cloud-fan commented on a change in pull request #33002:
URL: https://github.com/apache/spark/pull/33002#discussion_r655508695
##########
File path:
core/src/main/scala/org/apache/spark/internal/io/HadoopMapReduceCommitProtocol.scala
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@@ -152,12 +153,21 @@ class HadoopMapReduceCommitProtocol(
tmpOutputPath
}
- protected def getFilename(taskContext: TaskAttemptContext, ext: String):
String = {
- // The file name looks like
part-00000-2dd664f9-d2c4-4ffe-878f-c6c70c1fb0cb_00003-c000.parquet
- // Note that %05d does not truncate the split number, so if we have more
than 100000 tasks,
+ protected def getFilename(ext: String): String = {
+ // Use the Spark task attempt ID which is unique within the write job, so
that file writes never
+ // collide if the file name also includes job ID. The Hadoop task id is
equivalent to Spark's
+ // partitionId, which is not unique within the write job, for cases like
task retry or
+ // speculative tasks.
+ // NOTE: this is not necessary for certain Hadoop output committers, as
they will create a
+ // unique staging directory for each task attempt, so we don't need to
worry about file name
+ // collision between different task attempts, and using Hadoop task
ID/Spark partition ID is
+ // also fine. For extra safety and consistency with the streaming side, we
always use the
+ // Spark task attempt ID here.
+ val taskId = TaskContext.get.taskAttemptId()
+ // The file name looks like
part-00000-2dd664f9-d2c4-4ffe-878f-c6c70c1fb0cb_00003.gz.parquet
+ // Note that %05d does not truncate the taskId, so if we have more than
100000 tasks,
// the file name is fine and won't overflow.
- val split = taskContext.getTaskAttemptID.getTaskID.getId
- f"part-$split%05d-$jobId$ext"
+ f"part-$taskId%05d-$jobId$ext"
Review comment:
A more aggressive way is to simply use a fresh UUID here, but I'm not
sure if that's better. cc @zsxwing
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