Github user marmbrus commented on a diff in the pull request:
https://github.com/apache/spark/pull/17308#discussion_r118389504
--- Diff:
external/kafka-0-10-sql/src/main/scala/org/apache/spark/sql/kafka010/CachedKafkaProducer.scala
---
@@ -0,0 +1,174 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.kafka010
+
+import java.{util => ju}
+import java.util.concurrent.{ConcurrentMap, TimeUnit}
+import javax.annotation.concurrent.GuardedBy
+
+import com.google.common.cache.{Cache, CacheBuilder, RemovalListener,
RemovalNotification}
+import org.apache.kafka.clients.producer.KafkaProducer
+import scala.collection.JavaConverters._
+import scala.collection.immutable.SortedMap
+import scala.collection.mutable
+import scala.util.control.NonFatal
+
+import org.apache.spark.SparkEnv
+import org.apache.spark.internal.Logging
+import org.apache.spark.util.ShutdownHookManager
+
+private[kafka010] object CachedKafkaProducer extends Logging {
+
+ private type Producer = KafkaProducer[Array[Byte], Array[Byte]]
+
+ private lazy val cacheExpireTimeout: Long =
+ SparkEnv.get.conf.getTimeAsMs("spark.kafka.producer.cache.timeout",
"10m")
+
+ private val removalListener = new RemovalListener[String, Producer]() {
+ override def onRemoval(notification: RemovalNotification[String,
Producer]): Unit = {
+ val uid: String = notification.getKey
+ val producer: Producer = notification.getValue
+ logDebug(s"Evicting kafka producer $producer uid: $uid, due to
${notification.getCause}")
+ close(uid, producer)
+ }
+ }
+
+ private lazy val guavaCache: Cache[String, Producer] =
CacheBuilder.newBuilder()
+ .expireAfterAccess(cacheExpireTimeout, TimeUnit.MILLISECONDS)
+ .removalListener(removalListener)
+ .build[String, Producer]()
+
+ ShutdownHookManager.addShutdownHook { () =>
+ clear()
+ }
+
+ private def createKafkaProducer(
+ producerConfiguration: ju.Map[String, Object]): Producer = {
+ val uid = getUniqueId(producerConfiguration)
+ val kafkaProducer: Producer = new Producer(producerConfiguration)
+ guavaCache.put(uid.toString, kafkaProducer)
+ logDebug(s"Created a new instance of KafkaProducer for
$producerConfiguration.")
+ kafkaProducer
+ }
+
+ private def getUniqueId(kafkaParams: ju.Map[String, Object]): String = {
+ val uid =
kafkaParams.get(CanonicalizeKafkaParams.sparkKafkaParamsUniqueId)
+ assert(uid != null, s"KafkaParams($kafkaParams) not canonicalized.")
+ uid.toString
+ }
+
+ /**
+ * 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 = synchronized {
+ val params = if
(!CanonicalizeKafkaParams.isCanonicalized(kafkaParams)) {
+ CanonicalizeKafkaParams.computeUniqueCanonicalForm(kafkaParams)
+ } else {
+ kafkaParams
+ }
+ val uid = getUniqueId(params)
+
Option(guavaCache.getIfPresent(uid)).getOrElse(createKafkaProducer(params))
+ }
+
+ /** For explicitly closing kafka producer */
+ private[kafka010] def close(kafkaParams: ju.Map[String, Object]): Unit =
{
+ val params = if
(!CanonicalizeKafkaParams.isCanonicalized(kafkaParams)) {
+ CanonicalizeKafkaParams.computeUniqueCanonicalForm(kafkaParams)
+ } else kafkaParams
+ val uid = getUniqueId(params)
+ guavaCache.invalidate(uid)
+ }
+
+ /** Auto close on cache evict */
+ private def close(uid: String, producer: Producer): Unit = {
+ try {
+ val outcome = CanonicalizeKafkaParams.remove(
+ new ju.HashMap[String, Object](
+ Map(CanonicalizeKafkaParams.sparkKafkaParamsUniqueId ->
uid).asJava))
+ logDebug(s"Removed kafka params from cache: $outcome.")
+ logInfo(s"Closing the KafkaProducer with uid: $uid.")
+ producer.close()
+ } catch {
+ case NonFatal(e) => logWarning("Error while closing kafka
producer.", e)
+ }
+ }
+
+ private def clear(): Unit = {
+ logInfo("Cleaning up guava cache.")
+ guavaCache.invalidateAll()
+ }
+
+ // Intended for testing purpose only.
+ private def getAsMap: ConcurrentMap[String, Producer] =
guavaCache.asMap()
+}
+
+/**
+ * Canonicalize kafka params i.e. append a unique internal id to kafka
params, if it already does
+ * not exist. This is done to ensure, we have only one set of kafka
parameters associated with a
+ * unique ID.
+ */
+private[kafka010] object CanonicalizeKafkaParams extends Logging {
--- End diff --
This seems kind of complicated also. Since we know these are always coming
from `Data[Stream/Frame]Writer` and that will always give you `Map[String,
String]` (and we expect the number of options here to be small). Could we just
make the key for the cache a sorted `Seq[(String, String)]` rather than invent
another GUID?
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