diff --git a/apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/boot/DefaultNamedThreadFactory.java b/apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/boot/DefaultNamedThreadFactory.java
index 0d8252b51d63cda1f11d47bc4fea7c306f35452b..55395d810e524a7b6c774f7c8b5d0e4178a4524a 100644
--- a/apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/boot/DefaultNamedThreadFactory.java
+++ b/apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/boot/DefaultNamedThreadFactory.java
@@ -32,8 +32,7 @@ public class DefaultNamedThreadFactory implements ThreadFactory {
     }
     @Override
     public Thread newThread(Runnable r) {
-        Thread t = new Thread();
-        t.setName(namePrefix + threadSeq.getAndIncrement());
+        Thread t = new Thread(r,namePrefix + threadSeq.getAndIncrement());
         t.setDaemon(true);
         return t;
     }
diff --git a/apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/remote/AppAndServiceRegisterClient.java b/apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/remote/AppAndServiceRegisterClient.java
index 3378592b7aeb8599fd7cf2750dee162c3b3520d0..0149fceaa3dbbf2990f7c3e15229767e995a0d34 100644
--- a/apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/remote/AppAndServiceRegisterClient.java
+++ b/apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/remote/AppAndServiceRegisterClient.java
@@ -106,6 +106,7 @@ public class AppAndServiceRegisterClient implements BootService, GRPCChannelList
 
     @Override
     public void run() {
+        logger.debug("AppAndServiceRegisterClient running, status:{}.",status);
         boolean shouldTry = true;
         while (CONNECTED.equals(status) && shouldTry) {
             shouldTry = false;
diff --git a/apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/remote/GRPCChannelManager.java b/apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/remote/GRPCChannelManager.java
index 4e7fc4c817018640556fd85502020d49759b6e5f..8f5e264ef69b0237b153badb1451923074d4b41e 100644
--- a/apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/remote/GRPCChannelManager.java
+++ b/apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/remote/GRPCChannelManager.java
@@ -33,12 +33,11 @@ import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
 import org.skywalking.apm.agent.core.boot.BootService;
 import org.skywalking.apm.agent.core.boot.DefaultNamedThreadFactory;
+import org.skywalking.apm.agent.core.conf.Config;
 import org.skywalking.apm.agent.core.conf.RemoteDownstreamConfig;
 import org.skywalking.apm.logging.ILog;
 import org.skywalking.apm.logging.LogManager;
 
-import static org.skywalking.apm.agent.core.conf.Config.Collector.GRPC_CHANNEL_CHECK_INTERVAL;
-
 /**
  * @author wusheng
  */
@@ -60,7 +59,7 @@ public class GRPCChannelManager implements BootService, Runnable {
     public void boot() throws Throwable {
         connectCheckFuture = Executors
             .newSingleThreadScheduledExecutor(new DefaultNamedThreadFactory("GRPCChannelManager"))
-            .scheduleAtFixedRate(this, 0, GRPC_CHANNEL_CHECK_INTERVAL, TimeUnit.SECONDS);
+            .scheduleAtFixedRate(this, 0, Config.Collector.GRPC_CHANNEL_CHECK_INTERVAL, TimeUnit.SECONDS);
     }
 
     @Override
@@ -72,15 +71,18 @@ public class GRPCChannelManager implements BootService, Runnable {
     public void shutdown() throws Throwable {
         connectCheckFuture.cancel(true);
         managedChannel.shutdownNow();
+        logger.debug("Selected collector grpc service shutdown.");
     }
 
     @Override
     public void run() {
+        logger.debug("Selected collector grpc service running, reconnect:{}.",reconnect);
         if (reconnect) {
             if (RemoteDownstreamConfig.Collector.GRPC_SERVERS.size() > 0) {
-                int index = random.nextInt() % RemoteDownstreamConfig.Collector.GRPC_SERVERS.size();
-                String server = RemoteDownstreamConfig.Collector.GRPC_SERVERS.get(index);
+                String server = "";
                 try {
+                    int index = Math.abs(random.nextInt()) % RemoteDownstreamConfig.Collector.GRPC_SERVERS.size();
+                    server = RemoteDownstreamConfig.Collector.GRPC_SERVERS.get(index);
                     String[] ipAndPort = server.split(":");
                     ManagedChannelBuilder<?> channelBuilder =
                         NettyChannelBuilder.forAddress(ipAndPort[0], Integer.parseInt(ipAndPort[1]))
@@ -101,7 +103,7 @@ public class GRPCChannelManager implements BootService, Runnable {
                 }
             }
 
-            logger.debug("Selected collector grpc service is not available. Wait {} seconds to retry", GRPC_CHANNEL_CHECK_INTERVAL);
+            logger.debug("Selected collector grpc service is not available. Wait {} seconds to retry", Config.Collector.GRPC_CHANNEL_CHECK_INTERVAL);
         }
     }