1 files changed, 10 insertions, 15 deletions
diff --git a/test/2042-reference-processing/src/Main.java b/test/2042-reference-processing/src/Main.java
index ed670523ea..c7f547fe15 100644
--- a/test/2042-reference-processing/src/Main.java
+++ b/test/2042-reference-processing/src/Main.java
@@ -21,7 +21,7 @@ import java.lang.ref.WeakReference;
 import java.math.BigInteger;
 import java.util.concurrent.ArrayBlockingQueue;
 import java.util.concurrent.atomic.AtomicInteger;
-import java.util.HashMap;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.TreeMap;
 
 /**
@@ -48,7 +48,6 @@ public class Main {
     static volatile boolean pleaseStop;
 
     AtomicInteger totalFinalized = new AtomicInteger(0);
-    Object phantomRefsLock = new Object();
     int maxDropped = 0;
     int liveObjects = 0;
 
@@ -66,7 +65,7 @@ public class Main {
     // Maps from object number to Reference; Cleared references are deleted when queues are
     // processed.
     TreeMap<Integer, MyWeakReference> weakRefs = new TreeMap<>();
-    HashMap<Integer, MyPhantomReference> phantomRefs = new HashMap<>();
+    ConcurrentHashMap<Integer, MyPhantomReference> phantomRefs = new ConcurrentHashMap<>();
 
     class FinalizableObject {
         int n;
@@ -101,16 +100,14 @@ public class Main {
         }
     }
     boolean inPhantomRefs(int n) {
-        synchronized(phantomRefsLock) {
-            MyPhantomReference ref = phantomRefs.get(n);
-            if (ref == null) {
-                return false;
-            }
-            if (ref.n != n) {
-                System.out.println("phantomRef retrieval failed");
-            }
-            return true;
+        MyPhantomReference ref = phantomRefs.get(n);
+        if (ref == null) {
+            return false;
         }
+        if (ref.n != n) {
+            System.out.println("phantomRef retrieval failed");
+        }
+        return true;
     }
 
     void CheckOKToClearWeak(int num) {
@@ -197,9 +194,7 @@ public class Main {
             int me = nextAllocated++;
             listHead = new FinalizableObject(me, listHead);
             weakRefs.put(me, new MyWeakReference(listHead));
-            synchronized(phantomRefsLock) {
-                phantomRefs.put(me, new MyPhantomReference(listHead));
-            }
+            phantomRefs.put(me, new MyPhantomReference(listHead));
         }
         liveObjects += n;
     }