Github user rxin commented on a diff in the pull request:
https://github.com/apache/spark/pull/3259#discussion_r20400510
--- Diff:
core/src/main/scala/org/apache/spark/network/nio/ConnectionManager.scala ---
@@ -899,22 +904,41 @@ private[nio] class ConnectionManager(
: Future[Message] = {
val promise = Promise[Message]()
- val timeoutTask = new TimerTask {
- override def run(): Unit = {
+ // It's important that the TimerTask doesn't capture a reference to
`message`, which can cause
+ // memory leaks since cancelled TimerTasks won't necessarily be
garbage collected until the time
+ // at which they would originally be scheduled to run. Therefore,
extract the message id
+ // from outside of the TimerTask closure (see SPARK-4393 for more
context).
+ val messageId = message.id
+ // Keep a weak reference to the promise so that the completed promise
may be garbage-collected
+ val promiseReference = new WeakReference(promise)
+ val timeoutTask: TimerTask = new TimerTask {
+ override def run(timeout: Timeout): Unit = {
messageStatuses.synchronized {
- messageStatuses.remove(message.id).foreach ( s => {
+ messageStatuses.remove(messageId).foreach ( s => {
val e = new IOException("sendMessageReliably failed because
ack " +
s"was not received within $ackTimeout sec")
- if (!promise.tryFailure(e)) {
- logWarning("Ignore error because promise is completed", e)
+ Option(promiseReference.get) match {
--- End diff --
why not
```scala
val p = promiseReference.get
if (p == null) {
...
} else {
...
}
```
?
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