Github user jerryshao commented on a diff in the pull request:
https://github.com/apache/spark/pull/5064#discussion_r26638830
--- Diff: core/src/main/scala/org/apache/spark/executor/TaskMetrics.scala
---
@@ -212,10 +213,26 @@ class TaskMetrics extends Serializable {
private[spark] def updateInputMetrics(): Unit = synchronized {
inputMetrics.foreach(_.updateBytesRead())
}
+
+ @throws(classOf[IOException])
+ private def readObject(in: ObjectInputStream): Unit =
Utils.tryOrIOException {
+ in.defaultReadObject()
+ // Get the hostname from cached data, since hostname is the order of
number of nodes in
+ // cluster, so using cached hostname will decrease the object number
and alleviate the GC
+ // overhead.
+ _hostname = TaskMetrics.getCachedHostName(_hostname)
+ }
}
private[spark] object TaskMetrics {
+ private val hostNameCache = new ConcurrentHashMap[String, String]()
--- End diff --
I think the size of the cache will at most be as large as the cluster size,
so weak ref map may not be so necessary from my understanding.
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