Github user JoshRosen commented on a diff in the pull request:
https://github.com/apache/spark/pull/4066#discussion_r23990802
--- Diff: core/src/main/scala/org/apache/spark/SparkHadoopWriter.scala ---
@@ -105,24 +106,61 @@ class SparkHadoopWriter(@transient jobConf: JobConf)
def commit() {
val taCtxt = getTaskContext()
val cmtr = getOutputCommitter()
- if (cmtr.needsTaskCommit(taCtxt)) {
+
+ // Called after we have decided to commit
+ def performCommit(): Unit = {
try {
cmtr.commitTask(taCtxt)
- logInfo (taID + ": Committed")
+ logInfo (s"$taID: Committed")
} catch {
- case e: IOException => {
+ case e: IOException =>
logError("Error committing the output of task: " + taID.value, e)
cmtr.abortTask(taCtxt)
throw e
+ }
+ }
+
+ // First, check whether the task's output has already been committed
by some other attempt
+ if (cmtr.needsTaskCommit(taCtxt)) {
+ // The task output needs to be committed, but we don't know whether
some other task attempt
+ // might be racing to commit the same output partition. Therefore,
coordinate with the driver
+ // in order to determine whether this attempt can commit.
+ val shouldCoordinateWithDriver: Boolean = {
+ val sparkConf = SparkEnv.get.conf
+ // We only need to coordinate with the driver if there are
multiple concurrent task
+ // attempts, which should only occur if speculation is enabled
+ val speculationEnabled = sparkConf.getBoolean("spark.speculation",
false)
+ // This (undocumented) setting is an escape-hatch in case the
commit code introduces bugs
+ //
sparkConf.getBoolean("spark.hadoop.outputCommitCoordination.enabled",
speculationEnabled)
+
+ // TODO: revert this before merging the PR; this is enabled so
this code path is exercised
+ // by more tests (even though it might not be _necessary_, it
should be _safe_ to do the
+ // extra coordination)
+ true
--- End diff --
I added this line in just so that Jenkins would run the CheckpointSuite
test that had previously failed. It would be good to try to extract a unit
test out of that.
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