usageTicks and totalTicks should be volatile to ensure that different threads get the latest ticks

A DESCRIPTION OF THE PROBLEM :
The usageTicks and totalTicks properties in the com.sun.management.internal.OperatingSystemImpl.ContainerCpuTicks class are not volatile, so different threads may not be able to get the latest cpu load when they get the cpu load.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Hard to reproduce, but usageTicks and totalTicks should be volatile to ensure that different threads get the latest ticks.