8289284: jdk.tracePinnedThreads output confusing when pinned due to native frame

Reviewed-by: jpai, mchung

make/test/JtregNativeJdk.gmk

@@ -77,6 +77,7 @@ ifeq ($(call isTargetOs, windows), true)
   BUILD_JDK_JTREG_LIBRARIES_LDFLAGS_libLinkerInvokerUnnamed := $(LIBCXX)
   BUILD_JDK_JTREG_LIBRARIES_LDFLAGS_libLinkerInvokerModule := $(LIBCXX)
   BUILD_JDK_JTREG_LIBRARIES_LDFLAGS_libLoaderLookupInvoker := $(LIBCXX)
+  BUILD_JDK_JTREG_LIBRARIES_LIBS_libTracePinnedThreads := jvm.lib
 else
   BUILD_JDK_JTREG_LIBRARIES_LIBS_libstringPlatformChars := -ljava
   BUILD_JDK_JTREG_LIBRARIES_LIBS_libDirectIO := -ljava
@@ -89,6 +90,7 @@ else
   BUILD_JDK_JTREG_LIBRARIES_LIBS_libExplicitAttach := -ljvm
   BUILD_JDK_JTREG_LIBRARIES_LDFLAGS_libExplicitAttach := -pthread
   BUILD_JDK_JTREG_LIBRARIES_LDFLAGS_libImplicitAttach := -pthread
+  BUILD_JDK_JTREG_LIBRARIES_LIBS_libTracePinnedThreads := -ljvm
   BUILD_JDK_JTREG_EXCLUDE += exerevokeall.c
   ifeq ($(call isTargetOs, linux), true)
     BUILD_JDK_JTREG_LIBRARIES_LIBS_libInheritedChannel := -ljava

src/java.base/share/classes/java/lang/PinnedThreadPrinter.java

@@ -86,7 +86,7 @@ class PinnedThreadPrinter {
     }
 
     /**
-     * Prints the stack trace of the current mounted vthread continuation.
+     * Prints the continuation stack trace.
      *
      * @param printAll true to print all stack frames, false to only print the
      *        frames that are native or holding a monitor
@@ -103,7 +103,7 @@ class PinnedThreadPrinter {
             .filter(f -> (f.isNativeMethod() || f.getMonitors().length > 0))
             .map(LiveStackFrame::getDeclaringClass)
             .findFirst()
-            .ifPresent(klass -> {
+            .ifPresentOrElse(klass -> {
                 int hash = hash(stack);
                 Hashes hashes = HASHES.get(klass);
                 synchronized (hashes) {
@@ -112,7 +112,7 @@ class PinnedThreadPrinter {
                         printStackTrace(stack, out, printAll);
                     }
                 }
-            });
+            }, () -> printStackTrace(stack, out, true));  // not found
     }
 
     private static void printStackTrace(List<LiveStackFrame> stack,
@@ -122,9 +122,9 @@ class PinnedThreadPrinter {
         for (LiveStackFrame frame : stack) {
             var ste = frame.toStackTraceElement();
             int monitorCount = frame.getMonitors().length;
-            if (monitorCount > 0 || frame.isNativeMethod()) {
+            if (monitorCount > 0) {
                 out.format("    %s <== monitors:%d%n", ste, monitorCount);
-            } else if (printAll) {
+            } else if (frame.isNativeMethod() || printAll) {
                 out.format("    %s%n", ste);
             }
         }

test/jdk/java/lang/Thread/virtual/TracePinnedThreads.java

@@ -23,11 +23,13 @@
 
 /**
  * @test
+ * @bug 8284161 8289284
  * @summary Basic test of debugging option to trace pinned threads
  * @requires vm.continuations
- * @compile --enable-preview -source ${jdk.version} TracePinnedThreads.java
+ * @enablePreview
- * @run main/othervm --enable-preview -Djdk.tracePinnedThreads=full TracePinnedThreads
+ * @library /test/lib
- * @run main/othervm --enable-preview -Djdk.tracePinnedThreads=short TracePinnedThreads
+ * @run testng/othervm -Djdk.tracePinnedThreads=full TracePinnedThreads
+ * @run testng/othervm -Djdk.tracePinnedThreads=short TracePinnedThreads
  */
 
 import java.io.ByteArrayOutputStream;
@@ -35,32 +37,81 @@ import java.io.PrintStream;
 import java.time.Duration;
 import java.util.concurrent.locks.LockSupport;
 
+import jdk.test.lib.thread.VThreadRunner;
+import org.testng.annotations.Test;
+import static org.testng.Assert.*;
+
 public class TracePinnedThreads {
     static final Object lock = new Object();
 
-    public static void main(String[] args) throws Exception {
+    /**
-        ByteArrayOutputStream baos = new ByteArrayOutputStream();
+     * Parks current thread for 1 second.
+     */
+    private static void park() {
+        long nanos = Duration.ofSeconds(1).toNanos();
+        LockSupport.parkNanos(nanos);
+    }
 
+    /**
+     * Invokes the park method through a native frame to park the current
+     * thread for 1 second.
+     */
+    private static native void invokePark();
+
+    /**
+     * Test parking inside synchronized block.
+     */
+    @Test
+    public void testPinnedCausedBySynchronizedBlock() throws Exception {
+        String output = run(() -> {
+            synchronized (lock) {
+                park();
+            }
+        });
+        assertContains(output, "<== monitors:1");
+        assertDoesNotContain(output, "(Native Method)");
+    }
+
+    /**
+     * Test parking with native frame on stack.
+     */
+    @Test
+    public void testPinnedCausedByNativeMethod() throws Exception {
+        System.loadLibrary("TracePinnedThreads");
+        String output = run(() -> invokePark());
+        assertContains(output, "(Native Method)");
+        assertDoesNotContain(output, "<== monitors");
+    }
+
+    /**
+     * Runs a task in a virutal thread, returning a String with any output printed
+     * to standard output.
+     */
+    private static String run(Runnable task) throws Exception {
+        ByteArrayOutputStream baos = new ByteArrayOutputStream();
         PrintStream original = System.out;
-        System.setOut(new PrintStream(baos));
+        System.setOut(new PrintStream(baos, true));
         try {
-            Thread.ofVirtual().start(() -> {
+            VThreadRunner.run(task::run);
-                synchronized (lock) {
-                    long nanos = Duration.ofSeconds(1).toNanos();
-                    LockSupport.parkNanos(nanos);
-                }
-            }).join();
-            System.out.flush();
         } finally {
             System.setOut(original);
         }
-
+        String output = new String(baos.toByteArray());
-        String output = new String(baos.toByteArray()); // default charset
         System.out.println(output);
+        return output;
+    }
 
-        String expected = "<== monitors:1";
+    /**
-        if (!output.contains(expected)) {
+     * Tests that s1 contains s2.
-            throw new RuntimeException("expected: \"" + expected + "\"");
+     */
-        }
+    private static void assertContains(String s1, String s2) {
+        assertTrue(s1.contains(s2), s2 + " not found!!!");
+    }
+
+    /**
+     * Tests that s1 does not contain s2.
+     */
+    private static void assertDoesNotContain(String s1, String s2) {
+        assertFalse(s1.contains(s2), s2 + " found!!");
     }
 }

test/jdk/java/lang/Thread/virtual/libTracePinnedThreads.c

@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) 2022, 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.
+ */
+
+#include "jni.h"
+
+JNIEXPORT void JNICALL Java_TracePinnedThreads_invokePark(JNIEnv *env, jclass clazz) {
+    jmethodID mid = (*env)->GetStaticMethodID(env, clazz, "park", "()V");
+    if (mid != NULL) {
+        (*env)->CallStaticVoidMethod(env, clazz, mid);
+    }
+}