diff --git a/pulsar-broker/src/test/java/org/apache/pulsar/client/api/ClientDeduplicationTest.java b/pulsar-broker/src/test/java/org/apache/pulsar/client/api/ClientDeduplicationTest.java
index 168886f733a3c..d2f9617a5faae 100644
--- a/pulsar-broker/src/test/java/org/apache/pulsar/client/api/ClientDeduplicationTest.java
+++ b/pulsar-broker/src/test/java/org/apache/pulsar/client/api/ClientDeduplicationTest.java
@@ -27,6 +27,9 @@
 import java.util.Arrays;
 import java.util.List;
 import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
 import java.util.stream.Collectors;
 import lombok.extern.slf4j.Slf4j;
@@ -372,4 +375,51 @@ public void testKeyBasedBatchingOrder() throws Exception {
         consumer.close();
         producer.close();
     }
+
+    @Test
+    public void testUpdateSequenceIdInSyncCodeSegment() throws Exception {
+        final String topic = "persistent://my-property/my-ns/testUpdateSequenceIdInSyncCodeSegment";
+        int totalMessage = 200;
+        int threadSize = 5;
+        String topicName = "subscription";
+        ExecutorService executorService = Executors.newFixedThreadPool(threadSize);
+        conf.setBrokerDeduplicationEnabled(true);
+
+        //build producer/consumer
+        Producer<byte[]> producer = pulsarClient.newProducer()
+                .topic(topic)
+                .producerName("producer")
+                .sendTimeout(0, TimeUnit.SECONDS)
+                .create();
+
+        Consumer<byte[]> consumer = pulsarClient.newConsumer()
+                .topic(topic)
+                .subscriptionType(SubscriptionType.Exclusive)
+                .subscriptionName(topicName)
+                .subscribe();
+
+        CountDownLatch countDownLatch = new CountDownLatch(threadSize);
+        //Send messages in multiple-thread
+        for (int i = 0; i < threadSize; i++) {
+            executorService.submit(() -> {
+                try {
+                    for (int j = 0; j < totalMessage; j++) {
+                        //The message will be sent with out-of-order sequence ID.
+                        producer.newMessage().sendAsync();
+                    }
+                } catch (Exception e) {
+                    log.error("Failed to send/ack messages with transaction.", e);
+                } finally {
+                    countDownLatch.countDown();
+                }
+            });
+        }
+        //wait the all send op is executed and store its futures in the arraylist.
+        countDownLatch.await();
+
+        for (int i = 0; i < threadSize * totalMessage; i++) {
+            Message<byte[]> msg = consumer.receive(5, TimeUnit.SECONDS);
+            assertNotNull(msg);
+        }
+    }
 }
diff --git a/pulsar-client/src/main/java/org/apache/pulsar/client/impl/ProducerImpl.java b/pulsar-client/src/main/java/org/apache/pulsar/client/impl/ProducerImpl.java
index dceaf50214182..ef3ead790bc61 100644
--- a/pulsar-client/src/main/java/org/apache/pulsar/client/impl/ProducerImpl.java
+++ b/pulsar-client/src/main/java/org/apache/pulsar/client/impl/ProducerImpl.java
@@ -101,7 +101,7 @@ public class ProducerImpl<T> extends ProducerBase<T> implements TimerTask, Conne
     // Producer id, used to identify a producer within a single connection
     protected final long producerId;
 
-    // Variable is used through the atomic updater
+    // Variable is updated in a synchronized block
     private volatile long msgIdGenerator;
 
     private final OpSendMsgQueue pendingMessages;
@@ -169,10 +169,6 @@ public class ProducerImpl<T> extends ProducerBase<T> implements TimerTask, Conne
 
     private boolean errorState;
 
-    @SuppressWarnings("rawtypes")
-    private static final AtomicLongFieldUpdater<ProducerImpl> msgIdGeneratorUpdater = AtomicLongFieldUpdater
-            .newUpdater(ProducerImpl.class, "msgIdGenerator");
-
     public ProducerImpl(PulsarClientImpl client, String topic, ProducerConfigurationData conf,
                         CompletableFuture<Producer<T>> producerCreatedFuture, int partitionIndex, Schema<T> schema,
                         ProducerInterceptors interceptors, Optional<String> overrideProducerName) {
@@ -487,7 +483,7 @@ public void sendAsync(Message<?> message, SendCallback callback) {
 
         // Update the message metadata before computing the payload chunk size to avoid a large message cannot be split
         // into chunks.
-        final long sequenceId = updateMessageMetadata(msgMetadata, uncompressedSize);
+        updateMessageMetadata(msgMetadata, uncompressedSize);
 
         // send in chunks
         int totalChunks;
@@ -527,7 +523,6 @@ public void sendAsync(Message<?> message, SendCallback callback) {
 
         try {
             int readStartIndex = 0;
-            String uuid = totalChunks > 1 ? String.format("%s-%d", producerName, sequenceId) : null;
             ChunkedMessageCtx chunkedMessageCtx = totalChunks > 1 ? ChunkedMessageCtx.get(totalChunks) : null;
             byte[] schemaVersion = totalChunks > 1 && msg.getMessageBuilder().hasSchemaVersion()
                     ? msg.getMessageBuilder().getSchemaVersion() : null;
@@ -555,6 +550,11 @@ public void sendAsync(Message<?> message, SendCallback callback) {
                     return;
                 }
                 synchronized (this) {
+                    // Update the message metadata before computing the payload chunk size
+                    // to avoid a large message cannot be split into chunks.
+                    final long sequenceId = updateMessageMetadataSequenceId(msgMetadata);
+                    String uuid = totalChunks > 1 ? String.format("%s-%d", producerName, sequenceId) : null;
+
                     serializeAndSendMessage(msg, payload, sequenceId, uuid, chunkId, totalChunks,
                             readStartIndex, payloadChunkSize, compressedPayload, compressed,
                             compressedPayload.readableBytes(), callback, chunkedMessageCtx, messageId);
@@ -577,15 +577,7 @@ public void sendAsync(Message<?> message, SendCallback callback) {
      * @param uncompressedSize
      * @return the sequence id
      */
-    private long updateMessageMetadata(final MessageMetadata msgMetadata, final int uncompressedSize) {
-        final long sequenceId;
-        if (!msgMetadata.hasSequenceId()) {
-            sequenceId = msgIdGeneratorUpdater.getAndIncrement(this);
-            msgMetadata.setSequenceId(sequenceId);
-        } else {
-            sequenceId = msgMetadata.getSequenceId();
-        }
-
+    private void updateMessageMetadata(final MessageMetadata msgMetadata, final int uncompressedSize) {
         if (!msgMetadata.hasPublishTime()) {
             msgMetadata.setPublishTime(client.getClientClock().millis());
 
@@ -599,6 +591,16 @@ private long updateMessageMetadata(final MessageMetadata msgMetadata, final int
             }
             msgMetadata.setUncompressedSize(uncompressedSize);
         }
+    }
+
+    private long updateMessageMetadataSequenceId(final MessageMetadata msgMetadata) {
+        final long sequenceId;
+        if (!msgMetadata.hasSequenceId()) {
+            sequenceId = msgIdGenerator++;
+            msgMetadata.setSequenceId(sequenceId);
+        } else {
+            sequenceId = msgMetadata.getSequenceId();
+        }
         return sequenceId;
     }