[YARN-9376] too many ContainerIdComparator instances are not necessary

• Type: Improvement
• Status: Patch Available
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 3.1.1, 3.1.2
• Component/s: resourcemanager
• Target Version/s: 3.1.4
• Assignee: lindongdong
• Reporter: lindongdong
• Created: 11/Mar/19 12:18
• Updated: 26/Aug/19 07:48

Description

 One RMNodeImpl will create a new ContainerIdComparator instance, but it is not necessary.

we may keep a static ContainerIdComparator instance and it is enough.

org.apache.hadoop.yarn.server.resourcemanager.rmnode.RMNodeImpl#containersToClean

/* set of containers that need to be cleaned */
private final Set<ContainerId> containersToClean = new TreeSet<ContainerId>(
    new ContainerIdComparator());