zsxwing commented on a change in pull request #33002:
URL: https://github.com/apache/spark/pull/33002#discussion_r655627123
##########
File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/ManifestFileCommitProtocol.scala
##########
@@ -113,12 +113,15 @@ class ManifestFileCommitProtocol(jobId: String, path:
String)
override def newTaskTempFile(
taskContext: TaskAttemptContext, dir: Option[String], ext: String):
String = {
- // The file name looks like
part-r-00000-2dd664f9-d2c4-4ffe-878f-c6c70c1fb0cb_00003.gz.parquet
- // Note that %05d does not truncate the split number, so if we have more
than 100000 tasks,
+ // 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.
+ 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
- val uuid = UUID.randomUUID.toString
- val filename = f"part-$split%05d-$uuid$ext"
Review comment:
> 2\. The file output committe for streaming does not use staging
directories. It writes files to the final path directly and uses a manifest
file to track the committed files. Thus, partition ID is not sufficient to
avoid file name collision. That's why we add a fresh UUID to the file name.
Could you explain this? Currently `ManifestFileCommitProtocol` should always
pick up a new uuid for each file.
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