ThreadLocalRandom is recommended over Random in multithreaded environments, try 2

2 files changed, 5 insertions, 7 deletions

diff --git a/vespa-http-client/src/main/java/com/yahoo/vespa/http/client/core/communication/GatewayThrottler.java b/vespa-http-client/src/main/java/com/yahoo/vespa/http/client/core/communication/GatewayThrottler.java
index cc637904553..189fd348c0e 100644
--- a/vespa-http-client/src/main/java/com/yahoo/vespa/http/client/core/communication/GatewayThrottler.java
+++ b/vespa-http-client/src/main/java/com/yahoo/vespa/http/client/core/communication/GatewayThrottler.java
@@ -1,7 +1,7 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.vespa.http.client.core.communication;
 
-import java.util.Random;
+import java.util.concurrent.ThreadLocalRandom;
 
 /**
  * When the gateways says it can not handle more load, we should send less load. That is the responsibility
@@ -13,7 +13,6 @@ public class GatewayThrottler {
 
     private long backOffTimeMs = 0;
     private final long maxSleepTimeMs;
-    private static Random random = new Random();
 
     public GatewayThrottler(long maxSleepTimeMs) {
         this.maxSleepTimeMs = maxSleepTimeMs;
@@ -39,7 +38,7 @@ public class GatewayThrottler {
     }
 
     public int distribute(int expected) {
-        double factor = 0.5 + random.nextDouble();
+        double factor = 0.5 + ThreadLocalRandom.current().nextDouble();
         Double result = expected * factor;
         return result.intValue();
     }
diff --git a/vespa-http-client/src/main/java/com/yahoo/vespa/http/client/core/operationProcessor/IncompleteResultsThrottler.java b/vespa-http-client/src/main/java/com/yahoo/vespa/http/client/core/operationProcessor/IncompleteResultsThrottler.java
index 6ecbb56888e..7cf4e32a880 100644
--- a/vespa-http-client/src/main/java/com/yahoo/vespa/http/client/core/operationProcessor/IncompleteResultsThrottler.java
+++ b/vespa-http-client/src/main/java/com/yahoo/vespa/http/client/core/operationProcessor/IncompleteResultsThrottler.java
@@ -3,7 +3,7 @@ package com.yahoo.vespa.http.client.core.operationProcessor;
 
 import com.yahoo.vespa.http.client.core.ThrottlePolicy;
 
-import java.util.Random;
+import java.util.concurrent.ThreadLocalRandom;
 
 /**
  * Adjusts in-flight operations based on throughput. It will walk the graph and try to find
@@ -34,11 +34,10 @@ public class IncompleteResultsThrottler {
     private final ConcurrentDocumentOperationBlocker blocker = new ConcurrentDocumentOperationBlocker();
     private final int maxInFlightValue;
     private final int minInFlightValue;
-    private final Random random = new Random();
     private final ThrottlePolicy policy;
 
     // 9-11 seconds with some randomness to avoid fully synchronous feeders.
-    public final long phaseSizeMs = 9000 + (random.nextInt() % 2000);
+    public final long phaseSizeMs = 9000 + (ThreadLocalRandom.current().nextInt() % 2000);
     private final Clock clock;
 
     private final Object monitor = new Object();
@@ -129,7 +128,7 @@ public class IncompleteResultsThrottler {
 
     private void adjustCycle() {
         adjustCycleCount++;
-        stabilizingPhasesLeft = adjustCycleCount < 5 ? 1 : 2 + random.nextInt() % 2;
+        stabilizingPhasesLeft = adjustCycleCount < 5 ? 1 : 2 + ThreadLocalRandom.current().nextInt() % 2;
 
         double maxPerformanceChange = getCeilingDifferencePerformance(adjustCycleCount);
         boolean messagesQueued = minPermitsAvailable < 2;