[FLINK-23864][connector/pulsar] Release Pulsar Message if user enable poolMessage option.
diff --git a/flink-connectors/flink-connector-pulsar/src/main/java/org/apache/flink/connector/pulsar/source/reader/split/PulsarOrderedPartitionSplitReader.java b/flink-connectors/flink-connector-pulsar/src/main/java/org/apache/flink/connector/pulsar/source/reader/split/PulsarOrderedPartitionSplitReader.java
index ac1821b..af650ea 100644
--- a/flink-connectors/flink-connector-pulsar/src/main/java/org/apache/flink/connector/pulsar/source/reader/split/PulsarOrderedPartitionSplitReader.java
+++ b/flink-connectors/flink-connector-pulsar/src/main/java/org/apache/flink/connector/pulsar/source/reader/split/PulsarOrderedPartitionSplitReader.java
@@ -74,6 +74,9 @@
     protected void finishedPollMessage(Message<byte[]> message) {
         // Nothing to do here.
         LOG.debug("Finished polling message {}", message);
+
+        // Release message
+        message.release();
     }
 
     @Override
diff --git a/flink-connectors/flink-connector-pulsar/src/main/java/org/apache/flink/connector/pulsar/source/reader/split/PulsarUnorderedPartitionSplitReader.java b/flink-connectors/flink-connector-pulsar/src/main/java/org/apache/flink/connector/pulsar/source/reader/split/PulsarUnorderedPartitionSplitReader.java
index efa383f..9c8e3d7 100644
--- a/flink-connectors/flink-connector-pulsar/src/main/java/org/apache/flink/connector/pulsar/source/reader/split/PulsarUnorderedPartitionSplitReader.java
+++ b/flink-connectors/flink-connector-pulsar/src/main/java/org/apache/flink/connector/pulsar/source/reader/split/PulsarUnorderedPartitionSplitReader.java
@@ -118,6 +118,9 @@
         if (sourceConfiguration.isEnableAutoAcknowledgeMessage()) {
             sneakyClient(() -> pulsarConsumer.acknowledge(message));
         }
+
+        // Release message
+        message.release();
     }
 
     @Override