我無法找到高級消費者的生命週期描述。我在0.8.2.2上,我不能使用來自kafka客戶的「現代」消費者。這裏是我的代碼:卡夫卡的高級消費者API生命週期0.8
def consume(numberOfEvents: Int, await: Duration = 100.millis): List[MessageEnvelope] = {
val consumerProperties = new Properties()
consumerProperties.put("zookeeper.connect", kafkaConfig.zooKeeperConnectString)
consumerProperties.put("group.id", consumerGroup)
consumerProperties.put("auto.offset.reset", "smallest")
val consumer = Consumer.create(new ConsumerConfig(consumerProperties))
try {
val messageStreams = consumer.createMessageStreams(
Predef.Map(kafkaConfig.topic -> 1),
new DefaultDecoder,
new MessageEnvelopeDecoder)
val receiveMessageFuture = Future[List[MessageEnvelope]] {
messageStreams(kafkaConfig.topic)
.flatMap(stream => stream.take(numberOfEvents).map(_.message()))
}
Await.result(receiveMessageFuture, await)
} finally {
consumer.shutdown()
}
我不清楚。我應該在每次檢索消息後關閉消費者,還是保留實例並將其重新用於消息提取?我認爲重用實例是正確的方式,但找不到一些文章/最佳實踐。
我想重用消費者和/或messageStreams。它不適合我,我找不到原因。
如果我嘗試重用messageStreams,我得到異常:
2017-04-17_19:57:57.088 ERROR MessageEnvelopeConsumer - Error while awaiting for messages java.lang.IllegalStateException: Iterator is in failed state
java.lang.IllegalStateException: Iterator is in failed state
at kafka.utils.IteratorTemplate.hasNext(IteratorTemplate.scala:54)
at scala.collection.IterableLike$class.take(IterableLike.scala:134)
at kafka.consumer.KafkaStream.take(KafkaStream.scala:25)
發生在這裏:
def consume(numberOfEvents: Int, await: Duration = 100.millis): List[MessageEnvelope] = {
try {
val receiveMessageFuture = Future[List[MessageEnvelope]] {
messageStreams(kafkaConfig.topic)
.flatMap(stream => stream.take(numberOfEvents).map(_.message()))
}
Try(Await.result(receiveMessageFuture, await)) match {
case Success(result) => result
case Failure(_: TimeoutException) => List.empty
case Failure(e) =>
// ===> never got any message from topic
logger.error(s"Error while awaiting for messages ${e.getClass.getName}: ${e.getMessage}", e)
List.empty
}
} catch {
case e: Exception =>
logger.warn(s"Error while consuming messages", e)
List.empty
}
}
我試圖創建messageStreams每次:
沒有運氣...
2017-04-17_20:02:44.236 WARN MessageEnvelopeConsumer - Error while consuming messages
kafka.common.MessageStreamsExistException: ZookeeperConsumerConnector can create message streams at most once
at kafka.consumer.ZookeeperConsumerConnector.createMessageStreams(ZookeeperConsumerConnector.scala:151)
at MessageEnvelopeConsumer.consume(MessageEnvelopeConsumer.scala:47)
Ha ppens這裏:
def consume(numberOfEvents: Int, await: Duration = 100.millis): List[MessageEnvelope] = {
try {
val messageStreams = consumer.createMessageStreams(
Predef.Map(kafkaConfig.topic -> 1),
new DefaultDecoder,
new MessageEnvelopeDecoder)
val receiveMessageFuture = Future[List[MessageEnvelope]] {
messageStreams(kafkaConfig.topic)
.flatMap(stream => stream.take(numberOfEvents).map(_.message()))
}
Try(Await.result(receiveMessageFuture, await)) match {
case Success(result) => result
case Failure(_: TimeoutException) => List.empty
case Failure(e) =>
logger.error(s"Error while awaiting for messages ${e.getClass.getName}: ${e.getMessage}", e)
List.empty
}
} catch {
case e: Exception =>
// ===> now exception raised here
logger.warn(s"Error while consuming messages", e)
List.empty
}
}
UPD
我使用的基於迭代器的方法。它看起來是這樣的:
// consumerProperties.put("consumer.timeout.ms", "100")
private lazy val consumer: ConsumerConnector = Consumer.create(new ConsumerConfig(consumerProperties))
private lazy val messageStreams: Seq[KafkaStream[Array[Byte], MessageEnvelope]] =
consumer.createMessageStreamsByFilter(Whitelist(kafkaConfig.topic), 1, new DefaultDecoder, new MessageEnvelopeDecoder)
private lazy val iterator: ConsumerIterator[Array[Byte], MessageEnvelope] = {
val stream = messageStreams.head
stream.iterator()
}
def consume(): List[MessageEnvelope] = {
try {
if (iterator.hasNext) {
val fromKafka: MessageAndMetadata[Array[Byte], MessageEnvelope] = iterator.next
List(fromKafka.message())
} else {
List.empty
}
} catch {
case _: ConsumerTimeoutException =>
List.empty
case e: Exception =>
logger.warn(s"Error while consuming messages", e)
List.empty
}
}
現在我想弄清楚它是否會自動提交偏移ZK ...
嗨,試圖實施你的方法。遇到了其他問題。你能檢查我的更新嗎? – Sergey
因此,它只能在一種情況下作爲「預期」(取得的消息)工作:當我創建消費者,messageStreams,獲取消息並關閉消費者時。 – Sergey