Github user zsxwing commented on a diff in the pull request:
https://github.com/apache/spark/pull/3661#discussion_r23372367
--- Diff:
streaming/src/main/scala/org/apache/spark/streaming/ContextWaiter.scala ---
@@ -17,30 +17,63 @@
package org.apache.spark.streaming
+import java.util.concurrent.TimeUnit
+import java.util.concurrent.locks.ReentrantLock
+
private[streaming] class ContextWaiter {
+
+ private val lock = new ReentrantLock()
+ private val condition = lock.newCondition()
+
+ // Guarded by "lock"
private var error: Throwable = null
- private var stopped: Boolean = false
- def notifyError(e: Throwable) = synchronized {
- error = e
- notifyAll()
- }
+ // Guarded by "lock"
+ private var stopped: Boolean = false
- def notifyStop() = synchronized {
- stopped = true
- notifyAll()
+ def notifyError(e: Throwable): Unit = {
+ lock.lock()
+ try {
+ error = e
+ condition.signalAll()
+ } finally {
+ lock.unlock()
+ }
}
- def waitForStopOrError(timeout: Long = -1) = synchronized {
- // If already had error, then throw it
- if (error != null) {
- throw error
+ def notifyStop(): Unit = {
+ lock.lock()
+ try {
+ stopped = true
+ condition.signalAll()
+ } finally {
+ lock.unlock()
}
+ }
- // If not already stopped, then wait
- if (!stopped) {
- if (timeout < 0) wait() else wait(timeout)
+ /**
+ * Return `true` if it's stopped; or throw the reported error if
`notifyError` has been called; or
+ * `false` if the waiting time detectably elapsed before return from the
method.
+ */
+ def waitForStopOrError(timeout: Long = -1): Boolean = {
--- End diff --
> In hindsight, instead of modeling awaitTermination against Akka
ActorSystem's awaitTermination (which return Unit) , I should have modeled it
like Java ExecutorService's awaitTermination which returns a Boolean. Now its
not possible to change the API without breaking compatiblity. :(
@tdas, Sorry that I forgot to reply you. You said you designed it just like
Akka `ActorSystem.awaitTermination`. But
[ActorSystem.awaitTermination](https://github.com/akka/akka/blob/master/akka-actor/src/main/scala/akka/actor/ActorSystem.scala#L394)
will throw a TimeoutException in case of timeout.
```Scala
/**
* Block current thread until the system has been shutdown, or the
specified
* timeout has elapsed. This will block until after all on termination
* callbacks have been run.
*
* @throws TimeoutException in case of timeout
*/
def awaitTermination(timeout: Duration): Unit
```
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