test/tck/ThreadLocalRandomTest.java

/*
 * Written by Doug Lea 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/
 */

import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;

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

public class ThreadLocalRandomTest extends JSR166TestCase {

    public static void main(String[] args) {
        main(suite(), args);
    }
    public static Test suite() {
        return new TestSuite(ThreadLocalRandomTest.class);
    }

    /*
     * Testing coverage notes:
     *
     * We don't test randomness properties, but only that repeated
     * calls, up to NCALLS tries, produce at least one different
     * result.  For bounded versions, we sample various intervals
     * across multiples of primes.
     */

    // max numbers of calls to detect getting stuck on one value
    static final int NCALLS = 10000;

    // max sampled int bound
    static final int MAX_INT_BOUND = (1 << 28);

    // max sampled long bound
    static final long MAX_LONG_BOUND = (1L << 42);

    // Number of replications for other checks
    static final int REPS = 20;

    /**
     * setSeed throws UnsupportedOperationException
     */
    public void testSetSeed() {
        try {
            ThreadLocalRandom.current().setSeed(17);
            shouldThrow();
        } catch (UnsupportedOperationException success) {}
    }

    /**
     * Repeated calls to next (only accessible via reflection) produce
     * at least two distinct results, and repeated calls produce all
     * possible values.
     */
    public void testNext() throws ReflectiveOperationException {
        ThreadLocalRandom rnd = ThreadLocalRandom.current();
        final java.lang.reflect.Method m;
        try {
            m = ThreadLocalRandom.class.getDeclaredMethod(
                    "next", new Class[] { int.class });
            m.setAccessible(true);
        } catch (SecurityException acceptable) {
            // Security manager may deny access
            return;
        } catch (Exception ex) {
            // jdk9 module system may deny access
            if (ex.getClass().getSimpleName()
                .equals("InaccessibleObjectException"))
                return;
            throw ex;
        }

        int i;
        {
            int val = new java.util.Random().nextInt(4);
            for (i = 0; i < NCALLS; i++) {
                int q = (int) m.invoke(rnd, new Object[] { 2 });
                if (val == q) break;
            }
            assertTrue(i < NCALLS);
        }

        {
            int r = (int) m.invoke(rnd, new Object[] { 3 });
            for (i = 0; i < NCALLS; i++) {
                int q = (int) m.invoke(rnd, new Object[] { 3 });
                assertTrue(q < (1<<3));
                if (r != q) break;
            }
            assertTrue(i < NCALLS);
        }
    }

    /**
     * Repeated calls to nextInt produce at least two distinct results
     */
    public void testNextInt() {
        int f = ThreadLocalRandom.current().nextInt();
        int i = 0;
        while (i < NCALLS && ThreadLocalRandom.current().nextInt() == f)
            ++i;
        assertTrue(i < NCALLS);
    }

    /**
     * Repeated calls to nextLong produce at least two distinct results
     */
    public void testNextLong() {
        long f = ThreadLocalRandom.current().nextLong();
        int i = 0;
        while (i < NCALLS && ThreadLocalRandom.current().nextLong() == f)
            ++i;
        assertTrue(i < NCALLS);
    }

    /**
     * Repeated calls to nextBoolean produce at least two distinct results
     */
    public void testNextBoolean() {
        boolean f = ThreadLocalRandom.current().nextBoolean();
        int i = 0;
        while (i < NCALLS && ThreadLocalRandom.current().nextBoolean() == f)
            ++i;
        assertTrue(i < NCALLS);
    }

    /**
     * Repeated calls to nextFloat produce at least two distinct results
     */
    public void testNextFloat() {
        float f = ThreadLocalRandom.current().nextFloat();
        int i = 0;
        while (i < NCALLS && ThreadLocalRandom.current().nextFloat() == f)
            ++i;
        assertTrue(i < NCALLS);
    }

    /**
     * Repeated calls to nextDouble produce at least two distinct results
     */
    public void testNextDouble() {
        double f = ThreadLocalRandom.current().nextDouble();
        int i = 0;
        while (i < NCALLS && ThreadLocalRandom.current().nextDouble() == f)
            ++i;
        assertTrue(i < NCALLS);
    }

    /**
     * Repeated calls to nextGaussian produce at least two distinct results
     */
    public void testNextGaussian() {
        double f = ThreadLocalRandom.current().nextGaussian();
        int i = 0;
        while (i < NCALLS && ThreadLocalRandom.current().nextGaussian() == f)
            ++i;
        assertTrue(i < NCALLS);
    }

    /**
     * nextInt(non-positive) throws IllegalArgumentException
     */
    public void testNextIntBoundNonPositive() {
        ThreadLocalRandom rnd = ThreadLocalRandom.current();
        for (int bound : new int[] { 0, -17, Integer.MIN_VALUE }) {
            try {
                rnd.nextInt(bound);
                shouldThrow();
            } catch (IllegalArgumentException success) {}
        }
    }

    /**
     * nextInt(least >= bound) throws IllegalArgumentException
     */
    public void testNextIntBadBounds() {
        int[][] badBoundss = {
            { 17, 2 },
            { -42, -42 },
            { Integer.MAX_VALUE, Integer.MIN_VALUE },
        };
        ThreadLocalRandom rnd = ThreadLocalRandom.current();
        for (int[] badBounds : badBoundss) {
            try {
                rnd.nextInt(badBounds[0], badBounds[1]);
                shouldThrow();
            } catch (IllegalArgumentException success) {}
        }
    }

    /**
     * nextInt(bound) returns 0 <= value < bound;
     * repeated calls produce at least two distinct results
     */
    public void testNextIntBounded() {
        // sample bound space across prime number increments
        for (int bound = 2; bound < MAX_INT_BOUND; bound += 524959) {
            int f = ThreadLocalRandom.current().nextInt(bound);
            assertTrue(0 <= f && f < bound);
            int i = 0;
            int j;
            while (i < NCALLS &&
                   (j = ThreadLocalRandom.current().nextInt(bound)) == f) {
                assertTrue(0 <= j && j < bound);
                ++i;
            }
            assertTrue(i < NCALLS);
        }
    }

    /**
     * nextInt(least, bound) returns least <= value < bound;
     * repeated calls produce at least two distinct results
     */
    public void testNextIntBounded2() {
        for (int least = -15485863; least < MAX_INT_BOUND; least += 524959) {
            for (int bound = least + 2; bound > least && bound < MAX_INT_BOUND; bound += 49979687) {
                int f = ThreadLocalRandom.current().nextInt(least, bound);
                assertTrue(least <= f && f < bound);
                int i = 0;
                int j;
                while (i < NCALLS &&
                       (j = ThreadLocalRandom.current().nextInt(least, bound)) == f) {
                    assertTrue(least <= j && j < bound);
                    ++i;
                }
                assertTrue(i < NCALLS);
            }
        }
    }

    /**
     * nextLong(non-positive) throws IllegalArgumentException
     */
    public void testNextLongBoundNonPositive() {
        ThreadLocalRandom rnd = ThreadLocalRandom.current();
        for (long bound : new long[] { 0L, -17L, Long.MIN_VALUE }) {
            try {
                rnd.nextLong(bound);
                shouldThrow();
            } catch (IllegalArgumentException success) {}
        }
    }

    /**
     * nextLong(least >= bound) throws IllegalArgumentException
     */
    public void testNextLongBadBounds() {
        long[][] badBoundss = {
            { 17L, 2L },
            { -42L, -42L },
            { Long.MAX_VALUE, Long.MIN_VALUE },
        };
        ThreadLocalRandom rnd = ThreadLocalRandom.current();
        for (long[] badBounds : badBoundss) {
            try {
                rnd.nextLong(badBounds[0], badBounds[1]);
                shouldThrow();
            } catch (IllegalArgumentException success) {}
        }
    }

    /**
     * nextLong(bound) returns 0 <= value < bound;
     * repeated calls produce at least two distinct results
     */
    public void testNextLongBounded() {
        for (long bound = 2; bound < MAX_LONG_BOUND; bound += 15485863) {
            long f = ThreadLocalRandom.current().nextLong(bound);
            assertTrue(0 <= f && f < bound);
            int i = 0;
            long j;
            while (i < NCALLS &&
                   (j = ThreadLocalRandom.current().nextLong(bound)) == f) {
                assertTrue(0 <= j && j < bound);
                ++i;
            }
            assertTrue(i < NCALLS);
        }
    }

    /**
     * nextLong(least, bound) returns least <= value < bound;
     * repeated calls produce at least two distinct results
     */
    public void testNextLongBounded2() {
        for (long least = -86028121; least < MAX_LONG_BOUND; least += 982451653L) {
            for (long bound = least + 2; bound > least && bound < MAX_LONG_BOUND; bound += Math.abs(bound * 7919)) {
                long f = ThreadLocalRandom.current().nextLong(least, bound);
                assertTrue(least <= f && f < bound);
                int i = 0;
                long j;
                while (i < NCALLS &&
                       (j = ThreadLocalRandom.current().nextLong(least, bound)) == f) {
                    assertTrue(least <= j && j < bound);
                    ++i;
                }
                assertTrue(i < NCALLS);
            }
        }
    }

    /**
     * nextDouble(non-positive) throws IllegalArgumentException
     */
    public void testNextDoubleBoundNonPositive() {
        ThreadLocalRandom rnd = ThreadLocalRandom.current();
        double[] badBounds = {
            0.0d,
            -17.0d,
            -Double.MIN_VALUE,
            Double.NEGATIVE_INFINITY,
            Double.NaN,
        };
        for (double bound : badBounds) {
            try {
                rnd.nextDouble(bound);
                shouldThrow();
            } catch (IllegalArgumentException success) {}
        }
    }

    /**
     * nextDouble(least, bound) returns least <= value < bound;
     * repeated calls produce at least two distinct results
     */
    public void testNextDoubleBounded2() {
        for (double least = 0.0001; least < 1.0e20; least *= 8) {
            for (double bound = least * 1.001; bound < 1.0e20; bound *= 16) {
                double f = ThreadLocalRandom.current().nextDouble(least, bound);
                assertTrue(least <= f && f < bound);
                int i = 0;
                double j;
                while (i < NCALLS &&
                       (j = ThreadLocalRandom.current().nextDouble(least, bound)) == f) {
                    assertTrue(least <= j && j < bound);
                    ++i;
                }
                assertTrue(i < NCALLS);
            }
        }
    }

    /**
     * Different threads produce different pseudo-random sequences
     */
    public void testDifferentSequences() {
        // Don't use main thread's ThreadLocalRandom - it is likely to
        // be polluted by previous tests.
        final AtomicReference<ThreadLocalRandom> threadLocalRandom =
            new AtomicReference<ThreadLocalRandom>();
        final AtomicLong rand = new AtomicLong();

        long firstRand = 0;
        ThreadLocalRandom firstThreadLocalRandom = null;

        Runnable getRandomState = new CheckedRunnable() {
            public void realRun() {
                ThreadLocalRandom current = ThreadLocalRandom.current();
                assertSame(current, ThreadLocalRandom.current());
                // test bug: the following is not guaranteed and not true in JDK8
                //                assertNotSame(current, threadLocalRandom.get());
                rand.set(current.nextLong());
                threadLocalRandom.set(current);
            }};

        Thread first = newStartedThread(getRandomState);
        awaitTermination(first);
        firstRand = rand.get();
        firstThreadLocalRandom = threadLocalRandom.get();

        for (int i = 0; i < NCALLS; i++) {
            Thread t = newStartedThread(getRandomState);
            awaitTermination(t);
            if (firstRand != rand.get())
                return;
        }
        fail("all threads generate the same pseudo-random sequence");
    }

}
Revision:	1.24
Committed:	Sat Dec 10 12:39:15 2016 UTC (7 years, 5 months ago) by jsr166
Branch:	MAIN
Changes since 1.23:	+8 -3 lines
Log Message:	testNext: make test work with pre-jdk9
#	User	Rev	Content
1	dl	1.1	/*
2			* Written by Doug Lea with assistance from members of JCP JSR-166
3			* Expert Group and released to the public domain, as explained at
4	jsr166	1.8	* http://creativecommons.org/publicdomain/zero/1.0/
5	dl	1.1	*/
6	jsr166	1.20
7	jsr166	1.10	import java.util.concurrent.ThreadLocalRandom;
8	jsr166	1.11	import java.util.concurrent.atomic.AtomicLong;
9			import java.util.concurrent.atomic.AtomicReference;
10	dl	1.1
11	jsr166	1.20	import junit.framework.Test;
12			import junit.framework.TestSuite;
13
14	dl	1.1	public class ThreadLocalRandomTest extends JSR166TestCase {
15
16			public static void main(String[] args) {
17	jsr166	1.21	main(suite(), args);
18	dl	1.1	}
19			public static Test suite() {
20	jsr166	1.4	return new TestSuite(ThreadLocalRandomTest.class);
21	dl	1.1	}
22
23	jsr166	1.13	/*
24	dl	1.1	* Testing coverage notes:
25	jsr166	1.2	*
26	dl	1.1	* We don't test randomness properties, but only that repeated
27			* calls, up to NCALLS tries, produce at least one different
28			* result. For bounded versions, we sample various intervals
29			* across multiples of primes.
30			*/
31
32	jsr166	1.14	// max numbers of calls to detect getting stuck on one value
33	dl	1.1	static final int NCALLS = 10000;
34
35			// max sampled int bound
36			static final int MAX_INT_BOUND = (1 << 28);
37
38	jsr166	1.14	// max sampled long bound
39	dl	1.1	static final long MAX_LONG_BOUND = (1L << 42);
40
41	dl	1.15	// Number of replications for other checks
42			static final int REPS = 20;
43
44	dl	1.1	/**
45			* setSeed throws UnsupportedOperationException
46			*/
47			public void testSetSeed() {
48			try {
49			ThreadLocalRandom.current().setSeed(17);
50	jsr166	1.3	shouldThrow();
51	jsr166	1.5	} catch (UnsupportedOperationException success) {}
52	dl	1.1	}
53
54			/**
55	jsr166	1.22	* Repeated calls to next (only accessible via reflection) produce
56			* at least two distinct results, and repeated calls produce all
57			* possible values.
58			*/
59			public void testNext() throws ReflectiveOperationException {
60			ThreadLocalRandom rnd = ThreadLocalRandom.current();
61	jsr166	1.23	final java.lang.reflect.Method m;
62	jsr166	1.22	try {
63	jsr166	1.23	m = ThreadLocalRandom.class.getDeclaredMethod(
64	jsr166	1.22	"next", new Class[] { int.class });
65			m.setAccessible(true);
66	jsr166	1.24	} catch (SecurityException acceptable) {
67			// Security manager may deny access
68	jsr166	1.23	return;
69	jsr166	1.24	} catch (Exception ex) {
70			// jdk9 module system may deny access
71			if (ex.getClass().getSimpleName()
72			.equals("InaccessibleObjectException"))
73			return;
74			throw ex;
75	jsr166	1.23	}
76	jsr166	1.22
77	jsr166	1.23	int i;
78			{
79			int val = new java.util.Random().nextInt(4);
80			for (i = 0; i < NCALLS; i++) {
81			int q = (int) m.invoke(rnd, new Object[] { 2 });
82			if (val == q) break;
83	jsr166	1.22	}
84	jsr166	1.23	assertTrue(i < NCALLS);
85			}
86	jsr166	1.22
87	jsr166	1.23	{
88			int r = (int) m.invoke(rnd, new Object[] { 3 });
89			for (i = 0; i < NCALLS; i++) {
90			int q = (int) m.invoke(rnd, new Object[] { 3 });
91			assertTrue(q < (1<<3));
92			if (r != q) break;
93	jsr166	1.22	}
94	jsr166	1.23	assertTrue(i < NCALLS);
95			}
96	jsr166	1.22	}
97
98			/**
99	jsr166	1.14	* Repeated calls to nextInt produce at least two distinct results
100	dl	1.1	*/
101			public void testNextInt() {
102			int f = ThreadLocalRandom.current().nextInt();
103			int i = 0;
104			while (i < NCALLS && ThreadLocalRandom.current().nextInt() == f)
105			++i;
106			assertTrue(i < NCALLS);
107			}
108
109			/**
110	jsr166	1.14	* Repeated calls to nextLong produce at least two distinct results
111	dl	1.1	*/
112			public void testNextLong() {
113			long f = ThreadLocalRandom.current().nextLong();
114			int i = 0;
115			while (i < NCALLS && ThreadLocalRandom.current().nextLong() == f)
116			++i;
117			assertTrue(i < NCALLS);
118			}
119
120			/**
121	jsr166	1.14	* Repeated calls to nextBoolean produce at least two distinct results
122	dl	1.1	*/
123			public void testNextBoolean() {
124			boolean f = ThreadLocalRandom.current().nextBoolean();
125			int i = 0;
126			while (i < NCALLS && ThreadLocalRandom.current().nextBoolean() == f)
127			++i;
128			assertTrue(i < NCALLS);
129			}
130
131			/**
132	jsr166	1.14	* Repeated calls to nextFloat produce at least two distinct results
133	dl	1.1	*/
134			public void testNextFloat() {
135			float f = ThreadLocalRandom.current().nextFloat();
136			int i = 0;
137			while (i < NCALLS && ThreadLocalRandom.current().nextFloat() == f)
138			++i;
139			assertTrue(i < NCALLS);
140			}
141
142			/**
143	jsr166	1.14	* Repeated calls to nextDouble produce at least two distinct results
144	dl	1.1	*/
145			public void testNextDouble() {
146			double f = ThreadLocalRandom.current().nextDouble();
147	jsr166	1.14	int i = 0;
148	dl	1.1	while (i < NCALLS && ThreadLocalRandom.current().nextDouble() == f)
149			++i;
150			assertTrue(i < NCALLS);
151			}
152
153			/**
154	jsr166	1.14	* Repeated calls to nextGaussian produce at least two distinct results
155	dl	1.1	*/
156			public void testNextGaussian() {
157			double f = ThreadLocalRandom.current().nextGaussian();
158			int i = 0;
159			while (i < NCALLS && ThreadLocalRandom.current().nextGaussian() == f)
160			++i;
161			assertTrue(i < NCALLS);
162			}
163
164			/**
165	jsr166	1.19	* nextInt(non-positive) throws IllegalArgumentException
166	dl	1.1	*/
167	jsr166	1.19	public void testNextIntBoundNonPositive() {
168			ThreadLocalRandom rnd = ThreadLocalRandom.current();
169			for (int bound : new int[] { 0, -17, Integer.MIN_VALUE }) {
170			try {
171			rnd.nextInt(bound);
172			shouldThrow();
173			} catch (IllegalArgumentException success) {}
174			}
175	dl	1.1	}
176
177			/**
178	jsr166	1.14	* nextInt(least >= bound) throws IllegalArgumentException
179	dl	1.1	*/
180			public void testNextIntBadBounds() {
181	jsr166	1.19	int[][] badBoundss = {
182			{ 17, 2 },
183			{ -42, -42 },
184			{ Integer.MAX_VALUE, Integer.MIN_VALUE },
185			};
186			ThreadLocalRandom rnd = ThreadLocalRandom.current();
187			for (int[] badBounds : badBoundss) {
188			try {
189			rnd.nextInt(badBounds[0], badBounds[1]);
190			shouldThrow();
191			} catch (IllegalArgumentException success) {}
192			}
193	dl	1.1	}
194
195			/**
196			* nextInt(bound) returns 0 <= value < bound;
197	jsr166	1.14	* repeated calls produce at least two distinct results
198	dl	1.1	*/
199			public void testNextIntBounded() {
200			// sample bound space across prime number increments
201			for (int bound = 2; bound < MAX_INT_BOUND; bound += 524959) {
202			int f = ThreadLocalRandom.current().nextInt(bound);
203			assertTrue(0 <= f && f < bound);
204			int i = 0;
205			int j;
206	jsr166	1.2	while (i < NCALLS &&
207	dl	1.1	(j = ThreadLocalRandom.current().nextInt(bound)) == f) {
208			assertTrue(0 <= j && j < bound);
209			++i;
210			}
211			assertTrue(i < NCALLS);
212			}
213			}
214
215			/**
216			* nextInt(least, bound) returns least <= value < bound;
217	jsr166	1.14	* repeated calls produce at least two distinct results
218	dl	1.1	*/
219			public void testNextIntBounded2() {
220			for (int least = -15485863; least < MAX_INT_BOUND; least += 524959) {
221			for (int bound = least + 2; bound > least && bound < MAX_INT_BOUND; bound += 49979687) {
222			int f = ThreadLocalRandom.current().nextInt(least, bound);
223			assertTrue(least <= f && f < bound);
224			int i = 0;
225			int j;
226	jsr166	1.2	while (i < NCALLS &&
227	dl	1.1	(j = ThreadLocalRandom.current().nextInt(least, bound)) == f) {
228			assertTrue(least <= j && j < bound);
229			++i;
230			}
231			assertTrue(i < NCALLS);
232			}
233			}
234			}
235
236			/**
237	jsr166	1.19	* nextLong(non-positive) throws IllegalArgumentException
238	dl	1.1	*/
239	jsr166	1.19	public void testNextLongBoundNonPositive() {
240			ThreadLocalRandom rnd = ThreadLocalRandom.current();
241			for (long bound : new long[] { 0L, -17L, Long.MIN_VALUE }) {
242			try {
243			rnd.nextLong(bound);
244			shouldThrow();
245			} catch (IllegalArgumentException success) {}
246			}
247	dl	1.1	}
248
249			/**
250	jsr166	1.14	* nextLong(least >= bound) throws IllegalArgumentException
251	dl	1.1	*/
252			public void testNextLongBadBounds() {
253	jsr166	1.19	long[][] badBoundss = {
254			{ 17L, 2L },
255			{ -42L, -42L },
256			{ Long.MAX_VALUE, Long.MIN_VALUE },
257			};
258			ThreadLocalRandom rnd = ThreadLocalRandom.current();
259			for (long[] badBounds : badBoundss) {
260			try {
261			rnd.nextLong(badBounds[0], badBounds[1]);
262			shouldThrow();
263			} catch (IllegalArgumentException success) {}
264			}
265	dl	1.1	}
266
267			/**
268			* nextLong(bound) returns 0 <= value < bound;
269	jsr166	1.14	* repeated calls produce at least two distinct results
270	dl	1.1	*/
271			public void testNextLongBounded() {
272			for (long bound = 2; bound < MAX_LONG_BOUND; bound += 15485863) {
273			long f = ThreadLocalRandom.current().nextLong(bound);
274			assertTrue(0 <= f && f < bound);
275			int i = 0;
276			long j;
277	jsr166	1.2	while (i < NCALLS &&
278	dl	1.1	(j = ThreadLocalRandom.current().nextLong(bound)) == f) {
279			assertTrue(0 <= j && j < bound);
280			++i;
281			}
282			assertTrue(i < NCALLS);
283			}
284			}
285
286			/**
287			* nextLong(least, bound) returns least <= value < bound;
288	jsr166	1.14	* repeated calls produce at least two distinct results
289	dl	1.1	*/
290			public void testNextLongBounded2() {
291			for (long least = -86028121; least < MAX_LONG_BOUND; least += 982451653L) {
292			for (long bound = least + 2; bound > least && bound < MAX_LONG_BOUND; bound += Math.abs(bound * 7919)) {
293			long f = ThreadLocalRandom.current().nextLong(least, bound);
294			assertTrue(least <= f && f < bound);
295			int i = 0;
296			long j;
297	jsr166	1.2	while (i < NCALLS &&
298	dl	1.1	(j = ThreadLocalRandom.current().nextLong(least, bound)) == f) {
299			assertTrue(least <= j && j < bound);
300			++i;
301			}
302			assertTrue(i < NCALLS);
303			}
304			}
305			}
306
307			/**
308	jsr166	1.19	* nextDouble(non-positive) throws IllegalArgumentException
309			*/
310			public void testNextDoubleBoundNonPositive() {
311			ThreadLocalRandom rnd = ThreadLocalRandom.current();
312			double[] badBounds = {
313			0.0d,
314			-17.0d,
315			-Double.MIN_VALUE,
316			Double.NEGATIVE_INFINITY,
317			Double.NaN,
318			};
319			for (double bound : badBounds) {
320			try {
321			rnd.nextDouble(bound);
322			shouldThrow();
323			} catch (IllegalArgumentException success) {}
324			}
325			}
326
327			/**
328	dl	1.1	* nextDouble(least, bound) returns least <= value < bound;
329	jsr166	1.14	* repeated calls produce at least two distinct results
330	dl	1.1	*/
331			public void testNextDoubleBounded2() {
332			for (double least = 0.0001; least < 1.0e20; least *= 8) {
333			for (double bound = least * 1.001; bound < 1.0e20; bound *= 16) {
334			double f = ThreadLocalRandom.current().nextDouble(least, bound);
335			assertTrue(least <= f && f < bound);
336			int i = 0;
337			double j;
338	jsr166	1.2	while (i < NCALLS &&
339	dl	1.1	(j = ThreadLocalRandom.current().nextDouble(least, bound)) == f) {
340			assertTrue(least <= j && j < bound);
341			++i;
342			}
343			assertTrue(i < NCALLS);
344			}
345			}
346			}
347
348	jsr166	1.11	/**
349			* Different threads produce different pseudo-random sequences
350			*/
351			public void testDifferentSequences() {
352			// Don't use main thread's ThreadLocalRandom - it is likely to
353			// be polluted by previous tests.
354			final AtomicReference<ThreadLocalRandom> threadLocalRandom =
355			new AtomicReference<ThreadLocalRandom>();
356			final AtomicLong rand = new AtomicLong();
357
358			long firstRand = 0;
359			ThreadLocalRandom firstThreadLocalRandom = null;
360
361	jsr166	1.18	Runnable getRandomState = new CheckedRunnable() {
362	jsr166	1.11	public void realRun() {
363			ThreadLocalRandom current = ThreadLocalRandom.current();
364			assertSame(current, ThreadLocalRandom.current());
365	dl	1.12	// test bug: the following is not guaranteed and not true in JDK8
366			// assertNotSame(current, threadLocalRandom.get());
367	jsr166	1.11	rand.set(current.nextLong());
368			threadLocalRandom.set(current);
369			}};
370
371			Thread first = newStartedThread(getRandomState);
372			awaitTermination(first);
373			firstRand = rand.get();
374			firstThreadLocalRandom = threadLocalRandom.get();
375
376			for (int i = 0; i < NCALLS; i++) {
377			Thread t = newStartedThread(getRandomState);
378			awaitTermination(t);
379			if (firstRand != rand.get())
380			return;
381			}
382			fail("all threads generate the same pseudo-random sequence");
383			}
384
385	dl	1.1	}