PARQUET-2354: Fix race condition in CharsetValidator

[findepi]

The CharsetValidator has a static singleton instance at BinaryTruncator.DEFAULT_UTF8_TRUNCATOR.validator, so it can be accessed from multiple threads. Before the change, all threads would operate on a shared "dummy buffer" for decoding.

Jira

• My PR addresses the following Parquet Jira issues and references them in the PR title.
  • https://issues.apache.org/jira/browse/PARQUET-2354
  • In case you are adding a dependency, check if the license complies with the ASF 3rd Party License Policy.

Tests

• My PR adds the following unit tests OR does not need testing for this extremely good reason: addresses concurrency issue

Commits

• My commits all reference Jira issues in their subject lines. In addition, my commits follow the guidelines from "How to write a good git commit message":
  1. Subject is separated from body by a blank line
  2. Subject is limited to 50 characters (not including Jira issue reference)
  3. Subject does not end with a period
  4. Subject uses the imperative mood ("add", not "adding")
  5. Body wraps at 72 characters
  6. Body explains "what" and "why", not "how"

Documentation

• In case of new functionality, my PR adds documentation that describes how to use it.
  • All the public functions and the classes in the PR contain Javadoc that explain what it does

[findepi]

cc @raunaqmorarka

[Fokko]

Great catch @findepi

[findepi]

Thank you @wgtmac @Fokko for your review!

BTW i failed to run the failing test locally because brew installs too new thrift version. Can one of you please help me understand what do i need to do to fix it?

[Fokko]

So with Thrift they bumped the minimal version of Java to 11, so Parquet was unable to upgrade since we still support Java 8. With Thrift 0.19 they backported Java 8 support on my request, let me fix #1138 and then you should be able to test locally.

[findepi]

@Fokko thank you for explaining the thrift problem!

@wgtmac thank you for the merge!