From affa2ee36c81c5146fbfea0f750c411c5350fe6a Mon Sep 17 00:00:00 2001
From: zeekling <lingzhaohui@zeekling.cn>
Date: Fri, 28 Jun 2024 21:27:15 +0800
Subject: [PATCH] =?UTF-8?q?=E5=A2=9E=E5=8A=A0=E6=B3=A8=E9=87=8A?=
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---
 .../src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java  | 1 +
 .../hadoop/hdfs/server/blockmanagement/DatanodeManager.java  | 5 ++++-
 .../apache/hadoop/hdfs/server/namenode/FSImageFormat.java    | 1 +
 .../hadoop/hdfs/server/namenode/FSImageFormatProtobuf.java   | 2 ++
 4 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
index e3f4bfcde8..8063d74518 100755
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
@@ -1121,6 +1121,7 @@ public class DFSConfigKeys extends CommonConfigurationKeys {
       DFS_SHORT_CIRCUIT_SHARED_MEMORY_WATCHER_INTERRUPT_CHECK_MS_DEFAULT =
       HdfsClientConfigKeys
           .DFS_SHORT_CIRCUIT_SHARED_MEMORY_WATCHER_INTERRUPT_CHECK_MS_DEFAULT;
+  // namenode 启动的keytab
   public static final String  DFS_NAMENODE_KEYTAB_FILE_KEY = "dfs.namenode.keytab.file";
   public static final String  DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY =
       HdfsClientConfigKeys.DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY;
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeManager.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeManager.java
index 07381fc696..4ff2987786 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeManager.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeManager.java
@@ -1772,7 +1772,10 @@ private void addCacheCommands(String blockPoolId, DatanodeDescriptor nodeinfo,
     }
   }
 
-  /** Handle heartbeat from datanodes. */
+  /** 
+   * Handle heartbeat from datanodes.
+   * 万恶的heartbeat，啥都干。。。
+   * */
   public DatanodeCommand[] handleHeartbeat(DatanodeRegistration nodeReg,
       StorageReport[] reports, final String blockPoolId,
       long cacheCapacity, long cacheUsed, int xceiverCount, 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImageFormat.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImageFormat.java
index 478cec55d0..5441fc3706 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImageFormat.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImageFormat.java
@@ -225,6 +225,7 @@ public void load(File file, boolean requireSameLayoutVersion)
           FSImageFormatProtobuf.Loader loader = new FSImageFormatProtobuf.Loader(
               conf, fsn, requireSameLayoutVersion);
           impl = loader;
+		  // 开始加载fsimage
           loader.load(file);
         } else {
           Loader loader = new Loader(conf, fsn);
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImageFormatProtobuf.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImageFormatProtobuf.java
index 183449f574..d084b10bd9 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImageFormatProtobuf.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImageFormatProtobuf.java
@@ -360,6 +360,7 @@ private void loadInternal(RandomAccessFile raFile, FileInputStream fin)
       if (!FSImageUtil.checkFileFormat(raFile)) {
         throw new IOException("Unrecognized file format");
       }
+	  // 加载summary
       FileSummary summary = FSImageUtil.loadSummary(raFile);
       if (requireSameLayoutVersion && summary.getLayoutVersion() !=
           HdfsServerConstants.NAMENODE_LAYOUT_VERSION) {
@@ -399,6 +400,7 @@ public int compare(FileSummary.Section s1, FileSummary.Section s2) {
        * a particular step to be started for once.
        */
       Step currentStep = null;
+	  // 是否开启并发加载
       boolean loadInParallel = enableParallelSaveAndLoad(conf);
 
       ExecutorService executorService = null;