[HADOOP-14953] MetricsSystemImpl should consistently check minicluster mode

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Component/s: test
• Target Version/s: 3.5.0
• Assignee: Bharat Viswanadham
• Reporter: Xiao Chen
• Created: 16/Oct/17 19:14
• Updated: 04/Jan/24 11:28

Description

Found this when writing some tests related to JvmMetrics.
It appears JvmMetrics.initSingleton twice in minicluster works, but JvmMetrics.create twice doesn't.

This jira suggests to investigate whether this is intentional, and likely make the check of DefaultMetricsSystem.inMiniClusterMode() consistent in MetricsSystemImpl to ease testing.

org.apache.hadoop.metrics2.MetricsException: Metrics source JvmMetrics already exists!
        at org.apache.hadoop.metrics2.lib.DefaultMetricsSystem.newSourceName(DefaultMetricsSystem.java:152)
        at org.apache.hadoop.metrics2.lib.DefaultMetricsSystem.sourceName(DefaultMetricsSystem.java:125)
        at org.apache.hadoop.metrics2.impl.MetricsSystemImpl.register(MetricsSystemImpl.java:229)
        at org.apache.hadoop.metrics2.source.JvmMetrics.create(JvmMetrics.java:95)