Logger instantiated for package org.apache.parquet may be GC-ed

[asfimport]

This ticket is derived from SPARK-8122.

According to Javadoc of java.util.Logger:

It is important to note that the Logger returned by one of the getLogger factory methods may be garbage collected at any time if a strong reference to the Logger is not kept.
However, the only reference to the Logger created for package org.apache.parquet goes out of scope outside the static initialization block, and thus is possible to be garbage collected.

More details can be found in this comment.

Reporter: Cheng Lian / @liancheng
Assignee: Ryan Blue / @rdblue

Related issues:

• Release Parquet-mr 1.9.0 (blocks)
• Deprecate Log and move to SLF4J Logger (relates to)
• Format: Do not shade slf4j-api (relates to)
• Remove ParquetLogRedirector usage from ParquetFileFormat (relates to)
• System.out is used as logger in org.apache.parquet.Log (is required by)

PRs and other links:

• PR #290

_{Note: This issue was originally created as PARQUET-305. Please see the migration documentation for further details.}

[asfimport]

Ryan Blue / @rdblue:
We've talked for a while about moving to SLF4J so I went ahead and implemented that as a fix for this problem. That should make redirecting logs easier in general.

We can always go with a simpler fix for the 1.9.0 release, but this seemed like a good excuse to get this done.

[asfimport]

Ryan Blue / @rdblue:
Merged #290