markusthoemmes commented on a change in pull request #3072: Enhance kafka
message provider
URL:
https://github.com/apache/incubator-openwhisk/pull/3072#discussion_r160149157
##########
File path:
common/scala/src/main/scala/whisk/connector/kafka/KafkaConsumerConnector.scala
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@@ -21,46 +21,106 @@ import java.util.Properties
import scala.collection.JavaConversions.iterableAsScalaIterable
import scala.collection.JavaConversions.seqAsJavaList
-import scala.concurrent.duration.Duration
-import scala.concurrent.duration.DurationInt
-import scala.concurrent.duration.FiniteDuration
-
+import scala.concurrent.duration._
+import scala.concurrent.Future
import org.apache.kafka.clients.consumer.ConsumerConfig
import org.apache.kafka.clients.consumer.KafkaConsumer
import org.apache.kafka.common.serialization.ByteArrayDeserializer
-
+import org.apache.kafka.common.errors.{InvalidMetadataException,
WakeupException}
+import akka.actor.ActorSystem
+import org.apache.kafka.common.KafkaException
import whisk.common.Logging
import whisk.core.connector.MessageConsumer
class KafkaConsumerConnector(kafkahost: String,
groupid: String,
topic: String,
+ actorSystem: ActorSystem,
override val maxPeek: Int = Int.MaxValue,
readeos: Boolean = true,
sessionTimeout: FiniteDuration = 30.seconds,
autoCommitInterval: FiniteDuration = 10.seconds,
maxPollInterval: FiniteDuration =
5.minutes)(implicit logging: Logging)
extends MessageConsumer {
+ implicit val ec = actorSystem.dispatcher
/**
* Long poll for messages. Method returns once message are available but no
later than given
* duration.
*
* @param duration the maximum duration for the long poll
*/
- override def peek(duration: Duration = 500.milliseconds) = {
- val records = consumer.poll(duration.toMillis)
- records map { r =>
- (r.topic, r.partition, r.offset, r.value)
+ override def peek(duration: Duration = 500.milliseconds,
+ retry: Int = 3): Iterable[(String, Int, Long,
Array[Byte])] = {
+ // Since kafka client can be infinitely blocked in poll(timeout), we
should interrupt it by wakeup() method
+ val wakeUpTask = actorSystem.scheduler.scheduleOnce(sessionTimeout) {
+ consumer.wakeup()
}
+
+ try {
+ val records = consumer.poll(duration.toMillis)
+ records map { r =>
+ (r.topic, r.partition, r.offset, r.value)
+ }
+ } catch {
+
+ /**
+ * Kafka Error handling strategy
+ *
+ * 1. Error we know of can be handled by retry
+ * - WakeupException: Exception we raise intentionally to prevent
hanging in consumer.poll(timeout)
+ * - InvalidMetadataException: An exception that may indicate the
client's metadata is out of date,
+ * includes NetworkException,
KafkaStorageException, LeaderNotAvailableException,
+ * NotLeaderForPartitionException,
UnknownTopicOrPartitionException.
+ *
+ * 2. Errors we don't know of just result in a restart of the
consumer/producer
+ *
+ */
+ case e: KafkaException =>
+ e match {
+ case _: WakeupException =>
+ if (retry > 0) {
+ logging.error(this, s"Poll timeout occurred, remain $retry
retries to peek")
+ peek(duration, retry - 1)
+ } else {
+ recreateConsumer()
+ throw e
+ }
+ case _: InvalidMetadataException =>
+ if (retry > 0) {
+ logging.error(this, s"${e.getMessage}: remain $retry retries to
peek")
+ wakeUpTask.cancel()
Review comment:
Isn't this redundant as it's again handled in `finally`?
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