--- old/test/jdk/java/lang/ClassLoader/nativeLibrary/NativeLibraryTest.java	2018-05-02 11:26:03.070069810 -0700
+++ new/test/jdk/java/lang/ClassLoader/nativeLibrary/NativeLibraryTest.java	2018-05-02 11:26:02.750069826 -0700
@@ -31,17 +31,49 @@
  */
 
 import java.io.IOException;
+import java.lang.ref.WeakReference;
 import java.net.MalformedURLException;
 import java.net.URL;
 import java.net.URLClassLoader;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+import java.util.function.BooleanSupplier;
 
 public class NativeLibraryTest {
     static final Path CLASSES = Paths.get("classes");
     static int unloadedCount = 0;
 
+    /** No guarantees, but effective in practice. */
+    static void forceFullGc() {
+        CountDownLatch finalizeDone = new CountDownLatch(1);
+        WeakReference<?> ref = new WeakReference<Object>(new Object() {
+            protected void finalize() { finalizeDone.countDown(); }});
+        try {
+            for (int i = 0; i < 10; i++) {
+                System.gc();
+                if (finalizeDone.await(1L, TimeUnit.SECONDS) && ref.get() == null) {
+                    System.runFinalization(); // try to pick up stragglers
+                    return;
+                }
+            }
+        } catch (InterruptedException unexpected) {
+            throw new AssertionError("unexpected InterruptedException");
+        }
+        throw new AssertionError("failed to do a \"full\" gc");
+    }
+
+    static void gcAwait(BooleanSupplier s) {
+        for (int i = 0; i < 10; i++) {
+            if (s.getAsBoolean())
+                return;
+            forceFullGc();
+        }
+        throw new AssertionError("failed to satisfy condition");
+    }
+
     /*
      * Called by JNI_OnUnload when the native library is unloaded
      */
@@ -52,19 +84,12 @@
     public static void main(String... args) throws Exception {
         setup();
 
-        for (int count=1; count <= 5; count++) {
+        for (int count = 1; count <= 5; count++) {
             // create a class loader and load a native library
             runTest();
-            // unloading the class loader and native library
-            System.gc();
-            // give Cleaner thread a chance to unload the native library
-            Thread.sleep(100);
-
-            // unloadedCount is incremented when the native library is unloaded
-            if (count != unloadedCount) {
-                throw new RuntimeException("Expected unloaded=" + count +
-                    " but got=" + unloadedCount);
-            }
+
+            final int finalCount = count;
+            gcAwait(() -> unloadedCount == finalCount);
         }
     }