Github user cloud-fan commented on a diff in the pull request:
https://github.com/apache/spark/pull/8687#discussion_r39155712
--- Diff: core/src/main/scala/org/apache/spark/rdd/PairRDDFunctions.scala
---
@@ -1051,6 +1049,15 @@ class PairRDDFunctions[K, V](self: RDD[(K, V)])
val jobAttemptId = newTaskAttemptID(jobtrackerID, stageId, isMap =
true, 0, 0)
val jobTaskContext = newTaskAttemptContext(wrappedConf.value,
jobAttemptId)
val jobCommitter = jobFormat.getOutputCommitter(jobTaskContext)
+
+ // If speculation is enabled, we only allow FileOutputCommitter.
+ val speculationEnabled = self.conf.getBoolean("spark.speculation",
false)
+ if (speculationEnabled && jobCommitter.getClass !=
+ classOf[org.apache.hadoop.mapreduce.lib.output.FileOutputCommitter])
{
+ throw new SparkException(s"Cannot use ${jobCommitter.getClass} as
output committer when" +
+ "speculation is enabled.")
+ }
+
--- End diff --
I agree this is a too strong limitation, but my concern is that: there is
possibility that a user-defined output formatter provides a direct output
committer which we should reject. However, these is no simple way to see if a
output committer is direct or not, so I just restrict it to
`FileOutputCommitter` only here.
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