Fix: record tracker does not support concurrent event batch removal

src/main/java/com/splunk/kafka/connect/KafkaRecordTracker.java

@@ -27,6 +27,7 @@
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.ConcurrentNavigableMap;
 import java.util.concurrent.ConcurrentSkipListMap;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicLong;
 
 import org.slf4j.Logger;
@@ -39,6 +40,7 @@ final class KafkaRecordTracker {
     private ConcurrentLinkedQueue<EventBatch> failed;
     private volatile Map<TopicPartition, OffsetAndMetadata> offsets;
     private Collection<TopicPartition> partitions;
+    private AtomicBoolean removingEventsInProgress = new AtomicBoolean(false);
 
     public KafkaRecordTracker() {
         all = new ConcurrentHashMap<>();
@@ -58,35 +60,58 @@ public void removeAckedEventBatches(final List<EventBatch> batches) {
         log.debug("received acked event batches={}", batches);
         /* Loop all *assigned* partitions to find the lowest consecutive
          * HEC-commited offsets. A batch could contain events coming from a
-         * variety of topic/partitions, and scanning those events coulb be
+         * variety of topic/partitions, and scanning those events could be
          * expensive.
          * Note that if some events are tied to an unassigned partition those
-         * offsets won't be able to be commited.
+         * offsets won't be able to be committed.
          */
-        for (TopicPartition tp : partitions) {
-            ConcurrentNavigableMap<Long, EventBatch> tpRecords = all.get(tp);
-            if (tpRecords == null) {
-                continue;  // nothing to remove in this case
-            }
-            long offset = -1;
-            Iterator<Map.Entry<Long, EventBatch>> iter = tpRecords.entrySet().iterator();
-            for (; iter.hasNext();) {
-                Map.Entry<Long, EventBatch> e = iter.next();
-                if (e.getValue().isCommitted()) {
-                    log.debug("processing offset {}", e.getKey());
-                    offset = e.getKey();
-                    iter.remove();
-                    total.decrementAndGet();
-                } else {
-                    break;
+        // With the current implementation, we don't need to let multiple threads cleaning events in parallel.
+        if (removingEventsInProgress.compareAndSet(false, true)) {
+            try {
+                long countOfEventsToRemove = 0;
+
+                for (TopicPartition tp : partitions) {
+                    ConcurrentNavigableMap<Long, EventBatch> tpRecords = all.get(tp);
+                    if (tpRecords == null) {
+                        continue;  // nothing to remove in this case
+                    }
+                    long offset = -1;
+                    Iterator<Map.Entry<Long, EventBatch>> iter = tpRecords.entrySet().iterator();
+                    for (; iter.hasNext(); ) {
+                        Map.Entry<Long, EventBatch> e = iter.next();
+                        if (e.getValue().isCommitted()) {
+                            log.debug("processing offset {}", e.getKey());
+                            offset = e.getKey();
+                            iter.remove();
+                            countOfEventsToRemove++;
+                        } else {
+                            break;
+                        }
+                    }
+                    if (offset >= 0) {
+                        offsets.put(tp, new OffsetAndMetadata(offset + 1));
+                    }
                 }
-            }
-            if (offset >= 0) {
-                offsets.put(tp, new OffsetAndMetadata(offset + 1));
+                decrementTotalEventCount(countOfEventsToRemove);
+            } finally {
+                removingEventsInProgress.set(false);
             }
         }
     }
 
+    private void decrementTotalEventCount(long countOfEventsToRemove) {
+        total.getAndUpdate(current -> {
+            if (current < countOfEventsToRemove) {
+                log.warn("Total event count ({}) is lower than the count ({}) we try to remove, resetting to 0",
+                        current,
+                        countOfEventsToRemove);
+                return 0;
+            } else {
+                return current - countOfEventsToRemove;
+            }
+        });
+    }
+
     public void addFailedEventBatch(final EventBatch batch) {
         if (!batch.isFailed()) {
             throw new RuntimeException("event batch was not failed");
@@ -180,7 +205,7 @@ public void cleanupAfterClosedPartitions(Collection<TopicPartition> partitions)
             log.warn("purge events={} from closed partitions={}",
                      countOfEventsToRemove, partitions);
             all.keySet().removeAll(partitions);
-            total.addAndGet(-1L * countOfEventsToRemove);
+            decrementTotalEventCount(countOfEventsToRemove);
         }
     }
 }

src/test/java/com/splunk/hecclient/UnitUtil.java

@@ -35,6 +35,15 @@ public static EventBatch createBatch() {
         return batch;
     }
 
+    public static EventBatch createMultiBatch(int count) {
+        EventBatch batch = new JsonEventBatch();
+        for (int i = 0; i < count; i++) {
+            Event event = new JsonEvent("ni-" + i, "hao-" + i);
+            batch.add(event);
+        }
+        return batch;
+    }
+
     public static EventBatch createRawEventBatch() {
         Event event = new RawEvent("ni", "hao");
         EventBatch batch = RawEventBatch.factory().build();

src/test/java/com/splunk/kafka/connect/KafkaRecordTrackerTest.java

@@ -27,6 +27,10 @@
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
 
 public class KafkaRecordTrackerTest {
     @Test
@@ -48,6 +52,38 @@ public void addNonFailedEventBatch() {
         tracker.addFailedEventBatch(batch);
     }
 
+    @Test
+    public void removeEventBatchMultiThread() {
+        List<EventBatch> batches = new ArrayList<>();
+        KafkaRecordTracker tracker = new KafkaRecordTracker();
+        tracker.open(createTopicPartitionList(500));
+
+        for (int i = 0; i < 100; i++) {
+            EventBatch batch = UnitUtil.createMultiBatch(500);
+            for (int j = 0; j < 500; j++) {
+                batch.getEvents().get(j).setTied(createSinkRecord(j, i * 1000 + j));
+            }
+            batch.commit();
+            batches.add(batch);
+            tracker.addEventBatch(batch);
+        }
+
+        Assert.assertEquals(50000, tracker.totalEvents());
+        ExecutorService executorService = Executors.newFixedThreadPool(2);
+        try {
+            Future<?> first = executorService.submit(() -> tracker.removeAckedEventBatches(batches));
+            Future<?> second = executorService.submit(() -> tracker.removeAckedEventBatches(batches));
+
+            first.get();
+            second.get();
+        } catch (ExecutionException | InterruptedException e) {
+            throw new RuntimeException(e);
+        } finally {
+            executorService.shutdown();
+        }
+
+        Assert.assertEquals(0, tracker.totalEvents());
+    }
     @Test
     public void addEventBatch() {
         List<EventBatch> batches = new ArrayList<>();
@@ -104,4 +140,16 @@ private List<TopicPartition> createTopicPartitionList() {
         tps.add(new TopicPartition("t", 1));
         return tps;
     }
+
+    private SinkRecord createSinkRecord(int partition, long offset) {
+        return new SinkRecord("t", partition, null, null, null, "ni, hao", offset);
+    }
+
+    private List<TopicPartition> createTopicPartitionList(int number) {
+        ArrayList<TopicPartition> tps = new ArrayList<>();
+        for (int i = 0; i < number; i++) {
+            tps.add(new TopicPartition("t", i));
+        }
+        return tps;
+    }
 }

target/site/jacoco/jacoco.csv

@@ -1,42 +1,42 @@
 GROUP,PACKAGE,CLASS,INSTRUCTION_MISSED,INSTRUCTION_COVERED,BRANCH_MISSED,BRANCH_COVERED,LINE_MISSED,LINE_COVERED,COMPLEXITY_MISSED,COMPLEXITY_COVERED,METHOD_MISSED,METHOD_COVERED
 splunk-kafka-connect,com.splunk.hecclient,HttpClientBuilder.new Credentials() {...},10,0,0,0,3,0,3,0,3,0
-splunk-kafka-connect,com.splunk.hecclient,EventBatch.HttpEventBatchEntity,0,40,0,2,0,8,0,7,0,6
+splunk-kafka-connect,com.splunk.hecclient,EventBatch.HttpEventBatchEntity,0,40,0,2,0,9,0,7,0,6
 splunk-kafka-connect,com.splunk.hecclient,HttpClientBuilder.new HostnameVerifier() {...},2,6,0,0,1,1,1,1,1,1
 splunk-kafka-connect,com.splunk.hecclient,HttpClientBuilder.new TrustStrategy() {...},2,6,0,0,1,1,1,1,1,1
-splunk-kafka-connect,com.splunk.hecclient,Hec,38,298,4,14,9,73,4,20,0,15
-splunk-kafka-connect,com.splunk.hecclient,ConcurrentHec,23,195,1,13,5,48,1,16,0,10
+splunk-kafka-connect,com.splunk.hecclient,Hec,38,298,4,14,10,74,4,20,0,15
+splunk-kafka-connect,com.splunk.hecclient,ConcurrentHec,23,196,1,13,6,50,1,16,0,10
 splunk-kafka-connect,com.splunk.hecclient,HecException,0,9,0,0,0,4,0,2,0,2
-splunk-kafka-connect,com.splunk.hecclient,LoadBalancer,47,363,8,24,12,88,7,23,1,13
-splunk-kafka-connect,com.splunk.hecclient,HecAckPoller,122,711,11,45,28,157,9,44,0,25
-splunk-kafka-connect,com.splunk.hecclient,HecAckPoller.RunAckQuery,21,26,0,0,2,8,0,2,0,2
-splunk-kafka-connect,com.splunk.hecclient,HttpClientBuilder,69,132,0,4,17,46,2,13,2,11
-splunk-kafka-connect,com.splunk.hecclient,RawEvent,11,63,0,8,2,18,0,8,0,4
-splunk-kafka-connect,com.splunk.hecclient,RawEventBatch,22,168,1,9,8,46,3,17,2,13
-splunk-kafka-connect,com.splunk.hecclient,JsonEvent,22,60,0,8,5,21,0,11,0,7
+splunk-kafka-connect,com.splunk.hecclient,LoadBalancer,48,362,8,24,12,87,7,23,1,13
+splunk-kafka-connect,com.splunk.hecclient,HecAckPoller,122,711,11,45,34,160,9,44,0,25
+splunk-kafka-connect,com.splunk.hecclient,HecAckPoller.RunAckQuery,21,26,0,0,3,8,0,2,0,2
+splunk-kafka-connect,com.splunk.hecclient,HttpClientBuilder,69,132,0,4,16,46,2,13,2,11
+splunk-kafka-connect,com.splunk.hecclient,RawEvent,11,63,0,8,3,17,0,8,0,4
+splunk-kafka-connect,com.splunk.hecclient,RawEventBatch,22,169,1,9,8,45,3,17,2,13
+splunk-kafka-connect,com.splunk.hecclient,JsonEvent,22,60,0,8,6,21,0,11,0,7
 splunk-kafka-connect,com.splunk.hecclient,HecEmptyEventException,5,4,0,0,2,2,1,1,1,1
-splunk-kafka-connect,com.splunk.hecclient,HecChannel,0,116,0,12,0,36,0,22,0,16
-splunk-kafka-connect,com.splunk.hecclient,EventBatch,0,238,0,12,0,58,0,28,0,22
+splunk-kafka-connect,com.splunk.hecclient,HecChannel,0,116,0,12,0,35,0,22,0,16
+splunk-kafka-connect,com.splunk.hecclient,EventBatch,0,236,0,12,0,60,0,28,0,22
 splunk-kafka-connect,com.splunk.hecclient,HecNullEventException,5,4,0,0,2,2,1,1,1,1
 splunk-kafka-connect,com.splunk.hecclient,Event,3,204,0,6,1,67,1,29,1,26
 splunk-kafka-connect,com.splunk.hecclient,RawEventBatch.Builder,0,45,0,0,0,13,0,7,0,7
-splunk-kafka-connect,com.splunk.hecclient,Indexer,178,421,9,19,38,95,10,23,3,16
+splunk-kafka-connect,com.splunk.hecclient,Indexer,179,420,9,19,40,96,10,23,3,16
 splunk-kafka-connect,com.splunk.hecclient,EventBatch.GzipDataContentProducer,0,21,0,0,0,6,0,2,0,2
-splunk-kafka-connect,com.splunk.hecclient,HecAckPollResponse,0,43,0,4,0,8,0,5,0,3
-splunk-kafka-connect,com.splunk.hecclient,HecConfig,4,228,1,1,1,81,2,43,1,43
+splunk-kafka-connect,com.splunk.hecclient,HecAckPollResponse,0,43,0,4,0,9,0,5,0,3
+splunk-kafka-connect,com.splunk.hecclient,HecConfig,5,227,1,1,1,81,2,43,1,43
 splunk-kafka-connect,com.splunk.hecclient,Indexer.new Configuration() {...},21,0,0,0,4,0,2,0,2,0
-splunk-kafka-connect,com.splunk.hecclient,HecURIBuilder,6,59,0,4,2,14,0,4,0,2
+splunk-kafka-connect,com.splunk.hecclient,HecURIBuilder,6,59,0,4,2,13,0,4,0,2
 splunk-kafka-connect,com.splunk.hecclient,DoubleSerializer,0,15,0,0,0,4,0,2,0,2
 splunk-kafka-connect,com.splunk.hecclient,PostResponse,0,37,0,2,0,13,0,8,0,7
-splunk-kafka-connect,com.splunk.hecclient,ResponsePoller,34,79,1,7,7,22,3,11,2,8
-splunk-kafka-connect,com.splunk.hecclient,JsonEventBatch,19,33,2,2,7,10,3,6,2,5
+splunk-kafka-connect,com.splunk.hecclient,ResponsePoller,33,80,1,7,7,23,3,11,2,8
+splunk-kafka-connect,com.splunk.hecclient,JsonEventBatch,19,33,2,2,7,9,3,6,2,5
 splunk-kafka-connect,com.splunk.hecclient,EventBatch.HttpEventBatchEntity.new Enumeration() {...},0,44,0,4,0,4,0,5,0,3
 splunk-kafka-connect,com.splunk.kafka.connect,HecClientWrapper,3,3,0,0,1,1,1,1,1,1
-splunk-kafka-connect,com.splunk.kafka.connect,KafkaRecordTracker,22,315,4,22,6,68,4,26,0,17
-splunk-kafka-connect,com.splunk.kafka.connect,JacksonStructModule.StructSerializer,0,36,0,2,0,6,0,3,0,2
-splunk-kafka-connect,com.splunk.kafka.connect,VersionUtils,11,86,0,10,3,25,1,11,1,6
+splunk-kafka-connect,com.splunk.kafka.connect,KafkaRecordTracker,27,351,5,25,10,76,5,29,0,19
+splunk-kafka-connect,com.splunk.kafka.connect,JacksonStructModule.StructSerializer,0,36,0,2,0,7,0,3,0,2
+splunk-kafka-connect,com.splunk.kafka.connect,VersionUtils,11,86,0,10,4,26,1,11,1,6
 splunk-kafka-connect,com.splunk.kafka.connect,JacksonStructModule,0,10,0,0,0,3,0,1,0,1
 splunk-kafka-connect,com.splunk.kafka.connect,SplunkSinkRecord,74,188,14,14,22,47,18,9,5,8
-splunk-kafka-connect,com.splunk.kafka.connect,SplunkSinkConnectorConfig,5,1337,6,72,1,236,6,47,0,14
-splunk-kafka-connect,com.splunk.kafka.connect,SplunkSinkConnector,57,338,3,25,12,82,4,26,1,15
+splunk-kafka-connect,com.splunk.kafka.connect,SplunkSinkConnectorConfig,5,1269,6,72,1,198,6,47,0,14
+splunk-kafka-connect,com.splunk.kafka.connect,SplunkSinkConnector,57,383,4,30,11,85,5,28,1,15
 splunk-kafka-connect,com.splunk.kafka.connect,AbstractClientWrapper,0,3,0,0,0,1,0,1,0,1
-splunk-kafka-connect,com.splunk.kafka.connect,SplunkSinkTask,415,1134,58,84,66,252,48,56,3,30
+splunk-kafka-connect,com.splunk.kafka.connect,SplunkSinkTask,416,1134,58,84,68,260,48,56,3,30