Wait to rebalanced cluster until server booted.

Author: weixiang

oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/status/BootingStatus.java

@@ -18,6 +18,7 @@
 
 package org.apache.skywalking.oap.server.core.status;
 
+import java.util.concurrent.CountDownLatch;
 import lombok.AccessLevel;
 import lombok.Getter;
 import lombok.Setter;
@@ -28,6 +29,7 @@
 @Getter
 @Setter(AccessLevel.PACKAGE)
 public class BootingStatus {
+    private final CountDownLatch bootingLatch = new CountDownLatch(1);
     /**
      * The status of OAP is fully booted successfully.
      */
@@ -36,4 +38,13 @@ public class BootingStatus {
      * The uptime in milliseconds if {@link #isBooted} is true;
      */
     private long uptime = 0;
+
+    public void setBooted(final boolean booted) {
+        isBooted = booted;
+        bootingLatch.countDown();
+    }
+
+    public void waitUntilBooted() throws InterruptedException {
+        bootingLatch.await();
+    }
 }

oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/status/ServerStatusService.java

@@ -65,7 +65,11 @@ public void bootedNow(List<ApplicationConfiguration.ModuleConfiguration> configu
 
     public void rebalancedCluster(long rebalancedTime) {
         if (!bootingStatus.isBooted()) {
-            return;
+            try {
+                bootingStatus.waitUntilBooted();
+            } catch (InterruptedException e) {
+                // ignore
+            }
         }
 
         clusterStatus.setRebalancedTime(rebalancedTime);