
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