Compulsorily close coordinator if task is stopped by the connect framework.

kafka-connect/kafka-connect/src/main/java/org/apache/iceberg/connect/IcebergSinkTask.java

@@ -19,6 +19,7 @@
 package org.apache.iceberg.connect;
 
 import java.util.Collection;
+import java.util.List;
 import java.util.Map;
 import org.apache.iceberg.catalog.Catalog;
 import org.apache.iceberg.relocated.com.google.common.collect.ImmutableMap;
@@ -61,7 +62,7 @@ public void close(Collection<TopicPartition> partitions) {
 
   private void close() {
     if (committer != null) {
-      committer.close(context.assignment());
+      committer.close(List.of());
       committer = null;
     }
 

kafka-connect/kafka-connect/src/main/java/org/apache/iceberg/connect/channel/CommitterImpl.java

@@ -136,19 +136,32 @@ public void stop() {
 
   @Override
   public void close(Collection<TopicPartition> closedPartitions) {
+    // Always try to stop the worker to avoid duplicates.
+    stopWorker();
+
+    // Defensive: close called without prior initialization (should not happen).
     if (!isInitialized.get()) {
-      LOG.warn("Unexpected close() call without resource initialization");
+      LOG.warn("Close unexpectedly called without partition assignment");
+      return;
+    }
+
+    // Empty partitions → task was stopped explicitly. Stop coordinator if running.
+    if (closedPartitions.isEmpty()) {
+      LOG.info("Task stopped. Closing coordinator.");
+      stopCoordinator();
       return;
     }
+
+    // Normal close: if leader partition is lost, stop coordinator.
     if (hasLeaderPartition(closedPartitions)) {
       LOG.info(
-          "Committer {}-{} lost leader partition. Stopping Coordinator.",
+          "Committer {}-{} lost leader partition. Stopping coordinator.",
           config.connectorName(),
           config.taskId());
       stopCoordinator();
     }
-    LOG.info("Stopping worker {}-{}.", config.connectorName(), config.taskId());
-    stopWorker();
+
+    // Reset offsets to last committed to avoid data loss.
     LOG.info(
         "Seeking to last committed offsets for worker {}-{}.",
         config.connectorName(),
@@ -167,7 +180,10 @@ public void save(Collection<SinkRecord> sinkRecords) {
 
   private void processControlEvents() {
     if (coordinatorThread != null && coordinatorThread.isTerminated()) {
-      throw new NotRunningException("Coordinator unexpectedly terminated");
+      throw new NotRunningException(
+          String.format(
+              "Coordinator unexpectedly terminated on committer %s-%s",
+              config.connectorName(), config.taskId()));
     }
     if (worker != null) {
       worker.process();
@@ -176,7 +192,7 @@ private void processControlEvents() {
 
   private void startWorker() {
     if (null == this.worker) {
-      LOG.info("Starting commit worker");
+      LOG.info("Starting commit worker {}-{}", config.connectorName(), config.taskId());
       SinkWriter sinkWriter = new SinkWriter(catalog, config);
       worker = new Worker(config, clientFactory, sinkWriter, context);
       worker.start();
@@ -185,7 +201,10 @@ private void startWorker() {
 
   private void startCoordinator() {
     if (null == this.coordinatorThread) {
-      LOG.info("Task elected leader, starting commit coordinator");
+      LOG.info(
+          "Task {}-{} elected leader, starting commit coordinator",
+          config.connectorName(),
+          config.taskId());
       Coordinator coordinator =
           new Coordinator(catalog, config, membersWhenWorkerIsCoordinator, clientFactory, context);
       coordinatorThread = new CoordinatorThread(coordinator);

kafka-connect/kafka-connect/src/main/java/org/apache/iceberg/connect/channel/Coordinator.java

@@ -75,6 +75,7 @@ class Coordinator extends Channel {
   private final String snapshotOffsetsProp;
   private final ExecutorService exec;
   private final CommitState commitState;
+  private volatile boolean terminated;
 
   Coordinator(
       Catalog catalog,
@@ -232,6 +233,10 @@ private void commitToTable(
             .filter(distinctByKey(ContentFile::location))
             .collect(Collectors.toList());
 
+    if (terminated) {
+      throw new ConnectException("Coordinator is terminated, commit aborted");
+    }
+
     if (dataFiles.isEmpty() && deleteFiles.isEmpty()) {
       LOG.info("Nothing to commit to table {}, skipping", tableIdentifier);
     } else {
@@ -311,7 +316,10 @@ private Map<Integer, Long> lastCommittedOffsetsForTable(Table table, String bran
   }
 
   void terminate() {
+    this.terminated = true;
+
     exec.shutdownNow();
+
     // wait for coordinator termination, else cause the sink task to fail
     try {
       if (!exec.awaitTermination(1, TimeUnit.MINUTES)) {
@@ -321,10 +329,4 @@ void terminate() {
       throw new ConnectException("Interrupted while waiting for coordinator shutdown", e);
     }
   }
-
-  @Override
-  public void stop() {
-    terminate();
-    super.stop();
-  }
 }

kafka-connect/kafka-connect/src/main/java/org/apache/iceberg/connect/channel/CoordinatorThread.java

@@ -64,5 +64,6 @@ boolean isTerminated() {
 
   void terminate() {
     this.terminated = true;
+    coordinator.terminate();
   }
 }