Parquet-hadoop's client side logs are buffered / do not print until the job completes

Log statements from the InputFormat or anywhere else in the hadoop client / submitter seem to get buffered until the MR job completes, instead of printing as the job progresses.

**Reporter**: [Alex Levenson](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=alexlevenson) / @isnotinvain

_{**Note**: *This issue was originally created as [PARQUET-27](https://issues.apache.org/jira/browse/PARQUET-27). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

未指定文件或测试。首先跟踪正在运行的 MapReduce 作业期间来自 InputFormat 和 Hadoop 客户端或提交器的日志记录，然后比较这些消息何时变得可见。完成的标准是，客户端日志语句会随着作业的进展而打印，而不是仅在作业完成后才打印。

由索引模型根据 Issue 内容生成。