[MESOS-3552] CHECK failure due to floating point precision on reservation request

• Type: Task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.26.0
• Component/s: master
• Labels: mesosphere tech-debt
• Target Version/s: 0.26.0
• Flags: Important
• Epic Link: FloatPoint Operations
• Sprint: Mesosphere Sprint 28
• Story Points: 3
• Assignee: Mandeep Chadha
• Reporter: Mandeep Chadha
• Shepherd: Bernd Mathiske
• Due: 12/Oct/15
• Created: 29/Sep/15 21:17
• Updated: 26/Nov/18 12:22
• Resolved: 26/Nov/18 12:22

Description

result.cpus() == cpus() check is failing due to ( double == double ) comparison problem.

Root Cause :

Framework requested 0.1 cpu reservation for the first task. So far so good. Next Reserve operation — lead to double operations resulting in following double values :

results.cpus() : 23.9999999999999964472863211995 cpus() : 24

And the check ( result.cpus() == cpus() ) failed.

The double arithmetic operations caused results.cpus() value to be : 23.9999999999999964472863211995 and hence ( 23.9999999999999964472863211995 == 24 ) failed.

Issue Links

• is duplicated by: MESOS-3090 Calculated CPU should be rounded
• is duplicated by: MESOS-3518 Assertions that compare doubles with == can fail due to rounding issues and can crash the master.
• is duplicated by: MESOS-3990 Unexpected reservation results due to floating point error
• is related to: MESOS-3997 Switch to fixed-point for resources
• relates to: MESOS-1187 precision errors with allocation calculations