HDFS-17339:Skip cacheReport when one blockPool does not have CacheBlock on this DataNode

Author: freedom

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BPServiceActor.java

@@ -514,6 +514,10 @@ DatanodeCommand cacheReport() throws IOException {
 
       String bpid = bpos.getBlockPoolId();
       List<Long> blockIds = dn.getFSDataset().getCacheReport(bpid);
+      // Skip cache report
+      if (blockIds.isEmpty()) {
+        return null;
+      }
       long createTime = monotonicNow();
 
       cmd = bpNamenode.cacheReport(bpRegistration, bpid, blockIds);