S3A Metrics in S3AInstrumentation Cause Memory Leaks in HBase Export

While using HBase S3A Export Snapshot utility we started to experience memory leaks of the process after version upgrade.

By running code analysis we traced the cause to revision 6555af81a26b0b72ec3bee7034e01f5bd84b1564 that added the following static reference (singleton):

private static MetricsSystem metricsSystem = null;

When application uses S3AFileSystem instance that is not closed immediately metrics are accumulated in this instance and memory grows without any limit.

Expectation:

• It would be nice to have an option to disable metrics completely as this is not needed for Export Snapshot utility.
• Usage of S3AFileSystem should not contain any static object that can grow indefinitely.