ART: Rewrite ParallelGC run-test

To better test what ParallelGC is intended to do, write a version
that will more fairly allocate objects between the threads, and
will let each thread OOM only once. Use a barrier to wait for
completion of all threads, and force a final GC by allocating some
more objects.

Bug: 16406852
Change-Id: I019ddc08515b9610c18d55280cd46cbe3ae3e5ac

1 files changed, 111 insertions, 11 deletions

diff --git a/test/114-ParallelGC/src/Main.java b/test/114-ParallelGC/src/Main.java
index 15d5e50796..8e2519dd0a 100644
--- a/test/114-ParallelGC/src/Main.java
+++ b/test/114-ParallelGC/src/Main.java
@@ -16,38 +16,138 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.BrokenBarrierException;
+import java.util.concurrent.CyclicBarrier;
+import java.util.concurrent.SynchronousQueue;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
 
 public class Main implements Runnable {
+
+    public final static long TIMEOUT_VALUE = 5;  // Timeout in minutes.
+    public final static long MAX_SIZE = 1000;  // Maximum size of array-list to allocate.
+
     public static void main(String[] args) throws Exception {
         Thread[] threads = new Thread[16];
+
+        // Use a cyclic system of synchronous queues to pass a boolean token around.
+        //
+        // The combinations are:
+        //
+        // Worker receives:    true     false    false    true
+        // Worker has OOM:     false    false    true     true
+        //    |
+        //    v
+        // Value to pass:      true     false    false    false
+        // Exit out of loop:   false    true     true     true
+        // Wait on in queue:   true     false    false    true
+        //
+        // Finally, the workers are supposed to wait on the barrier to synchronize the GC run.
+
+        CyclicBarrier barrier = new CyclicBarrier(threads.length);
+        List<SynchronousQueue<Boolean>> queues = new ArrayList<SynchronousQueue<Boolean>>(
+            threads.length);
+        for (int i = 0; i < threads.length; i++) {
+            queues.add(new SynchronousQueue<Boolean>());
+        }
+
         for (int i = 0; i < threads.length; i++) {
-            threads[i] = new Thread(new Main(i));
+            threads[i] = new Thread(new Main(i, queues.get(i), queues.get((i + 1) % threads.length),
+                                             barrier));
         }
         for (Thread thread : threads) {
             thread.start();
         }
+
+        // Push off the cycle.
+        checkTimeout(queues.get(0).offer(Boolean.TRUE, TIMEOUT_VALUE, TimeUnit.MINUTES));
+
+        // Wait for the threads to finish.
         for (Thread thread : threads) {
             thread.join();
         }
+
+        // Allocate objects to definitely run GC before quitting.
+        try {
+            for (int i = 0; i < 1000; i++) {
+                new ArrayList<Object>(i);
+            }
+        } catch (OutOfMemoryError oom) {
+        }
+    }
+
+    private static void checkTimeout(Object o) {
+        checkTimeout(o != null);
+    }
+
+    private static void checkTimeout(boolean b) {
+        if (!b) {
+            // Something went wrong.
+            System.out.println("Bad things happened, timeout.");
+            System.exit(1);
+        }
     }
 
     private final int id;
+    private final SynchronousQueue<Boolean> waitOn;
+    private final SynchronousQueue<Boolean> pushTo;
+    private final CyclicBarrier finalBarrier;
 
-    private Main(int id) {
+    private Main(int id, SynchronousQueue<Boolean> waitOn, SynchronousQueue<Boolean> pushTo,
+        CyclicBarrier finalBarrier) {
         this.id = id;
-        // Allocate this early so it's independent of how the threads are scheduled on startup.
-        this.l = new ArrayList<Object>();
+        this.waitOn = waitOn;
+        this.pushTo = pushTo;
+        this.finalBarrier = finalBarrier;
     }
 
     public void run() {
-        for (int i = 0; i < 1000; i++) {
-            try {
-                l.add(new ArrayList<Object>(i));
-            } catch (OutOfMemoryError oom) {
-                // Ignore.
-            }
+        try {
+            work();
+        } catch (Exception exc) {
+            // Any exception is bad.
+            exc.printStackTrace(System.err);
+            System.exit(1);
         }
     }
 
-    private List<Object> l;
+    public void work() throws BrokenBarrierException, InterruptedException, TimeoutException {
+        ArrayList<Object> l = new ArrayList<Object>();
+
+        // Main loop.
+        for (int i = 0; ; i++) {
+          Boolean receivedB = waitOn.poll(TIMEOUT_VALUE, TimeUnit.MINUTES);
+          checkTimeout(receivedB);
+          boolean received = receivedB;
+
+          // This is the first stage, try to allocate up till MAX_SIZE.
+          boolean oom = i >= MAX_SIZE;
+          try {
+            l.add(new ArrayList<Object>(i));
+          } catch (OutOfMemoryError oome) {
+            oom = true;
+          }
+
+          if (!received || oom) {
+            // First stage, always push false.
+            checkTimeout(pushTo.offer(Boolean.FALSE, TIMEOUT_VALUE, TimeUnit.MINUTES));
+
+            // If we received true, wait for the false to come around.
+            if (received) {
+              checkTimeout(waitOn.poll(TIMEOUT_VALUE, TimeUnit.MINUTES));
+            }
+
+            // Break out of the loop.
+            break;
+          } else {
+            // Pass on true.
+            checkTimeout(pushTo.offer(Boolean.TRUE, TIMEOUT_VALUE, TimeUnit.MINUTES));
+          }
+        }
+
+        // We have reached the final point. Wait on the barrier, but at most a minute.
+        finalBarrier.await(TIMEOUT_VALUE, TimeUnit.MINUTES);
+
+        // Done.
+    }
 }