Github user huaxingao commented on a diff in the pull request:
https://github.com/apache/spark/pull/11104#discussion_r52228031
--- Diff:
external/kafka/src/test/scala/org/apache/spark/streaming/kafka/KafkaStreamSuite.scala
---
@@ -65,12 +67,14 @@ class KafkaStreamSuite extends SparkFunSuite with
Eventually with BeforeAndAfter
val stream = KafkaUtils.createStream[String, String, StringDecoder,
StringDecoder](
ssc, kafkaParams, Map(topic -> 1), StorageLevel.MEMORY_ONLY)
- val result = new mutable.HashMap[String, Long]() with
mutable.SynchronizedMap[String, Long]
+ val result = new ConcurrentHashMap[String, Long].asScala
stream.map(_._2).countByValue().foreachRDD { r =>
val ret = r.collect()
ret.toMap.foreach { kv =>
- val count = result.getOrElseUpdate(kv._1, 0) + kv._2
- result.put(kv._1, count)
+ result.synchronized {
+ val count = result.getOrElseUpdate(kv._1, 0) + kv._2
--- End diff --
@holdenk
Thanks for your quick reply.
I initially changed
val count = result.getOrElseUpdate(kv._1, 0) + kv._2
to
result.putIfAbsent(kv._1, 0)
val count = result.get(kv._1) + kv._2_
but the test failed for me. I guess a different thread can come in between
of the two lines and the concurrency is not guaranteed any more. So I used
synchronized block instead.
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