8205547: FileChannel/CleanerTest.java fails due to expected FD count

Reviewed-by: psandoz

test/jdk/java/nio/channels/FileChannel/CleanerTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2017, 2018, Oracle and/or its affiliates. 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
@@ -25,7 +25,9 @@
  * @bug 8147615
  * @summary Test whether an unreferenced FileChannel is actually cleaned
  * @requires (os.family == "linux") | (os.family == "mac") | (os.family == "solaris") | (os.family == "aix")
- * @modules java.management
+ * @library /test/lib
+ * @build jdk.test.lib.util.FileUtils CleanerTest
+ * @modules java.management java.base/sun.nio.ch:+open
  * @run main/othervm CleanerTest
  */
 
@@ -35,11 +37,19 @@ import java.lang.management.OperatingSystemMXBean;
 import java.lang.ref.PhantomReference;
 import java.lang.ref.Reference;
 import java.lang.ref.ReferenceQueue;
+import java.lang.ref.PhantomReference;
+import java.lang.ref.WeakReference;
+import java.lang.reflect.Field;
 import java.nio.channels.FileChannel;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.nio.file.StandardOpenOption;
+import java.util.HashSet;
+
+import jdk.test.lib.util.FileUtils;
+
+import sun.nio.ch.FileChannelImpl;
 
 public class CleanerTest {
     public static void main(String[] args) throws Throwable {
@@ -53,32 +63,64 @@ public class CleanerTest {
             return;
         }
 
+        FileUtils.listFileDescriptors(System.out);
+        long fdCount0 = unixMxBean.getOpenFileDescriptorCount();
+
         Path path = Paths.get(System.getProperty("test.dir", "."), "junk");
         try {
             FileChannel fc = FileChannel.open(path, StandardOpenOption.CREATE,
                 StandardOpenOption.READ, StandardOpenOption.WRITE);
 
-            ReferenceQueue refQueue = new ReferenceQueue();
-            Reference fcRef = new PhantomReference(fc, refQueue);
+            // Prepare to wait for Channel, FD and Cleaner to be reclaimed
+            ReferenceQueue<Object> refQueue = new ReferenceQueue<>();
+            HashSet<Reference<?>> pending = new HashSet<>();
 
-            long fdCount0 = unixMxBean.getOpenFileDescriptorCount();
-            fc = null;
+            Reference<Object> fcRef = new PhantomReference<>(fc, refQueue);
+            pending.add(fcRef);
 
-            // Perform repeated GCs until the reference has been enqueued.
-            do {
-                Thread.sleep(1);
-                System.gc();
-            } while (refQueue.poll() == null);
+            Field fdField = FileChannelImpl.class.getDeclaredField("fd");
+            fdField.setAccessible(true);
+            Object fd = fdField.get(fc);        // get the fd from the channel
+            WeakReference<Object> fdWeak = new WeakReference<>(fd, refQueue);
+            pending.add(fdWeak);
 
-            // Loop until the open file descriptor count has been decremented.
-            while (unixMxBean.getOpenFileDescriptorCount() > fdCount0 - 1) {
-                Thread.sleep(1);
+            Field closerField = FileChannelImpl.class.getDeclaredField("closer");
+            closerField.setAccessible(true);
+            Object closer = closerField.get(fc);
+            System.out.printf("  cleanup: %s, fd: %s, cf: %s%n", fc, fd, closer);
+
+            if (closer != null) {
+                WeakReference<Object> closerWeak = new WeakReference<>(closer, refQueue);
+                pending.add(closerWeak);
+                System.out.printf("    closerWeak: %s%n", closerWeak);
             }
 
+            // Wait for all of the objects being tracked to be reclaimed;
+            // The test will timeout if they are not reclaimed within the jtreg timeout
+            Reference<?> r;
+            while (((r = refQueue.remove(1000L)) != null)
+                    || !pending.isEmpty()) {
+                System.out.printf("    r: %s, pending: %d%n", r, pending.size());
+                if (r != null) {
+                    pending.remove(r);
+                } else {
+                    fc = null;
+                    fd = null;
+                    closer = null;
+                    System.gc();  // attempt to reclaim them
+                }
+            }
+
+            Reference.reachabilityFence(fc);
+            Reference.reachabilityFence(fd);
+            Reference.reachabilityFence(closer);
+
             long fdCount = unixMxBean.getOpenFileDescriptorCount();
-            if (fdCount != fdCount0 - 1) {
-                throw new RuntimeException("FD count expected " +
-                    (fdCount0 - 1) + "; actual " + fdCount);
+            if (fdCount != fdCount0) {
+                // Add debugging info about file descriptor changes
+                System.out.printf("initial count of open file descriptors: %d%n", fdCount0);
+                System.out.printf("final count of open file descriptors: %d%n", fdCount);
+                FileUtils.listFileDescriptors(System.out);
             }
         } finally {
             Files.delete(path);