Marcelo Vanzin reassigned SPARK-23977:

    Assignee: Steve Loughran

> Add commit protocol binding to Hadoop 3.1 PathOutputCommitter mechanism
> -----------------------------------------------------------------------
>                 Key: SPARK-23977
>                 URL: https://issues.apache.org/jira/browse/SPARK-23977
>             Project: Spark
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 2.4.0
>            Reporter: Steve Loughran
>            Assignee: Steve Loughran
>            Priority: Minor
> Hadoop 3.1 adds a mechanism for job-specific and store-specific committers 
> (MAPREDUCE-6823, MAPREDUCE-6956), and one key implementation, S3A committers, 
> HADOOP-13786
> These committers deliver high-performance output of MR and spark jobs to S3, 
> and offer the key semantics which Spark depends on: no visible output until 
> job commit, a failure of a task at an stage, including partway through task 
> commit, can be handled by executing and committing another task attempt. 
> In contrast, the FileOutputFormat commit algorithms on S3 have issues:
> * Awful performance because files are copied by rename
> * FileOutputFormat v1: weak task commit failure recovery semantics as the 
> (v1) expectation: "directory renames are atomic" doesn't hold.
> * S3 metadata eventual consistency can cause rename to miss files or fail 
> entirely (SPARK-15849)
> Note also that FileOutputFormat "v2" commit algorithm doesn't offer any of 
> the commit semantics w.r.t observability of or recovery from task commit 
> failure, on any filesystem.
> The S3A committers address these by way of uploading all data to the 
> destination through multipart uploads, uploads which are only completed in 
> job commit.
> The new {{PathOutputCommitter}} factory mechanism allows applications to work 
> with the S3A committers and any other, by adding a plugin mechanism into the 
> MRv2 FileOutputFormat class, where it job config and filesystem configuration 
> options can dynamically choose the output committer.
> Spark can use these with some binding classes to 
> # Add a subclass of {{HadoopMapReduceCommitProtocol}} which uses the MRv2 
> classes and {{PathOutputCommitterFactory}} to create the committers.
> # Add a {{BindingParquetOutputCommitter extends ParquetOutputCommitter}}
> to wire up Parquet output even when code requires the committer to be a 
> subclass of {{ParquetOutputCommitter}}
> This patch builds on SPARK-23807 for setting up the dependencies.

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