Rebalance-Listener anstatt Wegwerfen der Map

[demos/kafka/training] / src / main / java / de / juplo / kafka / EndlessConsumer.java

diff --git a/src/main/java/de/juplo/kafka/EndlessConsumer.java b/src/main/java/de/juplo/kafka/EndlessConsumer.java
index 127c3d3..9aa8152 100644 (file)
--- a/src/main/java/de/juplo/kafka/EndlessConsumer.java
+++ b/src/main/java/de/juplo/kafka/EndlessConsumer.java
@@ -1,18 +1,17 @@
 package de.juplo.kafka;
 
 import lombok.extern.slf4j.Slf4j;
+import org.apache.kafka.clients.consumer.ConsumerRebalanceListener;
 import org.apache.kafka.clients.consumer.ConsumerRecord;
 import org.apache.kafka.clients.consumer.ConsumerRecords;
 import org.apache.kafka.clients.consumer.KafkaConsumer;
+import org.apache.kafka.common.TopicPartition;
 import org.apache.kafka.common.errors.WakeupException;
 import org.apache.kafka.common.serialization.StringDeserializer;
 
 import javax.annotation.PreDestroy;
 import java.time.Duration;
-import java.util.Arrays;
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Properties;
+import java.util.*;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Future;
@@ -34,7 +33,7 @@ public class EndlessConsumer implements Runnable
   private KafkaConsumer<String, String> consumer = null;
   private Future<?> future = null;
 
-  private Map<Integer, Map<String, Integer>> seen;
+  private final Map<Integer, Map<String, Integer>> seen = new HashMap<>();
 
 
   public EndlessConsumer(
@@ -63,15 +62,27 @@ public class EndlessConsumer implements Runnable
       props.put("group.id", groupId);
       props.put("client.id", id);
       props.put("auto.offset.reset", autoOffsetReset);
+      props.put("metadata.max.age.ms", "1000");
       props.put("key.deserializer", StringDeserializer.class.getName());
       props.put("value.deserializer", StringDeserializer.class.getName());
 
       this.consumer = new KafkaConsumer<>(props);
 
       log.info("{} - Subscribing to topic {}", id, topic);
-      consumer.subscribe(Arrays.asList(topic));
+      consumer.subscribe(Arrays.asList(topic), new ConsumerRebalanceListener()
+      {
+        @Override
+        public void onPartitionsRevoked(Collection<TopicPartition> partitions)
+        {
+          partitions.forEach(tp -> seen.remove(tp.partition()));
+        }
 
-      seen = new HashMap<>();
+        @Override
+        public void onPartitionsAssigned(Collection<TopicPartition> partitions)
+        {
+          partitions.forEach(tp -> seen.put(tp.partition(), new HashMap<>()));
+        }
+      });
 
       while (true)
       {
@@ -95,10 +106,6 @@ public class EndlessConsumer implements Runnable
 
           Integer partition = record.partition();
           String key = record.key() == null ? "NULL" : record.key();
-
-          if (!seen.containsKey(partition))
-            seen.put(partition, new HashMap<>());
-
           Map<String, Integer> byKey = seen.get(partition);
 
           if (!byKey.containsKey(key))
@@ -137,7 +144,6 @@ public class EndlessConsumer implements Runnable
               key);
         }
       }
-      seen = null;
 
       log.info("{} - Consumer-Thread exiting", id);
     }