1 |
dl |
1.1 |
/* |
2 |
|
|
* Written by Doug Lea with assistance from members of JCP JSR-166 |
3 |
dl |
1.3 |
* Expert Group and released to the public domain, as explained at |
4 |
|
|
* http://creativecommons.org/licenses/publicdomain |
5 |
dl |
1.1 |
*/ |
6 |
|
|
|
7 |
|
|
import java.util.concurrent.*; |
8 |
|
|
import java.util.concurrent.locks.*; |
9 |
|
|
import java.util.*; |
10 |
|
|
|
11 |
|
|
public final class SimpleSemaphoreLoops { |
12 |
|
|
static final ExecutorService pool = Executors.newCachedThreadPool(); |
13 |
|
|
static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom(); |
14 |
|
|
static boolean print = false; |
15 |
|
|
static int iters = 10000000; |
16 |
|
|
|
17 |
|
|
public static void main(String[] args) throws Exception { |
18 |
|
|
int maxThreads = 100; |
19 |
jsr166 |
1.4 |
if (args.length > 0) |
20 |
dl |
1.1 |
maxThreads = Integer.parseInt(args[0]); |
21 |
|
|
|
22 |
|
|
print = true; |
23 |
|
|
|
24 |
|
|
int reps = 2; |
25 |
|
|
for (int i = 1; i <= maxThreads; i += (i+1) >>> 1) { |
26 |
|
|
int n = reps; |
27 |
|
|
if (reps > 1) --reps; |
28 |
|
|
while (n-- > 0) { |
29 |
|
|
System.out.print("Threads: " + i); |
30 |
|
|
new SemaphoreLoop(i).test(); |
31 |
|
|
Thread.sleep(100); |
32 |
|
|
} |
33 |
|
|
} |
34 |
|
|
pool.shutdown(); |
35 |
|
|
} |
36 |
|
|
|
37 |
|
|
static final class SemaphoreLoop implements Runnable { |
38 |
|
|
private int v = rng.next(); |
39 |
|
|
private volatile int result = 17; |
40 |
|
|
private final Semaphore lock = new Semaphore(1, false); |
41 |
|
|
private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer(); |
42 |
|
|
private final CyclicBarrier barrier; |
43 |
|
|
private final int nthreads; |
44 |
|
|
private volatile int readBarrier; |
45 |
|
|
SemaphoreLoop(int nthreads) { |
46 |
|
|
this.nthreads = nthreads; |
47 |
|
|
barrier = new CyclicBarrier(nthreads+1, timer); |
48 |
|
|
} |
49 |
|
|
|
50 |
|
|
final void test() throws Exception { |
51 |
jsr166 |
1.4 |
for (int i = 0; i < nthreads; ++i) |
52 |
dl |
1.1 |
pool.execute(this); |
53 |
|
|
barrier.await(); |
54 |
|
|
barrier.await(); |
55 |
|
|
if (print) { |
56 |
|
|
long time = timer.getTime(); |
57 |
|
|
long tpi = time / ((long)iters * nthreads); |
58 |
|
|
System.out.print("\t" + LoopHelpers.rightJustify(tpi) + " ns per lock"); |
59 |
|
|
double secs = (double)(time) / 1000000000.0; |
60 |
|
|
System.out.println("\t " + secs + "s run time"); |
61 |
|
|
} |
62 |
|
|
|
63 |
|
|
int r = result; |
64 |
|
|
if (r == 0) // avoid overoptimization |
65 |
|
|
System.out.println("useless result: " + r); |
66 |
|
|
} |
67 |
|
|
|
68 |
|
|
public final void run() { |
69 |
|
|
final Semaphore lock = this.lock; |
70 |
|
|
try { |
71 |
jsr166 |
1.4 |
barrier.await(); |
72 |
dl |
1.1 |
int sum = v + 1; |
73 |
|
|
int x = 0; |
74 |
|
|
int n = iters; |
75 |
|
|
while (n-- > 0) { |
76 |
|
|
lock.acquireUninterruptibly(); |
77 |
|
|
int k = (sum & 3); |
78 |
|
|
if (k > 0) { |
79 |
|
|
x = v; |
80 |
|
|
while (k-- > 0) |
81 |
dl |
1.2 |
x = LoopHelpers.compute6(x); |
82 |
dl |
1.1 |
v = x; |
83 |
|
|
} |
84 |
|
|
else x = sum + 1; |
85 |
|
|
lock.release(); |
86 |
|
|
if ((x += readBarrier) == 0) |
87 |
|
|
++readBarrier; |
88 |
|
|
for (int l = x & 7; l > 0; --l) |
89 |
dl |
1.2 |
sum += LoopHelpers.compute6(sum); |
90 |
jsr166 |
1.4 |
} |
91 |
dl |
1.1 |
barrier.await(); |
92 |
|
|
result += sum; |
93 |
|
|
} |
94 |
jsr166 |
1.4 |
catch (Exception ie) { |
95 |
|
|
return; |
96 |
dl |
1.1 |
} |
97 |
|
|
} |
98 |
|
|
} |
99 |
|
|
} |