From 538fe6c175174059ae380de8ae6820d179c0b7bf Mon Sep 17 00:00:00 2001
From: Dmitry Kropachev <dmitry.kropachev@gmail.com>
Date: Mon, 27 Jan 2025 07:39:15 -0400
Subject: [PATCH] TokenAwarePolicy: fix bad perf of ReplicaOrdering.RANDOM
 (#427)

`ReplicaOrdering.RANDOM` shows up to `20%` worse throughput.
Switching from `java.util.Random `to `ThreadLocalRandom` showed `20%`
improvement.
---
 .../com/datastax/driver/core/policies/TokenAwarePolicy.java    | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/driver-core/src/main/java/com/datastax/driver/core/policies/TokenAwarePolicy.java b/driver-core/src/main/java/com/datastax/driver/core/policies/TokenAwarePolicy.java
index 6f4c8d6c545..98323b58a65 100644
--- a/driver-core/src/main/java/com/datastax/driver/core/policies/TokenAwarePolicy.java
+++ b/driver-core/src/main/java/com/datastax/driver/core/policies/TokenAwarePolicy.java
@@ -40,6 +40,7 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.Set;
+import java.util.concurrent.ThreadLocalRandom;
 
 /**
  * A wrapper load balancing policy that adds token awareness to a child policy.
@@ -250,7 +251,7 @@ protected Host computeNext() {
 
       if (replicaOrdering == ReplicaOrdering.RANDOM) {
         List<Host> replicasList = Lists.newArrayList(replicas);
-        Collections.shuffle(replicasList);
+        Collections.shuffle(replicasList, ThreadLocalRandom.current());
         replicasIterator = replicasList.iterator();
       } else {
         replicasIterator = replicas.iterator();