--- jsr166/src/test/tck/JSR166TestCase.java	2019/09/07 17:40:05	1.266
+++ jsr166/src/test/tck/JSR166TestCase.java	2019/09/26 20:48:52	1.269
@@ -49,6 +49,7 @@ import java.io.ByteArrayOutputStream;
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 import java.lang.management.ManagementFactory;
+import java.lang.management.LockInfo;
 import java.lang.management.ThreadInfo;
 import java.lang.management.ThreadMXBean;
 import java.lang.reflect.Constructor;
@@ -243,6 +244,9 @@ public class JSR166TestCase extends Test
         }
     }
 
+    private static final ThreadMXBean THREAD_MXBEAN
+        = ManagementFactory.getThreadMXBean();
+
     /**
      * The scaling factor to apply to standard delays used in tests.
      * May be initialized from any of:
@@ -354,7 +358,7 @@ public class JSR166TestCase extends Test
             // Never report first run of any test; treat it as a
             // warmup run, notably to trigger all needed classloading,
             if (i > 0)
-                System.out.printf("%n%s: %d%n", toString(), elapsedMillis);
+                System.out.printf("%s: %d%n", toString(), elapsedMillis);
         }
     }
 
@@ -1130,9 +1134,8 @@ public class JSR166TestCase extends Test
             }
         }
 
-        ThreadMXBean threadMXBean = ManagementFactory.getThreadMXBean();
         System.err.println("------ stacktrace dump start ------");
-        for (ThreadInfo info : threadMXBean.dumpAllThreads(true, true))
+        for (ThreadInfo info : THREAD_MXBEAN.dumpAllThreads(true, true))
             if (threadOfInterest(info))
                 System.err.print(info);
         System.err.println("------ stacktrace dump end ------");
@@ -1161,6 +1164,17 @@ public class JSR166TestCase extends Test
     }
 
     /**
+     * Returns the thread's blocker's class name, if any, else null.
+     */
+    String blockerClassName(Thread thread) {
+        ThreadInfo threadInfo; LockInfo lockInfo;
+        if ((threadInfo = THREAD_MXBEAN.getThreadInfo(thread.getId(), 0)) != null
+            && (lockInfo = threadInfo.getLockInfo()) != null)
+            return lockInfo.getClassName();
+        return null;
+    }
+
+    /**
      * Checks that future.get times out, with the default timeout of
      * {@code timeoutMillis()}.
      */
@@ -1459,6 +1473,14 @@ public class JSR166TestCase extends Test
     }
 
     /**
+     * Returns a new started daemon Thread running the given action,
+     * wrapped in a CheckedRunnable.
+     */
+    Thread newStartedThread(Action action) {
+        return newStartedThread(checkedRunnable(action));
+    }
+
+    /**
      * Waits for the specified time (in milliseconds) for the thread
      * to terminate (using {@link Thread#join(long)}), else interrupts
      * the thread (in the hope that it may terminate later) and fails.
@@ -1505,6 +1527,13 @@ public class JSR166TestCase extends Test
         }
     }
 
+    Runnable checkedRunnable(Action action) {
+        return new CheckedRunnable() {
+            public void realRun() throws Throwable {
+                action.run();
+            }};
+    }
+
     public abstract class ThreadShouldThrow extends Thread {
         protected abstract void realRun() throws Throwable;