Github user aarondav commented on a diff in the pull request:
https://github.com/apache/spark/pull/621#discussion_r12252315
--- Diff: core/src/main/scala/org/apache/spark/deploy/SparkHadoopUtil.scala
---
@@ -24,25 +24,30 @@ import org.apache.hadoop.mapred.JobConf
import org.apache.hadoop.security.Credentials
import org.apache.hadoop.security.UserGroupInformation
-import org.apache.spark.{SparkContext, SparkException}
+import org.apache.spark.{Logging, SparkContext, SparkException}
import scala.collection.JavaConversions._
/**
* Contains util methods to interact with Hadoop from Spark.
*/
-class SparkHadoopUtil {
+class SparkHadoopUtil extends Logging {
val conf: Configuration = newConfiguration()
UserGroupInformation.setConfiguration(conf)
+ // IMPORTANT NOTE: If this function is going to be called repeated in
the same process
+ // you need to look https://issues.apache.org/jira/browse/HDFS-3545 and
possibly
+ // do a FileSystem.closeAllForUGI in order to avoid leaking Filesystems
def runAsUser(user: String)(func: () => Unit) {
--- End diff --
Since the usage of this is now distributed to many places throughout Spark,
can we add a comment for people who have no clue why it's there? Just something
like "Runs the given function with a Hadoop UserGroupInformation as a thread
local variable (distributed to child threads), used for authenticating HDFS and
YARN calls."
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