--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/java/net/httpclient/ReferenceTracker.java	Tue Apr 17 08:54:17 2018 -0700
@@ -0,0 +1,130 @@
+/*
+ * Copyright (c) 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import jdk.internal.net.http.common.OperationTrackers;
+import jdk.internal.net.http.common.OperationTrackers.Tracker;
+
+import java.net.http.HttpClient;
+import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.stream.Collectors;
+
+/**
+ * A small helper class to help track clients which still
+ * have pending operations at the end of a test.
+ */
+public class ReferenceTracker {
+    private final ConcurrentLinkedQueue<Tracker> TRACKERS
+            = new ConcurrentLinkedQueue<Tracker>();
+
+    public static final ReferenceTracker INSTANCE
+            = new ReferenceTracker();
+
+    public HttpClient track(HttpClient client) {
+        Tracker tracker = OperationTrackers.getTracker(client);
+        assert tracker != null;
+        TRACKERS.add(tracker);
+        return client;
+    }
+
+    public long getTrackedClientCount() {
+        return TRACKERS.size();
+    }
+
+    public StringBuilder diagnose(StringBuilder warnings) {
+        for (Tracker tracker : TRACKERS) {
+            checkOutstandingOperations(warnings, tracker);
+        }
+        return warnings;
+    }
+
+    public boolean hasOutstandingOperations() {
+        return TRACKERS.stream().anyMatch(t -> t.getOutstandingOperations() > 0);
+    }
+
+    public long getOutstandingOperationsCount() {
+        return TRACKERS.stream()
+                .map(Tracker::getOutstandingOperations)
+                .filter(n -> n > 0)
+                .collect(Collectors.summingLong(n -> n));
+    }
+
+    public long getOutstandingClientCount() {
+        return TRACKERS.stream()
+                .map(Tracker::getOutstandingOperations)
+                .filter(n -> n > 0)
+                .count();
+    }
+
+    public AssertionError check(long graceDelayMs) {
+        AssertionError fail = null;
+        if (hasOutstandingOperations()) {
+            try {
+                Thread.sleep(graceDelayMs);
+            } catch (InterruptedException x) {
+                // OK
+            }
+            StringBuilder warnings = diagnose(new StringBuilder());
+            addSummary(warnings);
+            if (hasOutstandingOperations()) {
+                fail = new AssertionError(warnings.toString());
+            }
+        } else {
+            System.out.println("PASSED: No outstanding operations found in "
+                    + getTrackedClientCount() + " clients");
+        }
+        return fail;
+    }
+
+    private void addSummary(StringBuilder warning) {
+        long activeClients = getOutstandingClientCount();
+        long operations = getOutstandingOperationsCount();
+        long tracked = getTrackedClientCount();
+        if (warning.length() > 0) warning.append("\n");
+        int pos = warning.length();
+        warning.append("Found ")
+                .append(activeClients)
+                .append(" client still active, with ")
+                .append(operations)
+                .append(" operations still pending out of ")
+                .append(tracked)
+                .append(" tracked clients.");
+        System.out.println(warning.toString().substring(pos));
+        System.err.println(warning.toString().substring(pos));
+    }
+
+    private static void checkOutstandingOperations(StringBuilder warning, Tracker tracker) {
+        if (tracker.getOutstandingOperations() > 0) {
+            if (warning.length() > 0) warning.append("\n");
+            int pos = warning.length();
+            warning.append("WARNING: tracker for " + tracker.getName() + " has outstanding operations:");
+            warning.append("\n\tPending HTTP/1.1 operations: " + tracker.getOutstandingHttpOperations());
+            warning.append("\n\tPending HTTP/2 streams: " + tracker.getOutstandingHttp2Streams());
+            warning.append("\n\tPending WebSocket operations: " + tracker.getOutstandingWebSocketOperations());
+            warning.append("\n\tTotal pending operations: " + tracker.getOutstandingOperations());
+            warning.append("\n\tFacade referenced: " + tracker.isFacadeReferenced());
+            System.out.println(warning.toString().substring(pos));
+            System.err.println(warning.toString().substring(pos));
+        }
+    }
+
+}