--- old/src/java.base/share/classes/java/lang/ClassLoader.java	2019-10-06 15:46:27.313926780 +0300
+++ new/src/java.base/share/classes/java/lang/ClassLoader.java	2019-10-06 15:46:27.083926790 +0300
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2013, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016-2019, Azul Systems, Inc. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -2473,8 +2474,7 @@
                  *
                  * We use a static stack to hold the list of libraries we are
                  * loading because this can happen only when called by the
-                 * same thread because Runtime.load and Runtime.loadLibrary
-                 * are synchronous.
+                 * same thread because this block is synchronous.
                  *
                  * If there is a pending load operation for the library, we
                  * immediately return success; otherwise, we raise
@@ -2620,8 +2620,12 @@
         ClassLoader loader =
             (fromClass == null) ? null : fromClass.getClassLoader();
         if (sys_paths == null) {
-            usr_paths = initializePath("java.library.path");
-            sys_paths = initializePath("sun.boot.library.path");
+            synchronized (ClassLoader.class) {
+                if (sys_paths == null) {
+                    usr_paths = initializePath("java.library.path");
+                    sys_paths = initializePath("sun.boot.library.path");
+                }
+            }
         }
         if (isAbsolute) {
             if (loadLibrary0(fromClass, new File(name))) {