## What changes were proposed in this pull request?
We have a config `spark.sql.files.ignoreCorruptFiles` which can be used to ignore corrupt files when reading files in SQL. Currently the `ignoreCorruptFiles` config has two issues and can't work for Parquet:
1. We only ignore corrupt files in `FileScanRDD` . Actually, we begin to read those files as early as inferring data schema from the files. For corrupt files, we can't read the schema and fail the program. A related issue reported at http://apache-spark-developers-list.1001551.n3.nabble.com/Skip-Corrupted-Parquet-blocks-footer-tc20418.html
2. In `FileScanRDD`, we assume that we only begin to read the files when starting to consume the iterator. However, it is possibly the files are read before that. In this case, `ignoreCorruptFiles` config doesn't work too.
This patch targets Parquet datasource. If this direction is ok, we can address the same issue for other datasources like Orc.
Two main changes in this patch:
1. Replace `ParquetFileReader.readAllFootersInParallel` by implementing the logic to read footers in multi-threaded manner
We can't ignore corrupt files if we use `ParquetFileReader.readAllFootersInParallel`. So this patch implements the logic to do the similar thing in `readParquetFootersInParallel`.
2. In `FileScanRDD`, we need to ignore corrupt file too when we call `readFunction` to return iterator.
One thing to notice is:
We read schema from Parquet file's footer. The method to read footer `ParquetFileReader.readFooter` throws `RuntimeException`, instead of `IOException`, if it can't successfully read the footer. Please check out df9d8e4154/parquet-hadoop/src/main/java/org/apache/parquet/hadoop/ParquetFileReader.java (L470). So this patch catches `RuntimeException`. One concern is that it might also shadow other runtime exceptions other than reading corrupt files.
## How was this patch tested?
Jenkins tests.
Please review http://spark.apache.org/contributing.html before opening a pull request.
Author: Liang-Chi Hsieh <viirya@gmail.com>
Closes#16474 from viirya/fix-ignorecorrupted-parquet-files.
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