Merge pull request #18365 from tajila/issue3

Add addition testing for ThreadMXBean thread alloc

test/functional/JLM_Tests/src/org/openj9/test/java/lang/management/TestThreadMXBean.java

@@ -36,6 +36,7 @@
 import java.util.Hashtable;
 import java.util.Iterator;
 import java.util.Map;
+import java.util.concurrent.atomic.AtomicInteger;
 
 import javax.management.Attribute;
 import javax.management.AttributeList;
@@ -1097,6 +1098,96 @@ public final void testThreadAllocationMetricsOnCurrentThread() {
 		AssertJUnit.assertTrue(bytes5 >= bytes4);
 	}
 
+	private final void allocateAndWait(int allocCount, Object sync, AtomicInteger count) {
+		try {
+			ArrayList list = new ArrayList<>();
+
+			for (int i = 0; i < allocCount; i++) {
+				list.add(new Object[100]);
+			}
+
+			count.getAndIncrement();
+
+			synchronized (sync) {
+				sync.wait();
+			}
+		} catch (InterruptedException e) {
+			e.printStackTrace();
+			AssertJUnit.fail(e.getMessage());
+		}
+	}
+
+	/**
+	 * Allocate differing amounts of objects on each thread and ensure that
+	 * threadMXbean getThreadAllocatedBytes correctly reports the relative
+	 * allocated amounts.
+	 *
+	 * @throws InterruptedException
+	 */
+	@Test
+	public final void testThreadAllocationMetrics() throws InterruptedException {
+		com.sun.management.ThreadMXBean sunTB = (com.sun.management.ThreadMXBean)tb;
+
+		final Object sync = new Object() {};
+		final AtomicInteger count = new AtomicInteger(0);
+
+		Thread t1 = new Thread(()->{
+			allocateAndWait(1000, sync, count);
+		});
+
+		Thread t2 = new Thread(()->{
+			allocateAndWait(2000, sync, count);
+		});
+
+		Thread t3 = new Thread(()->{
+			allocateAndWait(1, sync, count);
+		});
+
+		t1.start();
+		t2.start();
+		t3.start();
+
+		Thread.yield();
+		Thread.yield();
+		Thread.yield();
+
+		/* Wait for threads to complete allocations or 10 seconds */
+		for (int i = 0; (count.get() < 3) || (i < 100); i++) {
+			Thread.sleep(100);
+		}
+
+		if (count.get() != 3) {
+			AssertJUnit.fail("Threads did not complete allocations in allotted time.");
+		}
+
+		/* Allocation stats are updated after a GC. */
+		System.gc();
+
+		/* Check stats with `long getThreadAllocatedBytes(long tid)`. */
+		long t1Stats = sunTB.getThreadAllocatedBytes(t1.getId());
+		long t2Stats = sunTB.getThreadAllocatedBytes(t2.getId());
+		long t3Stats = sunTB.getThreadAllocatedBytes(t3.getId());
+
+		AssertJUnit.assertTrue(t2Stats > t1Stats);
+		AssertJUnit.assertTrue(t1Stats > t3Stats);
+
+		/* Check stats with `long[] getThreadAllocatedBytes(long[] tids)`. */
+		long[] threadIDs = new long[] {t1.getId(), t2.getId(), t3.getId()};
+		long[] threadStats = sunTB.getThreadAllocatedBytes(threadIDs);
+
+		AssertJUnit.assertTrue(threadStats[1] > threadStats[0]);
+		AssertJUnit.assertTrue(threadStats[0] > threadStats[2]);
+
+		/* Wake up threads and wait for them to terminate */
+		synchronized (sync) {
+			sync.notifyAll();
+		}
+
+		t1.join();
+		t2.join();
+		t3.join();
+	}
+
 	@Test
 	public final void testGetAttributes() {
 		AttributeList attributes = null;