Timestamp in GlobalIdGenerator is implemented using ThreadLocalRandom (#6623)

apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/context/ids/GlobalIdGenerator.java

@@ -18,8 +18,9 @@
 
 package org.apache.skywalking.apm.agent.core.context.ids;
 
-import java.util.Random;
 import java.util.UUID;
+import java.util.concurrent.ThreadLocalRandom;
+
 import org.apache.skywalking.apm.util.StringUtil;
 
 public final class GlobalIdGenerator {
@@ -58,7 +59,6 @@ public final class GlobalIdGenerator {
         // Just for considering time-shift-back only.
         private long runRandomTimestamp;
         private int lastRandomValue;
-        private Random random;
 
         private IDContext(long lastTimestamp, short threadSeq) {
             this.lastTimestamp = lastTimestamp;
@@ -74,11 +74,8 @@ public final class GlobalIdGenerator {
 
             if (currentTimeMillis < lastTimestamp) {
                 // Just for considering time-shift-back by Ops or OS. @hanahmily 's suggestion.
-                if (random == null) {
-                    random = new Random();
-                }
                 if (runRandomTimestamp != currentTimeMillis) {
-                    lastRandomValue = random.nextInt();
+                    lastRandomValue = ThreadLocalRandom.current().nextInt();
                     runRandomTimestamp = currentTimeMillis;
                 }
                 return lastRandomValue;