@Test
public void testSafetyNetClose() throws Exception {

	setup(20);
	startThreads();
	joinThreads();
	for (int i = 0; i < 5 && unclosedCounter.get() > 0; ++i) {
		System.gc();
		Thread.sleep(50);
	}
	Assert.assertEquals(0, unclosedCounter.get());
	closeableRegistry.close();
}