--- a/src/java.base/share/classes/java/net/Socket.java	Tue Apr 09 12:02:23 2019 +0100
+++ b/src/java.base/share/classes/java/net/Socket.java	Sat Apr 13 07:22:55 2019 +0100
@@ -35,6 +35,7 @@
 import java.security.PrivilegedAction;
 import java.util.Set;
 import java.util.Collections;
+import java.util.concurrent.locks.ReentrantLock;
 
 /**
  * This class implements client sockets (also called just
@@ -62,7 +63,7 @@
     private boolean bound = false;
     private boolean connected = false;
     private boolean closed = false;
-    private Object closeLock = new Object();
+    private final ReentrantLock closeLock = new ReentrantLock();
     private boolean shutIn = false;
     private boolean shutOut = false;
 
@@ -1573,13 +1574,20 @@
      * @spec JSR-51
      * @see #isClosed
      */
-    public synchronized void close() throws IOException {
-        synchronized(closeLock) {
-            if (isClosed())
-                return;
-            if (created)
-                impl.close();
-            closed = true;
+    public void close() throws IOException {
+        closeLock.lock();
+        try {
+            if (!closed) {
+                try {
+                    SocketImpl impl = this.impl;
+                    if (impl != null)
+                        impl.close();
+                } finally {
+                    closed = true;
+                }
+            }
+        } finally {
+            closeLock.unlock();
         }
     }
 
@@ -1700,8 +1708,11 @@
      * @see #close
      */
     public boolean isClosed() {
-        synchronized(closeLock) {
+        closeLock.lock();
+        try {
             return closed;
+        } finally {
+            closeLock.unlock();
         }
     }