Flink: Empty implementation for pauseOrResumeSplits to prevent UnsupportedOperationException

flink/v1.18/flink/src/main/java/org/apache/iceberg/flink/source/reader/IcebergSourceSplitReader.java

@@ -20,7 +20,7 @@
 
 import java.io.IOException;
 import java.io.UncheckedIOException;
-import java.util.ArrayDeque;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 import java.util.Queue;
@@ -35,6 +35,7 @@
 import org.apache.iceberg.flink.source.split.SerializableComparator;
 import org.apache.iceberg.io.CloseableIterator;
 import org.apache.iceberg.relocated.com.google.common.collect.Lists;
+import org.apache.iceberg.relocated.com.google.common.collect.Queues;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -60,9 +61,18 @@ class IcebergSourceSplitReader<T> implements SplitReader<RecordAndPosition<T>, I
     this.openSplitFunction = openSplitFunction;
     this.splitComparator = splitComparator;
     this.indexOfSubtask = context.getIndexOfSubtask();
-    this.splits = new ArrayDeque<>();
+    this.splits = Queues.newArrayDeque();
   }
 
+  /**
+   * The method reads a batch of records from the assigned splits. If all the records from the
+   * current split are returned then it will emit a {@link ArrayBatchRecords#finishedSplit(String)}
+   * batch to signal this event. In the next fetch loop the reader will continue with the next split
+   * (if any).
+   *
+   * @return The fetched records
+   * @throws IOException If there is an error during reading
+   */
   @Override
   public RecordsWithSplitIds<RecordAndPosition<T>> fetch() throws IOException {
     metrics.incrementSplitReaderFetchCalls(1);
@@ -123,6 +133,16 @@ public void close() throws Exception {
     }
   }
 
+  @Override
+  public void pauseOrResumeSplits(
+      Collection<IcebergSourceSplit> splitsToPause, Collection<IcebergSourceSplit> splitsToResume) {
+    // IcebergSourceSplitReader only reads splits sequentially. When waiting for watermark alignment
+    // the SourceOperator will stop processing and recycling the fetched batches. This exhausts the
+    // {@link ArrayPoolDataIteratorBatcher#pool} and the `currentReader.next()` call will be
+    // blocked even without split-level watermark alignment. Based on this the
+    // `pauseOrResumeSplits` and the `wakeUp` are left empty.
+  }
+
   private long calculateBytes(IcebergSourceSplit split) {
     return split.task().files().stream().map(FileScanTask::length).reduce(0L, Long::sum);
   }

flink/v1.18/flink/src/test/java/org/apache/iceberg/flink/source/TestIcebergSourceWithWatermarkExtractor.java

@@ -40,7 +40,6 @@
 import org.apache.flink.api.common.eventtime.WatermarkStrategy;
 import org.apache.flink.api.common.typeinfo.TypeInformation;
 import org.apache.flink.configuration.Configuration;
-import org.apache.flink.configuration.PipelineOptions;
 import org.apache.flink.core.execution.JobClient;
 import org.apache.flink.metrics.Gauge;
 import org.apache.flink.runtime.metrics.MetricNames;
@@ -95,9 +94,7 @@ public class TestIcebergSourceWithWatermarkExtractor implements Serializable {
               .setNumberTaskManagers(1)
               .setNumberSlotsPerTaskManager(PARALLELISM)
               .setRpcServiceSharing(RpcServiceSharing.DEDICATED)
-              .setConfiguration(
-                  reporter.addToConfiguration(
-                      new Configuration().set(PipelineOptions.ALLOW_UNALIGNED_SOURCE_SPLITS, true)))
+              .setConfiguration(reporter.addToConfiguration(new Configuration()))
               .withHaLeadershipControl()
               .build());
 
@@ -383,7 +380,7 @@ protected IcebergSource<RowData> source() {
         .project(TestFixtures.TS_SCHEMA)
         .splitSize(100L)
         .streaming(true)
-        .monitorInterval(Duration.ofMillis(2))
+        .monitorInterval(Duration.ofMillis(10))
         .streamingStartingStrategy(StreamingStartingStrategy.TABLE_SCAN_THEN_INCREMENTAL)
         .build();
   }