viirya commented on a change in pull request #25856: [SPARK-29182][Core] Cache
preferred locations of checkpointed RDD
URL: https://github.com/apache/spark/pull/25856#discussion_r334694408
##########
File path: core/src/main/scala/org/apache/spark/rdd/ReliableCheckpointRDD.scala
##########
@@ -82,16 +84,38 @@ private[spark] class ReliableCheckpointRDD[T: ClassTag](
Array.tabulate(inputFiles.length)(i => new CheckpointRDDPartition(i))
}
- /**
- * Return the locations of the checkpoint file associated with the given
partition.
- */
- protected override def getPreferredLocations(split: Partition): Seq[String]
= {
+ // Cache of preferred locations of checkpointed files.
+ @transient private[spark] lazy val cachedPreferredLocations =
CacheBuilder.newBuilder()
+ .expireAfterWrite(
+ SparkEnv.get.conf.get(CACHE_CHECKPOINT_PREFERRED_LOCS_EXPIRE_TIME).get,
+ TimeUnit.MINUTES)
+ .build(
+ new CacheLoader[Partition, Seq[String]]() {
+ override def load(split: Partition): Seq[String] = {
+ getPartitionBlockLocations(split)
+ }
+ })
+
+ // Returns the block locations of given partition on file system.
+ private def getPartitionBlockLocations(split: Partition): Seq[String] = {
val status = fs.getFileStatus(
new Path(checkpointPath,
ReliableCheckpointRDD.checkpointFileName(split.index)))
val locations = fs.getFileBlockLocations(status, 0, status.getLen)
locations.headOption.toList.flatMap(_.getHosts).filter(_ != "localhost")
}
+ /**
+ * Return the locations of the checkpoint file associated with the given
partition.
+ */
+ protected override def getPreferredLocations(split: Partition): Seq[String]
= {
+ val cachedExpireTime =
SparkEnv.get.conf.get(CACHE_CHECKPOINT_PREFERRED_LOCS_EXPIRE_TIME)
Review comment:
good point!
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