[英]Spark Kafka streaming doesn't distribute consumer load on worker nodes
我創建了以下應用程序,可在 20 秒窗口內打印特定的消息事件:
public class SparkMain {
public static void main(String[] args) {
Map<String, Object> kafkaParams = new HashMap<>();
kafkaParams.put(BOOTSTRAP_SERVERS_CONFIG, "localhost:9092, localhost:9093");
kafkaParams.put(GROUP_ID_CONFIG, "spark-consumer-id");
kafkaParams.put(KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
kafkaParams.put(VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
// events topic has 2 partitions
Collection<String> topics = Arrays.asList("events");
// local[*] Run Spark locally with as many worker threads as logical cores on your machine.
SparkConf conf = new SparkConf().setMaster("local[*]").setAppName("SsvpSparkStreaming");
// Create context with a 1 seconds batch interval
JavaStreamingContext streamingContext =
new JavaStreamingContext(conf, Durations.seconds(1));
JavaInputDStream<ConsumerRecord<String, String>> stream =
KafkaUtils.createDirectStream(
streamingContext,
LocationStrategies.PreferConsistent(),
ConsumerStrategies.<String, String>Subscribe(topics, kafkaParams)
);
// extract event name from record value
stream.map(new Function<ConsumerRecord<String, String>, String>() {
@Override
public String call(ConsumerRecord<String, String> rec) throws Exception {
return rec.value().substring(0, 5);
}})
// filter events
.filter(new Function<String, Boolean>() {
@Override
public Boolean call(String eventName) throws Exception {
return eventName.contains("msg");
}})
// count with 20sec window and 5 sec slide duration
.countByValueAndWindow(Durations.seconds(20), Durations.seconds(5))
.print();
streamingContext.checkpoint("c:\\projects\\spark\\");
streamingContext.start();
try {
streamingContext.awaitTermination();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
在日志中運行 main 方法后,我只看到獲得兩個分區的單個使用者初始化:
2018-10-25 18:25:56,007 INFO [org.apache.kafka.common.utils.LogContext$KafkaLogger.info] - <[Consumer clientId=consumer-1, groupId=spark-consumer-id] 設置新分配的分區[事件-0,事件-1]>
消費者的數量不是應該等於spark worker的數量嗎? 按照https://spark.apache.org/docs/2.3.2/submitting-applications.html#master-urls
local[*] 表示 -在本地運行 Spark,使用與機器上的邏輯內核一樣多的工作線程。
我有 8 核 CPU,所以我希望應該創建 8 個消費者或至少 2 個消費者,並且每個消費者都獲得“事件”主題的分區(2 個分區)。
在我看來,我需要運行一個完整的獨立 spark master-worker 集群,其中包含 2 個節點,其中每個節點都啟動自己的消費者......
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