test/tck/LockSupportTest.java

/*
 * Written by Doug Lea and Martin Buchholz with assistance from
 * members of JCP JSR-166 Expert Group and released to the public
 * domain, as explained at
 * http://creativecommons.org/publicdomain/zero/1.0/
 * Other contributors include Andrew Wright, Jeffrey Hayes,
 * Pat Fisher, Mike Judd.
 */

import static java.util.concurrent.TimeUnit.MILLISECONDS;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.locks.LockSupport;

import junit.framework.Test;
import junit.framework.TestSuite;

public class LockSupportTest extends JSR166TestCase {
    public static void main(String[] args) {
        main(suite(), args);
    }

    public static Test suite() {
        return new TestSuite(LockSupportTest.class);
    }

    static {
        // Reduce the risk of rare disastrous classloading in first call to
        // LockSupport.park: https://bugs.openjdk.java.net/browse/JDK-8074773
        Class<?> ensureLoaded = LockSupport.class;
    }

    /**
     * Returns the blocker object used by tests in this file.
     * Any old object will do; we'll return a convenient one.
     */
    static Object theBlocker() {
        return LockSupportTest.class;
    }

    enum ParkMethod {
        park() {
            void park() {
                LockSupport.park();
            }
            void park(long millis) {
                throw new UnsupportedOperationException();
            }
        },
        parkUntil() {
            void park(long millis) {
                LockSupport.parkUntil(deadline(millis));
            }
        },
        parkNanos() {
            void park(long millis) {
                LockSupport.parkNanos(MILLISECONDS.toNanos(millis));
            }
        },
        parkBlocker() {
            void park() {
                LockSupport.park(theBlocker());
            }
            void park(long millis) {
                throw new UnsupportedOperationException();
            }
        },
        parkUntilBlocker() {
            void park(long millis) {
                LockSupport.parkUntil(theBlocker(), deadline(millis));
            }
        },
        parkNanosBlocker() {
            void park(long millis) {
                LockSupport.parkNanos(theBlocker(),
                                      MILLISECONDS.toNanos(millis));
            }
        };

        void park() { park(2 * LONG_DELAY_MS); }
        abstract void park(long millis);

        /** Returns a deadline to use with parkUntil. */
        long deadline(long millis) {
            // beware of rounding
            return System.currentTimeMillis() + millis + 1;
        }
    }

    /**
     * park is released by subsequent unpark
     */
    public void testParkBeforeUnpark_park() {
        testParkBeforeUnpark(ParkMethod.park);
    }
    public void testParkBeforeUnpark_parkNanos() {
        testParkBeforeUnpark(ParkMethod.parkNanos);
    }
    public void testParkBeforeUnpark_parkUntil() {
        testParkBeforeUnpark(ParkMethod.parkUntil);
    }
    public void testParkBeforeUnpark_parkBlocker() {
        testParkBeforeUnpark(ParkMethod.parkBlocker);
    }
    public void testParkBeforeUnpark_parkNanosBlocker() {
        testParkBeforeUnpark(ParkMethod.parkNanosBlocker);
    }
    public void testParkBeforeUnpark_parkUntilBlocker() {
        testParkBeforeUnpark(ParkMethod.parkUntilBlocker);
    }
    public void testParkBeforeUnpark(final ParkMethod parkMethod) {
        final CountDownLatch pleaseUnpark = new CountDownLatch(1);
        Thread t = newStartedThread(new CheckedRunnable() {
            public void realRun() {
                pleaseUnpark.countDown();
                parkMethod.park();
            }});

        await(pleaseUnpark);
        LockSupport.unpark(t);
        awaitTermination(t);
    }

    /**
     * park is released by preceding unpark
     */
    public void testParkAfterUnpark_park() {
        testParkAfterUnpark(ParkMethod.park);
    }
    public void testParkAfterUnpark_parkNanos() {
        testParkAfterUnpark(ParkMethod.parkNanos);
    }
    public void testParkAfterUnpark_parkUntil() {
        testParkAfterUnpark(ParkMethod.parkUntil);
    }
    public void testParkAfterUnpark_parkBlocker() {
        testParkAfterUnpark(ParkMethod.parkBlocker);
    }
    public void testParkAfterUnpark_parkNanosBlocker() {
        testParkAfterUnpark(ParkMethod.parkNanosBlocker);
    }
    public void testParkAfterUnpark_parkUntilBlocker() {
        testParkAfterUnpark(ParkMethod.parkUntilBlocker);
    }
    public void testParkAfterUnpark(final ParkMethod parkMethod) {
        final CountDownLatch pleaseUnpark = new CountDownLatch(1);
        final AtomicBoolean pleasePark = new AtomicBoolean(false);
        Thread t = newStartedThread(new CheckedRunnable() {
            public void realRun() {
                pleaseUnpark.countDown();
                while (!pleasePark.get())
                    Thread.yield();
                parkMethod.park();
            }});

        await(pleaseUnpark);
        LockSupport.unpark(t);
        pleasePark.set(true);
        awaitTermination(t);
    }

    /**
     * park is released by subsequent interrupt
     */
    public void testParkBeforeInterrupt_park() {
        testParkBeforeInterrupt(ParkMethod.park);
    }
    public void testParkBeforeInterrupt_parkNanos() {
        testParkBeforeInterrupt(ParkMethod.parkNanos);
    }
    public void testParkBeforeInterrupt_parkUntil() {
        testParkBeforeInterrupt(ParkMethod.parkUntil);
    }
    public void testParkBeforeInterrupt_parkBlocker() {
        testParkBeforeInterrupt(ParkMethod.parkBlocker);
    }
    public void testParkBeforeInterrupt_parkNanosBlocker() {
        testParkBeforeInterrupt(ParkMethod.parkNanosBlocker);
    }
    public void testParkBeforeInterrupt_parkUntilBlocker() {
        testParkBeforeInterrupt(ParkMethod.parkUntilBlocker);
    }
    public void testParkBeforeInterrupt(final ParkMethod parkMethod) {
        final CountDownLatch pleaseInterrupt = new CountDownLatch(1);
        Thread t = newStartedThread(new CheckedRunnable() {
            public void realRun() {
                pleaseInterrupt.countDown();
                do {
                    parkMethod.park();
                    // park may return spuriously
                } while (! Thread.currentThread().isInterrupted());
            }});

        await(pleaseInterrupt);
        assertThreadStaysAlive(t);
        t.interrupt();
        awaitTermination(t);
    }

    /**
     * park is released by preceding interrupt
     */
    public void testParkAfterInterrupt_park() {
        testParkAfterInterrupt(ParkMethod.park);
    }
    public void testParkAfterInterrupt_parkNanos() {
        testParkAfterInterrupt(ParkMethod.parkNanos);
    }
    public void testParkAfterInterrupt_parkUntil() {
        testParkAfterInterrupt(ParkMethod.parkUntil);
    }
    public void testParkAfterInterrupt_parkBlocker() {
        testParkAfterInterrupt(ParkMethod.parkBlocker);
    }
    public void testParkAfterInterrupt_parkNanosBlocker() {
        testParkAfterInterrupt(ParkMethod.parkNanosBlocker);
    }
    public void testParkAfterInterrupt_parkUntilBlocker() {
        testParkAfterInterrupt(ParkMethod.parkUntilBlocker);
    }
    public void testParkAfterInterrupt(final ParkMethod parkMethod) {
        final CountDownLatch pleaseInterrupt = new CountDownLatch(1);
        final AtomicBoolean pleasePark = new AtomicBoolean(false);
        Thread t = newStartedThread(new CheckedRunnable() {
            public void realRun() throws Exception {
                pleaseInterrupt.countDown();
                while (!pleasePark.get())
                    Thread.yield();
                assertTrue(Thread.currentThread().isInterrupted());
                parkMethod.park();
                assertTrue(Thread.currentThread().isInterrupted());
            }});

        await(pleaseInterrupt);
        t.interrupt();
        pleasePark.set(true);
        awaitTermination(t);
    }

    /**
     * timed park times out if not unparked
     */
    public void testParkTimesOut_parkNanos() {
        testParkTimesOut(ParkMethod.parkNanos);
    }
    public void testParkTimesOut_parkUntil() {
        testParkTimesOut(ParkMethod.parkUntil);
    }
    public void testParkTimesOut_parkNanosBlocker() {
        testParkTimesOut(ParkMethod.parkNanosBlocker);
    }
    public void testParkTimesOut_parkUntilBlocker() {
        testParkTimesOut(ParkMethod.parkUntilBlocker);
    }
    public void testParkTimesOut(final ParkMethod parkMethod) {
        Thread t = newStartedThread(new CheckedRunnable() {
            public void realRun() {
                for (int tries = MAX_SPURIOUS_WAKEUPS; tries-->0; ) {
                    long startTime = System.nanoTime();
                    parkMethod.park(timeoutMillis());
                    // park may return spuriously
                    if (millisElapsedSince(startTime) >= timeoutMillis())
                        return;
                }
                fail("too many consecutive spurious wakeups?");
            }});

        awaitTermination(t);
    }

    /**
     * getBlocker(null) throws NullPointerException
     */
    public void testGetBlockerNull() {
        try {
            LockSupport.getBlocker(null);
            shouldThrow();
        } catch (NullPointerException success) {}
    }

    /**
     * getBlocker returns the blocker object passed to park
     */
    public void testGetBlocker_parkBlocker() {
        testGetBlocker(ParkMethod.parkBlocker);
    }
    public void testGetBlocker_parkNanosBlocker() {
        testGetBlocker(ParkMethod.parkNanosBlocker);
    }
    public void testGetBlocker_parkUntilBlocker() {
        testGetBlocker(ParkMethod.parkUntilBlocker);
    }
    public void testGetBlocker(final ParkMethod parkMethod) {
        final CountDownLatch started = new CountDownLatch(1);
        Thread t = newStartedThread(new CheckedRunnable() {
            public void realRun() {
                Thread t = Thread.currentThread();
                started.countDown();
                do {
                    assertNull(LockSupport.getBlocker(t));
                    parkMethod.park();
                    assertNull(LockSupport.getBlocker(t));
                    // park may return spuriously
                } while (! Thread.currentThread().isInterrupted());
            }});

        long startTime = System.nanoTime();
        await(started);
        for (;;) {
            Object x = LockSupport.getBlocker(t);
            if (x == theBlocker()) { // success
                t.interrupt();
                awaitTermination(t);
                assertNull(LockSupport.getBlocker(t));
                return;
            } else {
                assertNull(x);  // ok
                if (millisElapsedSince(startTime) > LONG_DELAY_MS)
                    fail("timed out");
                Thread.yield();
            }
        }
    }

    /**
     * timed park(0) returns immediately.
     *
     * Requires hotspot fix for:
     * 6763959 java.util.concurrent.locks.LockSupport.parkUntil(0) blocks forever
     * which is in jdk7-b118 and 6u25.
     */
    public void testPark0_parkNanos() {
        testPark0(ParkMethod.parkNanos);
    }
    public void testPark0_parkUntil() {
        testPark0(ParkMethod.parkUntil);
    }
    public void testPark0_parkNanosBlocker() {
        testPark0(ParkMethod.parkNanosBlocker);
    }
    public void testPark0_parkUntilBlocker() {
        testPark0(ParkMethod.parkUntilBlocker);
    }
    public void testPark0(final ParkMethod parkMethod) {
        Thread t = newStartedThread(new CheckedRunnable() {
            public void realRun() {
                parkMethod.park(0L);
            }});

        awaitTermination(t);
    }

    /**
     * timed park(Long.MIN_VALUE) returns immediately.
     */
    public void testParkNeg_parkNanos() {
        testParkNeg(ParkMethod.parkNanos);
    }
    public void testParkNeg_parkUntil() {
        testParkNeg(ParkMethod.parkUntil);
    }
    public void testParkNeg_parkNanosBlocker() {
        testParkNeg(ParkMethod.parkNanosBlocker);
    }
    public void testParkNeg_parkUntilBlocker() {
        testParkNeg(ParkMethod.parkUntilBlocker);
    }
    public void testParkNeg(final ParkMethod parkMethod) {
        Thread t = newStartedThread(new CheckedRunnable() {
            public void realRun() {
                parkMethod.park(Long.MIN_VALUE);
            }});

        awaitTermination(t);
    }
}
Revision:	1.27
Committed:	Fri May 12 18:12:52 2017 UTC (7 years ago) by jsr166
Branch:	MAIN
Changes since 1.26:	+2 -1 lines
Log Message:	introduce MAX_SPURIOUS_WAKEUPS
#	Content
1	/*
2	* Written by Doug Lea and Martin Buchholz with assistance from
3	* members of JCP JSR-166 Expert Group and released to the public
4	* domain, as explained at
5	* http://creativecommons.org/publicdomain/zero/1.0/
6	* Other contributors include Andrew Wright, Jeffrey Hayes,
7	* Pat Fisher, Mike Judd.
8	*/
9
10	import static java.util.concurrent.TimeUnit.MILLISECONDS;
11
12	import java.util.concurrent.CountDownLatch;
13	import java.util.concurrent.atomic.AtomicBoolean;
14	import java.util.concurrent.locks.LockSupport;
15
16	import junit.framework.Test;
17	import junit.framework.TestSuite;
18
19	public class LockSupportTest extends JSR166TestCase {
20	public static void main(String[] args) {
21	main(suite(), args);
22	}
23
24	public static Test suite() {
25	return new TestSuite(LockSupportTest.class);
26	}
27
28	static {
29	// Reduce the risk of rare disastrous classloading in first call to
30	// LockSupport.park: https://bugs.openjdk.java.net/browse/JDK-8074773
31	Class<?> ensureLoaded = LockSupport.class;
32	}
33
34	/**
35	* Returns the blocker object used by tests in this file.
36	* Any old object will do; we'll return a convenient one.
37	*/
38	static Object theBlocker() {
39	return LockSupportTest.class;
40	}
41
42	enum ParkMethod {
43	park() {
44	void park() {
45	LockSupport.park();
46	}
47	void park(long millis) {
48	throw new UnsupportedOperationException();
49	}
50	},
51	parkUntil() {
52	void park(long millis) {
53	LockSupport.parkUntil(deadline(millis));
54	}
55	},
56	parkNanos() {
57	void park(long millis) {
58	LockSupport.parkNanos(MILLISECONDS.toNanos(millis));
59	}
60	},
61	parkBlocker() {
62	void park() {
63	LockSupport.park(theBlocker());
64	}
65	void park(long millis) {
66	throw new UnsupportedOperationException();
67	}
68	},
69	parkUntilBlocker() {
70	void park(long millis) {
71	LockSupport.parkUntil(theBlocker(), deadline(millis));
72	}
73	},
74	parkNanosBlocker() {
75	void park(long millis) {
76	LockSupport.parkNanos(theBlocker(),
77	MILLISECONDS.toNanos(millis));
78	}
79	};
80
81	void park() { park(2 * LONG_DELAY_MS); }
82	abstract void park(long millis);
83
84	/** Returns a deadline to use with parkUntil. */
85	long deadline(long millis) {
86	// beware of rounding
87	return System.currentTimeMillis() + millis + 1;
88	}
89	}
90
91	/**
92	* park is released by subsequent unpark
93	*/
94	public void testParkBeforeUnpark_park() {
95	testParkBeforeUnpark(ParkMethod.park);
96	}
97	public void testParkBeforeUnpark_parkNanos() {
98	testParkBeforeUnpark(ParkMethod.parkNanos);
99	}
100	public void testParkBeforeUnpark_parkUntil() {
101	testParkBeforeUnpark(ParkMethod.parkUntil);
102	}
103	public void testParkBeforeUnpark_parkBlocker() {
104	testParkBeforeUnpark(ParkMethod.parkBlocker);
105	}
106	public void testParkBeforeUnpark_parkNanosBlocker() {
107	testParkBeforeUnpark(ParkMethod.parkNanosBlocker);
108	}
109	public void testParkBeforeUnpark_parkUntilBlocker() {
110	testParkBeforeUnpark(ParkMethod.parkUntilBlocker);
111	}
112	public void testParkBeforeUnpark(final ParkMethod parkMethod) {
113	final CountDownLatch pleaseUnpark = new CountDownLatch(1);
114	Thread t = newStartedThread(new CheckedRunnable() {
115	public void realRun() {
116	pleaseUnpark.countDown();
117	parkMethod.park();
118	}});
119
120	await(pleaseUnpark);
121	LockSupport.unpark(t);
122	awaitTermination(t);
123	}
124
125	/**
126	* park is released by preceding unpark
127	*/
128	public void testParkAfterUnpark_park() {
129	testParkAfterUnpark(ParkMethod.park);
130	}
131	public void testParkAfterUnpark_parkNanos() {
132	testParkAfterUnpark(ParkMethod.parkNanos);
133	}
134	public void testParkAfterUnpark_parkUntil() {
135	testParkAfterUnpark(ParkMethod.parkUntil);
136	}
137	public void testParkAfterUnpark_parkBlocker() {
138	testParkAfterUnpark(ParkMethod.parkBlocker);
139	}
140	public void testParkAfterUnpark_parkNanosBlocker() {
141	testParkAfterUnpark(ParkMethod.parkNanosBlocker);
142	}
143	public void testParkAfterUnpark_parkUntilBlocker() {
144	testParkAfterUnpark(ParkMethod.parkUntilBlocker);
145	}
146	public void testParkAfterUnpark(final ParkMethod parkMethod) {
147	final CountDownLatch pleaseUnpark = new CountDownLatch(1);
148	final AtomicBoolean pleasePark = new AtomicBoolean(false);
149	Thread t = newStartedThread(new CheckedRunnable() {
150	public void realRun() {
151	pleaseUnpark.countDown();
152	while (!pleasePark.get())
153	Thread.yield();
154	parkMethod.park();
155	}});
156
157	await(pleaseUnpark);
158	LockSupport.unpark(t);
159	pleasePark.set(true);
160	awaitTermination(t);
161	}
162
163	/**
164	* park is released by subsequent interrupt
165	*/
166	public void testParkBeforeInterrupt_park() {
167	testParkBeforeInterrupt(ParkMethod.park);
168	}
169	public void testParkBeforeInterrupt_parkNanos() {
170	testParkBeforeInterrupt(ParkMethod.parkNanos);
171	}
172	public void testParkBeforeInterrupt_parkUntil() {
173	testParkBeforeInterrupt(ParkMethod.parkUntil);
174	}
175	public void testParkBeforeInterrupt_parkBlocker() {
176	testParkBeforeInterrupt(ParkMethod.parkBlocker);
177	}
178	public void testParkBeforeInterrupt_parkNanosBlocker() {
179	testParkBeforeInterrupt(ParkMethod.parkNanosBlocker);
180	}
181	public void testParkBeforeInterrupt_parkUntilBlocker() {
182	testParkBeforeInterrupt(ParkMethod.parkUntilBlocker);
183	}
184	public void testParkBeforeInterrupt(final ParkMethod parkMethod) {
185	final CountDownLatch pleaseInterrupt = new CountDownLatch(1);
186	Thread t = newStartedThread(new CheckedRunnable() {
187	public void realRun() {
188	pleaseInterrupt.countDown();
189	do {
190	parkMethod.park();
191	// park may return spuriously
192	} while (! Thread.currentThread().isInterrupted());
193	}});
194
195	await(pleaseInterrupt);
196	assertThreadStaysAlive(t);
197	t.interrupt();
198	awaitTermination(t);
199	}
200
201	/**
202	* park is released by preceding interrupt
203	*/
204	public void testParkAfterInterrupt_park() {
205	testParkAfterInterrupt(ParkMethod.park);
206	}
207	public void testParkAfterInterrupt_parkNanos() {
208	testParkAfterInterrupt(ParkMethod.parkNanos);
209	}
210	public void testParkAfterInterrupt_parkUntil() {
211	testParkAfterInterrupt(ParkMethod.parkUntil);
212	}
213	public void testParkAfterInterrupt_parkBlocker() {
214	testParkAfterInterrupt(ParkMethod.parkBlocker);
215	}
216	public void testParkAfterInterrupt_parkNanosBlocker() {
217	testParkAfterInterrupt(ParkMethod.parkNanosBlocker);
218	}
219	public void testParkAfterInterrupt_parkUntilBlocker() {
220	testParkAfterInterrupt(ParkMethod.parkUntilBlocker);
221	}
222	public void testParkAfterInterrupt(final ParkMethod parkMethod) {
223	final CountDownLatch pleaseInterrupt = new CountDownLatch(1);
224	final AtomicBoolean pleasePark = new AtomicBoolean(false);
225	Thread t = newStartedThread(new CheckedRunnable() {
226	public void realRun() throws Exception {
227	pleaseInterrupt.countDown();
228	while (!pleasePark.get())
229	Thread.yield();
230	assertTrue(Thread.currentThread().isInterrupted());
231	parkMethod.park();
232	assertTrue(Thread.currentThread().isInterrupted());
233	}});
234
235	await(pleaseInterrupt);
236	t.interrupt();
237	pleasePark.set(true);
238	awaitTermination(t);
239	}
240
241	/**
242	* timed park times out if not unparked
243	*/
244	public void testParkTimesOut_parkNanos() {
245	testParkTimesOut(ParkMethod.parkNanos);
246	}
247	public void testParkTimesOut_parkUntil() {
248	testParkTimesOut(ParkMethod.parkUntil);
249	}
250	public void testParkTimesOut_parkNanosBlocker() {
251	testParkTimesOut(ParkMethod.parkNanosBlocker);
252	}
253	public void testParkTimesOut_parkUntilBlocker() {
254	testParkTimesOut(ParkMethod.parkUntilBlocker);
255	}
256	public void testParkTimesOut(final ParkMethod parkMethod) {
257	Thread t = newStartedThread(new CheckedRunnable() {
258	public void realRun() {
259	for (int tries = MAX_SPURIOUS_WAKEUPS; tries-->0; ) {
260	long startTime = System.nanoTime();
261	parkMethod.park(timeoutMillis());
262	// park may return spuriously
263	if (millisElapsedSince(startTime) >= timeoutMillis())
264	return;
265	}
266	fail("too many consecutive spurious wakeups?");
267	}});
268
269	awaitTermination(t);
270	}
271
272	/**
273	* getBlocker(null) throws NullPointerException
274	*/
275	public void testGetBlockerNull() {
276	try {
277	LockSupport.getBlocker(null);
278	shouldThrow();
279	} catch (NullPointerException success) {}
280	}
281
282	/**
283	* getBlocker returns the blocker object passed to park
284	*/
285	public void testGetBlocker_parkBlocker() {
286	testGetBlocker(ParkMethod.parkBlocker);
287	}
288	public void testGetBlocker_parkNanosBlocker() {
289	testGetBlocker(ParkMethod.parkNanosBlocker);
290	}
291	public void testGetBlocker_parkUntilBlocker() {
292	testGetBlocker(ParkMethod.parkUntilBlocker);
293	}
294	public void testGetBlocker(final ParkMethod parkMethod) {
295	final CountDownLatch started = new CountDownLatch(1);
296	Thread t = newStartedThread(new CheckedRunnable() {
297	public void realRun() {
298	Thread t = Thread.currentThread();
299	started.countDown();
300	do {
301	assertNull(LockSupport.getBlocker(t));
302	parkMethod.park();
303	assertNull(LockSupport.getBlocker(t));
304	// park may return spuriously
305	} while (! Thread.currentThread().isInterrupted());
306	}});
307
308	long startTime = System.nanoTime();
309	await(started);
310	for (;;) {
311	Object x = LockSupport.getBlocker(t);
312	if (x == theBlocker()) { // success
313	t.interrupt();
314	awaitTermination(t);
315	assertNull(LockSupport.getBlocker(t));
316	return;
317	} else {
318	assertNull(x); // ok
319	if (millisElapsedSince(startTime) > LONG_DELAY_MS)
320	fail("timed out");
321	Thread.yield();
322	}
323	}
324	}
325
326	/**
327	* timed park(0) returns immediately.
328	*
329	* Requires hotspot fix for:
330	* 6763959 java.util.concurrent.locks.LockSupport.parkUntil(0) blocks forever
331	* which is in jdk7-b118 and 6u25.
332	*/
333	public void testPark0_parkNanos() {
334	testPark0(ParkMethod.parkNanos);
335	}
336	public void testPark0_parkUntil() {
337	testPark0(ParkMethod.parkUntil);
338	}
339	public void testPark0_parkNanosBlocker() {
340	testPark0(ParkMethod.parkNanosBlocker);
341	}
342	public void testPark0_parkUntilBlocker() {
343	testPark0(ParkMethod.parkUntilBlocker);
344	}
345	public void testPark0(final ParkMethod parkMethod) {
346	Thread t = newStartedThread(new CheckedRunnable() {
347	public void realRun() {
348	parkMethod.park(0L);
349	}});
350
351	awaitTermination(t);
352	}
353
354	/**
355	* timed park(Long.MIN_VALUE) returns immediately.
356	*/
357	public void testParkNeg_parkNanos() {
358	testParkNeg(ParkMethod.parkNanos);
359	}
360	public void testParkNeg_parkUntil() {
361	testParkNeg(ParkMethod.parkUntil);
362	}
363	public void testParkNeg_parkNanosBlocker() {
364	testParkNeg(ParkMethod.parkNanosBlocker);
365	}
366	public void testParkNeg_parkUntilBlocker() {
367	testParkNeg(ParkMethod.parkUntilBlocker);
368	}
369	public void testParkNeg(final ParkMethod parkMethod) {
370	Thread t = newStartedThread(new CheckedRunnable() {
371	public void realRun() {
372	parkMethod.park(Long.MIN_VALUE);
373	}});
374
375	awaitTermination(t);
376	}
377	}