[jira] [Created] (AURORA-1943) PreemptionVictimFilter does not handle varied ResourceTypes

["Bill Farner (JIRA)" <ji...@apache.org>]

Bill Farner created AURORA-1943:
-----------------------------------

             Summary: PreemptionVictimFilter does not handle varied ResourceTypes
                 Key: AURORA-1943
                 URL: https://issues.apache.org/jira/browse/AURORA-1943
             Project: Aurora
          Issue Type: Bug
          Components: Scheduler
            Reporter: Bill Farner
            Assignee: Bill Farner


Reported by Mauricio Garavaglia on the dev list:
{quote}
Hi guys,

There seems to be a bug in this comparator in PreemptionVictimFilter (
https://github.com/apache/aurora/blob/master/src/main/java/org/apache/aurora/scheduler/preemptor/PreemptionVictimFilter.java#L142)
because the comparator doesn’t satisfy transitivity, which is required by
Array.sort's Tim Sort implementation. This fails with a
"java.lang.IllegalArgumentException: Comparison method violates its general
contract!" from time to time.

For example this input of A, B, and C doesn't work in the current
comparator.

A: <1, 1, 1>
B: <2, 2, 2>
C: <0, 2, 1>

Based on the comparator:

B > A
B == C
C == A

Constructs impossible situation where C == B > A == C. As a workaround we
patched to simply sort based on RAM, but anyone have any suggestions about
what a permanent fix for upstream should be? Thanks
{quote}

A likely culprit is that the filter does not handle comparison of tasks containing different ResourceTypes.



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