[POOL-419] Add failing tests for POOL-419.

Author: Raju Kumar Gupta

src/test/java/org/apache/commons/pool3/TestPoolUtils.java

@@ -21,6 +21,7 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assertions.fail;
 
 import java.lang.reflect.InvocationHandler;
@@ -33,10 +34,16 @@
 import java.util.List;
 import java.util.Map;
 import java.util.TimerTask;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.FutureTask;
+import java.util.concurrent.TimeUnit;
 
 import org.apache.commons.pool3.impl.DefaultPooledObject;
 import org.apache.commons.pool3.impl.GenericKeyedObjectPool;
 import org.apache.commons.pool3.impl.GenericObjectPool;
+import org.apache.commons.pool3.impl.GenericObjectPoolConfig;
 import org.junit.jupiter.api.Test;
 import org.opentest4j.AssertionFailedError;
 
@@ -684,4 +691,60 @@ public void testTimerHolder() {
         assertNotNull(h);
         assertNotNull(PoolUtils.TimerHolder.MIN_IDLE_TIMER);
     }
+
+    /*
+    * Test for POOL-419.
+    * https://issues.apache.org/jira/browse/POOL-419
+    */
+    @Test
+    void testPool419() throws Exception{
+
+        ExecutorService executor = Executors.newFixedThreadPool(100);
+
+        final List<String> calledMethods = new ArrayList<>();
+
+        final GenericObjectPoolConfig<Object> config = new GenericObjectPoolConfig<>();
+
+        config.setMaxTotal(10000);
+        config.setMaxIdle(10000);
+        config.setMinIdle(10000);
+
+        @SuppressWarnings("unchecked")
+        final PooledObjectFactory<Object, RuntimeException> pof = createProxy(PooledObjectFactory.class, calledMethods);
+        try (final ObjectPool<Object, RuntimeException> connectionPool = new GenericObjectPool<>(pof, config)) {
+            assertNotNull(connectionPool);
+
+            CountDownLatch startLatch = new CountDownLatch(1);
+
+            for (int i = 0; i < 10000; i++) {
+                Object poolObject = connectionPool.borrowObject();
+
+                FutureTask<Boolean> invalidateObject = new FutureTask<>(() -> {
+                    startLatch.await();
+                    connectionPool.invalidateObject(poolObject);
+                    return true;
+                });
+
+                FutureTask<Boolean> returnObject = new FutureTask<>(() -> {
+                    startLatch.await();
+                    connectionPool.returnObject(poolObject);
+                    return true;
+                });
+
+                executor.submit(returnObject);
+                executor.submit(invalidateObject);
+
+            }
+
+            startLatch.countDown(); // Start all tasks simultaneously
+
+            executor.shutdown();
+            assertTrue(executor.awaitTermination(Long.MAX_VALUE, TimeUnit.NANOSECONDS));
+
+            assertEquals(0, connectionPool.getNumActive(), "getNumActive() must not return a negative value");
+
+        }
+    }
+
 }
+