diff --git a/client-spark/common/src/main/java/org/apache/spark/shuffle/writer/DataPusher.java b/client-spark/common/src/main/java/org/apache/spark/shuffle/writer/DataPusher.java
index 353006cc75..ca03a784bb 100644
--- a/client-spark/common/src/main/java/org/apache/spark/shuffle/writer/DataPusher.java
+++ b/client-spark/common/src/main/java/org/apache/spark/shuffle/writer/DataPusher.java
@@ -37,8 +37,13 @@
 import org.apache.uniffle.client.api.ShuffleWriteClient;
 import org.apache.uniffle.client.response.SendShuffleDataResult;
 import org.apache.uniffle.common.ShuffleBlockInfo;
+import org.apache.uniffle.common.exception.RssException;
 import org.apache.uniffle.common.util.ThreadUtils;
 
+/**
+ * A {@link DataPusher} that is responsible for sending data to remote
+ * shuffle servers asynchronously.
+ */
 public class DataPusher implements Closeable {
   private static final Logger LOGGER = LoggerFactory.getLogger(DataPusher.class);
 
@@ -49,7 +54,7 @@ public class DataPusher implements Closeable {
   private final Map<String, Set<Long>> taskToSuccessBlockIds;
   // Must be thread safe
   private final Map<String, Set<Long>> taskToFailedBlockIds;
-  private String appId;
+  private String rssAppId;
   // Must be thread safe
   private final Set<String> failedTaskIds;
 
@@ -74,13 +79,15 @@ public DataPusher(ShuffleWriteClient shuffleWriteClient,
   }
 
   public CompletableFuture<Long> send(AddBlockEvent event) {
-    assert appId != null;
+    if (rssAppId == null) {
+      throw new RssException("RssAppId should be set.");
+    }
     return CompletableFuture.supplyAsync(() -> {
       String taskId = event.getTaskId();
       List<ShuffleBlockInfo> shuffleBlockInfoList = event.getShuffleDataInfoList();
       try {
         SendShuffleDataResult result = shuffleWriteClient.sendShuffleData(
-            appId,
+            rssAppId,
             shuffleBlockInfoList,
             () -> !isValidTask(taskId)
         );
@@ -113,8 +120,8 @@ public boolean isValidTask(String taskId) {
     return !failedTaskIds.contains(taskId);
   }
 
-  public void setAppId(String appId) {
-    this.appId = appId;
+  public void setRssAppId(String rssAppId) {
+    this.rssAppId = rssAppId;
   }
 
   @Override
diff --git a/client-spark/common/src/main/java/org/apache/spark/shuffle/writer/WriteBufferManager.java b/client-spark/common/src/main/java/org/apache/spark/shuffle/writer/WriteBufferManager.java
index 497832c0df..580fce699d 100644
--- a/client-spark/common/src/main/java/org/apache/spark/shuffle/writer/WriteBufferManager.java
+++ b/client-spark/common/src/main/java/org/apache/spark/shuffle/writer/WriteBufferManager.java
@@ -299,6 +299,7 @@ public List<AddBlockEvent> buildBlockEvents(List<ShuffleBlockInfo> shuffleBlockI
       if (totalSize > sendSizeLimit) {
         LOG.info("Build event with " + shuffleBlockInfosPerEvent.size()
             + " blocks and " + totalSize + " bytes");
+        // Use final temporary variables for closures
         final long _memoryUsed = memoryUsed;
         events.add(
             new AddBlockEvent(taskId, shuffleBlockInfosPerEvent, () -> freeAllocatedMemory(_memoryUsed))
@@ -311,6 +312,7 @@ public List<AddBlockEvent> buildBlockEvents(List<ShuffleBlockInfo> shuffleBlockI
     if (!shuffleBlockInfosPerEvent.isEmpty()) {
       LOG.info("Build event with " + shuffleBlockInfosPerEvent.size()
           + " blocks and " + totalSize + " bytes");
+      // Use final temporary variables for closures
       final long _memoryUsed = memoryUsed;
       events.add(
           new AddBlockEvent(taskId, shuffleBlockInfosPerEvent, () -> freeAllocatedMemory(_memoryUsed))
@@ -328,7 +330,8 @@ public long spill(long size, MemoryConsumer trigger) {
     try {
       allOfFutures.get(memorySpillTimeoutSec, TimeUnit.SECONDS);
     } catch (TimeoutException timeoutException) {
-      // ignore this.
+      // A best effort strategy to wait.
+      // If timeout exception occurs, the underlying tasks won't be cancelled.
     } finally {
       long releasedSize = futures.stream().filter(x -> x.isDone()).mapToLong(x -> {
         try {
diff --git a/client-spark/common/src/test/java/org/apache/spark/shuffle/writer/DataPusherTest.java b/client-spark/common/src/test/java/org/apache/spark/shuffle/writer/DataPusherTest.java
index d0cf759dd7..20711dc053 100644
--- a/client-spark/common/src/test/java/org/apache/spark/shuffle/writer/DataPusherTest.java
+++ b/client-spark/common/src/test/java/org/apache/spark/shuffle/writer/DataPusherTest.java
@@ -94,7 +94,7 @@ public void testSendData() throws ExecutionException, InterruptedException {
         1,
         2
     );
-    dataPusher.setAppId("testSendData_appId");
+    dataPusher.setRssAppId("testSendData_appId");
 
     // sync send
     AddBlockEvent event = new AddBlockEvent("taskId", Arrays.asList(
diff --git a/client-spark/common/src/test/java/org/apache/spark/shuffle/writer/WriteBufferManagerTest.java b/client-spark/common/src/test/java/org/apache/spark/shuffle/writer/WriteBufferManagerTest.java
index 1e9bc07b04..f7c6de3d74 100644
--- a/client-spark/common/src/test/java/org/apache/spark/shuffle/writer/WriteBufferManagerTest.java
+++ b/client-spark/common/src/test/java/org/apache/spark/shuffle/writer/WriteBufferManagerTest.java
@@ -249,10 +249,7 @@ public void spillTest() {
 
     // case1. all events are flushed within normal time.
     long releasedSize = spyManager.spill(1000, mock(WriteBufferManager.class));
-    assertEquals(
-        64,
-        releasedSize
-    );
+    assertEquals(64, releasedSize);
 
     // case2. partial events are not flushed within normal time.
     // when calling spill func, 2 events will be spilled.
@@ -272,10 +269,7 @@ public void spillTest() {
       return event.getShuffleDataInfoList().stream().mapToLong(x -> x.getFreeMemory()).sum();
     }));
     releasedSize = spyManager.spill(1000, mock(WriteBufferManager.class));
-    assertEquals(
-        32,
-        releasedSize
-    );
+    assertEquals(32, releasedSize);
     assertEquals(32, spyManager.getUsedBytes());
     Awaitility.await().timeout(3, TimeUnit.SECONDS).until(() -> spyManager.getUsedBytes() == 0);
   }
diff --git a/client-spark/spark3/src/main/java/org/apache/spark/shuffle/RssShuffleManager.java b/client-spark/spark3/src/main/java/org/apache/spark/shuffle/RssShuffleManager.java
index 1e8c8387cb..472240512b 100644
--- a/client-spark/spark3/src/main/java/org/apache/spark/shuffle/RssShuffleManager.java
+++ b/client-spark/spark3/src/main/java/org/apache/spark/shuffle/RssShuffleManager.java
@@ -265,7 +265,7 @@ public <K, V, C> ShuffleHandle registerShuffle(int shuffleId, ShuffleDependency<
 
     if (id.get() == null) {
       id.compareAndSet(null, SparkEnv.get().conf().getAppId() + "_" + uuid);
-      dataPusher.setAppId(id.get());
+      dataPusher.setRssAppId(id.get());
     }
     LOG.info("Generate application id used in rss: " + id.get());