From a254d20e0e5ec936f6bf7ebee4a86322094db247 Mon Sep 17 00:00:00 2001
From: Joel Dice <joel.dice@gmail.com>
Date: Tue, 14 Feb 2012 13:01:00 -0700
Subject: [PATCH] improve seed generation in java.util.Random

The previous code caused frequent seed collisions for successive calls
to the no-arg constructor, even for single threaded workloads.  This
patch should avoid such collisions in both single and multi-threaded
cases.
---
 classpath/java/util/Random.java | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/classpath/java/util/Random.java b/classpath/java/util/Random.java
index 856f30424a..311230f538 100644
--- a/classpath/java/util/Random.java
+++ b/classpath/java/util/Random.java
@@ -13,7 +13,9 @@ package java.util;
 public class Random {
   private static final long Mask = 0x5DEECE66DL;
 
-  private static long nextSeed = 0;
+  private static final long InitialSeed = 123456789987654321L;
+
+  private static long nextSeed = InitialSeed;
 
   private long seed;
 
@@ -22,7 +24,13 @@ public class Random {
   }
 
   public Random() {
-    setSeed((nextSeed++) ^ System.currentTimeMillis());
+    synchronized (Random.class) {
+      setSeed(nextSeed ^ System.currentTimeMillis());
+      nextSeed *= 123456789987654321L;
+      if (nextSeed == 0) {
+        nextSeed = InitialSeed;
+      }
+    }
   }
 
   public void setSeed(long seed) {