diff --git a/apm-commons/apm-datacarrier/src/main/java/org/apache/skywalking/apm/commons/datacarrier/DataCarrier.java b/apm-commons/apm-datacarrier/src/main/java/org/apache/skywalking/apm/commons/datacarrier/DataCarrier.java
index 4f5eabd60..daff12275 100644
--- a/apm-commons/apm-datacarrier/src/main/java/org/apache/skywalking/apm/commons/datacarrier/DataCarrier.java
+++ b/apm-commons/apm-datacarrier/src/main/java/org/apache/skywalking/apm/commons/datacarrier/DataCarrier.java
@@ -31,6 +31,10 @@ import org.apache.skywalking.apm.commons.datacarrier.partition.SimpleRollingPart
 /**
  * DataCarrier main class. use this instance to set Producer/Consumer Model.
  */
+
+/**
+ * 数据缓冲层
+ */
 public class DataCarrier<T> {
     private Channels<T> channels;
     private IDriver driver;
@@ -50,8 +54,11 @@ public class DataCarrier<T> {
 
     public DataCarrier(String name, String envPrefix, int channelSize, int bufferSize, BufferStrategy strategy) {
         this.name = name;
+        // 每个分区的内存大小
         bufferSize = EnvUtil.getInt(envPrefix + "_BUFFER_SIZE", bufferSize);
+        // 缓存的数据分区,提高并发度
         channelSize = EnvUtil.getInt(envPrefix + "_CHANNEL_SIZE", channelSize);
+        // 数据分区
         channels = new Channels<>(channelSize, bufferSize, new SimpleRollingPartitioner<T>(), strategy);
     }
 
@@ -126,6 +133,7 @@ public class DataCarrier<T> {
         if (driver != null) {
             driver.close(channels);
         }
+        // 创建数据采集线程
         driver = new ConsumeDriver<T>(this.name, this.channels, consumer, num, consumeCycle);
         driver.begin(channels);
         return this;
diff --git a/apm-commons/apm-datacarrier/src/main/java/org/apache/skywalking/apm/commons/datacarrier/buffer/Channels.java b/apm-commons/apm-datacarrier/src/main/java/org/apache/skywalking/apm/commons/datacarrier/buffer/Channels.java
index b9ad4fd77..5f7137e7e 100644
--- a/apm-commons/apm-datacarrier/src/main/java/org/apache/skywalking/apm/commons/datacarrier/buffer/Channels.java
+++ b/apm-commons/apm-datacarrier/src/main/java/org/apache/skywalking/apm/commons/datacarrier/buffer/Channels.java
@@ -33,6 +33,7 @@ public class Channels<T> {
     public Channels(int channelSize, int bufferSize, IDataPartitioner<T> partitioner, BufferStrategy strategy) {
         this.dataPartitioner = partitioner;
         this.strategy = strategy;
+        // 数据分区
         bufferChannels = new QueueBuffer[channelSize];
         for (int i = 0; i < channelSize; i++) {
             if (BufferStrategy.BLOCKING.equals(strategy)) {
diff --git a/apm-commons/apm-datacarrier/src/main/java/org/apache/skywalking/apm/commons/datacarrier/consumer/ConsumerThread.java b/apm-commons/apm-datacarrier/src/main/java/org/apache/skywalking/apm/commons/datacarrier/consumer/ConsumerThread.java
index 6c8d5ed80..2986205f6 100644
--- a/apm-commons/apm-datacarrier/src/main/java/org/apache/skywalking/apm/commons/datacarrier/consumer/ConsumerThread.java
+++ b/apm-commons/apm-datacarrier/src/main/java/org/apache/skywalking/apm/commons/datacarrier/consumer/ConsumerThread.java
@@ -50,6 +50,7 @@ public class ConsumerThread<T> extends Thread {
 
         final List<T> consumeList = new ArrayList<T>(1500);
         while (running) {
+            // 消费缓冲数据
             if (!consume(consumeList)) {
                 try {
                     Thread.sleep(consumeCycle);
@@ -67,11 +68,13 @@ public class ConsumerThread<T> extends Thread {
 
     private boolean consume(List<T> consumeList) {
         for (DataSource dataSource : dataSources) {
+            // 将数据读取到consumeList
             dataSource.obtain(consumeList);
         }
 
         if (!consumeList.isEmpty()) {
             try {
+                // 数据消费
                 consumer.consume(consumeList);
             } catch (Throwable t) {
                 consumer.onError(consumeList, t);
@@ -91,6 +94,9 @@ public class ConsumerThread<T> extends Thread {
     /**
      * DataSource is a reference to {@link Buffer}.
      */
+    /**
+     * 存储数据
+     */
     class DataSource {
         private QueueBuffer<T> sourceBuffer;
 
diff --git a/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/boot/ServiceManager.java b/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/boot/ServiceManager.java
index 015596ad2..a14dc1f56 100644
--- a/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/boot/ServiceManager.java
+++ b/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/boot/ServiceManager.java
@@ -62,6 +62,7 @@ public enum ServiceManager {
     private Map<Class, BootService> loadAllServices() {
         Map<Class, BootService> bootedServices = new LinkedHashMap<>();
         List<BootService> allServices = new LinkedList<>();
+        // 使用spi方式加载BootService
         load(allServices);
         for (final BootService bootService : allServices) {
             Class<? extends BootService> bootServiceClass = bootService.getClass();
diff --git a/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/context/TracingContext.java b/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/context/TracingContext.java
index cc1faa9af..cbfc687ba 100644
--- a/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/context/TracingContext.java
+++ b/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/context/TracingContext.java
@@ -467,6 +467,7 @@ public class TracingContext implements AbstractTracerContext {
                 }
                 AgentSo11y.measureTracingContextCompletion(false);
                 TraceSegment finishedSegment = segment.finish(limitMechanismWorking);
+                // 通知TraceSegmentServiceClient上报数据
                 TracingContext.ListenerManager.notifyFinish(finishedSegment);
                 running = false;
             }
diff --git a/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/context/trace/AbstractTracingSpan.java b/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/context/trace/AbstractTracingSpan.java
index 6c682ca41..8879f24ee 100644
--- a/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/context/trace/AbstractTracingSpan.java
+++ b/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/context/trace/AbstractTracingSpan.java
@@ -331,6 +331,9 @@ public abstract class AbstractTracingSpan implements AbstractSpan {
         return this;
     }
 
+    /**
+     * 异步存储span数据
+     */
     @Override
     public AbstractSpan asyncFinish() {
         if (!isInAsyncMode) {
diff --git a/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/jvm/JVMService.java b/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/jvm/JVMService.java
index ff6f6234e..8c4763bd2 100644
--- a/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/jvm/JVMService.java
+++ b/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/jvm/JVMService.java
@@ -42,6 +42,10 @@ import org.apache.skywalking.apm.util.RunnableWithExceptionProtection;
  * The <code>JVMService</code> represents a timer, which collectors JVM cpu, memory, memorypool, gc, thread and class info,
  * and send the collected info to Collector through the channel provided by {@link GRPCChannelManager}
  */
+
+/**
+ * 开始 JVM 指标收集
+ */
 @DefaultImplementor
 public class JVMService implements BootService, Runnable {
     private static final ILog LOGGER = LogManager.getLogger(JVMService.class);
diff --git a/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/remote/GRPCChannelManager.java b/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/remote/GRPCChannelManager.java
index 9744398fd..5cd4e8882 100755
--- a/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/remote/GRPCChannelManager.java
+++ b/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/remote/GRPCChannelManager.java
@@ -45,6 +45,9 @@ import org.apache.skywalking.apm.util.StringUtil;
 
 import static org.apache.skywalking.apm.agent.core.conf.Config.Collector.IS_RESOLVE_DNS_PERIODICALLY;
 
+/**
+ * 建立OAP的gRPC连接
+ */
 @DefaultImplementor
 public class GRPCChannelManager implements BootService, Runnable {
     private static final ILog LOGGER = LogManager.getLogger(GRPCChannelManager.class);
@@ -74,6 +77,7 @@ public class GRPCChannelManager implements BootService, Runnable {
         connectCheckFuture = Executors.newSingleThreadScheduledExecutor(
             new DefaultNamedThreadFactory("GRPCChannelManager")
         ).scheduleAtFixedRate(
+                // 心跳检查,skywalking通过随机选择一个oap节点并保持长连接的方式来代替负载均衡,如果连接不通重新选择一个节点
             new RunnableWithExceptionProtection(
                 this,
                 t -> LOGGER.error("unexpected exception.", t)
diff --git a/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/remote/ServiceManagementClient.java b/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/remote/ServiceManagementClient.java
index f1299559b..7ef4bb291 100755
--- a/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/remote/ServiceManagementClient.java
+++ b/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/remote/ServiceManagementClient.java
@@ -44,6 +44,9 @@ import org.apache.skywalking.apm.util.RunnableWithExceptionProtection;
 
 import static org.apache.skywalking.apm.agent.core.conf.Config.Collector.GRPC_UPSTREAM_TIMEOUT;
 
+/**
+ * 注册服务实例
+ */
 @DefaultImplementor
 public class ServiceManagementClient implements BootService, Runnable, GRPCChannelListener {
     private static final ILog LOGGER = LogManager.getLogger(ServiceManagementClient.class);
diff --git a/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/remote/TraceSegmentServiceClient.java b/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/remote/TraceSegmentServiceClient.java
index a0b86957f..3f5b60275 100644
--- a/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/remote/TraceSegmentServiceClient.java
+++ b/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/remote/TraceSegmentServiceClient.java
@@ -44,6 +44,9 @@ import static org.apache.skywalking.apm.agent.core.conf.Config.Buffer.BUFFER_SIZ
 import static org.apache.skywalking.apm.agent.core.conf.Config.Buffer.CHANNEL_SIZE;
 import static org.apache.skywalking.apm.agent.core.remote.GRPCChannelStatus.CONNECTED;
 
+/**
+ * 启动链路数据上报
+ */
 @DefaultImplementor
 public class TraceSegmentServiceClient implements BootService, IConsumer<TraceSegment>, TracingContextListener, GRPCChannelListener {
     private static final ILog LOGGER = LogManager.getLogger(TraceSegmentServiceClient.class);
@@ -179,6 +182,7 @@ public class TraceSegmentServiceClient implements BootService, IConsumer<TraceSe
 
     @Override
     public void statusChanged(GRPCChannelStatus status) {
+        // 当grpc连接成功后,创建上报数据的grpc客户端
         if (CONNECTED.equals(status)) {
             Channel channel = ServiceManager.INSTANCE.findService(GRPCChannelManager.class).getChannel();
             serviceStub = TraceSegmentReportServiceGrpc.newStub(channel);
diff --git a/skywalking源码.xmind b/skywalking源码.xmind
new file mode 100644
index 000000000..f0dedf7fe
Binary files /dev/null and b/skywalking源码.xmind differ