ScrapCodes commented on a change in pull request #19096: [SPARK-21869][SS] A
cached Kafka producer should not be closed if any task is using it - adds inuse
tracking.
URL: https://github.com/apache/spark/pull/19096#discussion_r272541401
##########
File path:
external/kafka-0-10-sql/src/main/scala/org/apache/spark/sql/kafka010/CachedKafkaProducer.scala
##########
@@ -40,81 +90,114 @@ private[kafka010] object CachedKafkaProducer extends
Logging {
"spark.kafka.producer.cache.timeout",
s"${defaultCacheExpireTimeout}ms")).getOrElse(defaultCacheExpireTimeout)
- private val cacheLoader = new CacheLoader[Seq[(String, Object)], Producer] {
- override def load(config: Seq[(String, Object)]): Producer = {
- val configMap = config.map(x => x._1 -> x._2).toMap.asJava
- createKafkaProducer(configMap)
+ private val cacheLoader = new CacheLoader[Seq[(String, Object)],
CachedKafkaProducer] {
+ override def load(params: Seq[(String, Object)]): CachedKafkaProducer = {
+ CachedKafkaProducer(kafkaParams = params)
}
}
- private val removalListener = new RemovalListener[Seq[(String, Object)],
Producer]() {
+ private val closeQueue = new ConcurrentLinkedQueue[CachedKafkaProducer]()
+
+ private val removalListener = new RemovalListener[Seq[(String, Object)],
CachedKafkaProducer]() {
override def onRemoval(
- notification: RemovalNotification[Seq[(String, Object)], Producer]):
Unit = {
- val paramsSeq: Seq[(String, Object)] = notification.getKey
- val producer: Producer = notification.getValue
- logDebug(
- s"Evicting kafka producer $producer params: $paramsSeq, due to
${notification.getCause}")
- close(paramsSeq, producer)
+ notification: RemovalNotification[Seq[(String, Object)],
CachedKafkaProducer]): Unit = {
+ val producer: CachedKafkaProducer = notification.getValue
+ if (producer.inUse()) {
+ logDebug(s"Evicting kafka producer $producer, due to
${notification.getCause}.")
+ // When `inuse` producer is evicted we wait for it to be released
before finally closing it.
+ closeQueue.add(producer)
+ producer.unCache()
+ } else {
+ close(producer)
+ }
}
}
- private lazy val guavaCache: LoadingCache[Seq[(String, Object)], Producer] =
+ private lazy val guavaCache: LoadingCache[Seq[(String, Object)],
CachedKafkaProducer] =
CacheBuilder.newBuilder().expireAfterAccess(cacheExpireTimeout,
TimeUnit.MILLISECONDS)
.removalListener(removalListener)
- .build[Seq[(String, Object)], Producer](cacheLoader)
-
- private def createKafkaProducer(producerConfiguration: ju.Map[String,
Object]): Producer = {
- val updatedKafkaProducerConfiguration =
- KafkaConfigUpdater("executor", producerConfiguration.asScala.toMap)
- .setAuthenticationConfigIfNeeded()
- .build()
- val kafkaProducer: Producer = new
Producer(updatedKafkaProducerConfiguration)
- logDebug(s"Created a new instance of KafkaProducer for
$updatedKafkaProducerConfiguration.")
- kafkaProducer
- }
+ .build[Seq[(String, Object)], CachedKafkaProducer](cacheLoader)
/**
* Get a cached KafkaProducer for a given configuration. If matching
KafkaProducer doesn't
* exist, a new KafkaProducer will be created. KafkaProducer is thread safe,
it is best to keep
* one instance per specified kafkaParams.
*/
- private[kafka010] def getOrCreate(kafkaParams: ju.Map[String, Object]):
Producer = {
- val paramsSeq: Seq[(String, Object)] = paramsToSeq(kafkaParams)
+ private[kafka010] def acquire(kafkaParamsMap: ju.Map[String, Object]):
CachedKafkaProducer = {
+ val paramsSeq: Seq[(String, Object)] = paramsToSeq(kafkaParamsMap)
try {
- guavaCache.get(paramsSeq)
+ val producer = this.synchronized {
+ val cachedKafkaProducer: CachedKafkaProducer =
guavaCache.get(paramsSeq)
+ cachedKafkaProducer.inUseCount.incrementAndGet()
+ logDebug(s"Granted producer $cachedKafkaProducer")
+ cachedKafkaProducer
+ }
+ producer
} catch {
- case e @ (_: ExecutionException | _: UncheckedExecutionException | _:
ExecutionError)
+ case e@(_: ExecutionException | _: UncheckedExecutionException | _:
ExecutionError)
if e.getCause != null =>
throw e.getCause
}
}
- private def paramsToSeq(kafkaParams: ju.Map[String, Object]): Seq[(String,
Object)] = {
- val paramsSeq: Seq[(String, Object)] = kafkaParams.asScala.toSeq.sortBy(x
=> x._1)
+ private def paramsToSeq(kafkaParamsMap: ju.Map[String, Object]):
Seq[(String, Object)] = {
+ val paramsSeq: Seq[(String, Object)] =
kafkaParamsMap.asScala.toSeq.sortBy(x => x._1)
paramsSeq
}
- /** For explicitly closing kafka producer */
- private[kafka010] def close(kafkaParams: ju.Map[String, Object]): Unit = {
- val paramsSeq = paramsToSeq(kafkaParams)
- guavaCache.invalidate(paramsSeq)
+ /* Release a kafka producer back to the kafka cache. We simply decrement
it's inuse count. */
+ private[kafka010] def release(producer: CachedKafkaProducer, failing:
Boolean): Unit = {
+ this.synchronized {
+ // It should be ok to call release multiple times on the same producer
object.
+ if (producer.inUse()) {
+ // So that we do not end up with -ve in-use counts.
+ producer.inUseCount.decrementAndGet()
+ logDebug(s"Released producer $producer.")
+ } else {
+ logWarning(s"Tried to release a not in use producer, $producer.")
+ }
+ if (failing) {
+ // If this producer is failing to write, we remove it from cache.
+ // So that it is re-created, eventually.
+ val cachedProducer = guavaCache.getIfPresent(producer.kafkaParams)
+ if (cachedProducer != null && cachedProducer.id == producer.id) {
+ logDebug(s"Invalidating a failing producer: $producer.")
+ guavaCache.invalidate(producer.kafkaParams)
+ }
+ }
+ }
+ if (!producer.inUse() && !producer.isCached) {
Review comment:
The purpose of closeQueue is, when an inuse producer is evicted by guava
cache, due to a long running task. Then in such rare cases, closeQueue will
hold the producer until it is finally released by all the task. Two important
properties to note, 1) while the producer exists in the closeQueue, it cannot
be acquired by any new tasks. 2) Once all the tasks have released it, then it
is closed and removed from the closeQueue.
Currently, the answers to the following question is not clear. Please feel
free to help me, anyone.
How closeQueue is just for mitigation of inCount goes out of sync?
How does race condition happens when isCached is true and object is not
added to closeQueue Or vice-versa?
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