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  1.  
  2. import java.util.concurrent.TimeUnit;
  3. import java.util.concurrent.atomic.AtomicLong;
  4.  
  5.  
  6. class Ideone {
  7. 	public static void main(String[] args) {
  8. 		final int n = 100;
  9. 		final int k = 100000;
  10. 		long elap;
  11.  
  12. 		elap = 0;
  13. 		for (int i = 0; i < n; i++) {
  14. 			elap += testPlain(k);
  15. 		}
  16. 		System.out.printf("for (1 .. %d) { for (1 .. %d) <count with %s> }: avg=%d (total=%d) in millis%n", n, k, "+=", TimeUnit.MILLISECONDS.convert(elap / n, TimeUnit.NANOSECONDS), TimeUnit.MILLISECONDS.convert(elap, TimeUnit.NANOSECONDS));
  17.  
  18. 		elap = 0;
  19. 		for (int i = 0; i < n; i++) {
  20. 			elap += testSynchronized(k);
  21. 		}
  22. 		System.out.printf("for (1 .. %d) { for (1 .. %d) <count with %s> }: avg=%d (total=%d) in millis%n", n, k, "synchronized(+=)", TimeUnit.MILLISECONDS.convert(elap / n, TimeUnit.NANOSECONDS), TimeUnit.MILLISECONDS.convert(elap, TimeUnit.NANOSECONDS));
  23.  
  24. 		elap = 0;
  25. 		for (int i = 0; i < n; i++) {
  26. 			elap += testAtomicLong(k);
  27. 		}
  28. 		System.out.printf("for (1 .. %d) { for (1 .. %d) <count with %s> }: avg=%d (total=%d) in millis%n", n, k, "AtomicLong#addAndGet", TimeUnit.MILLISECONDS.convert(elap / n, TimeUnit.NANOSECONDS), TimeUnit.MILLISECONDS.convert(elap, TimeUnit.NANOSECONDS));
  29. 	}
  30.  
  31. 	static void nullmethod(final long l) {
  32.  
  33. 	}
  34.  
  35. 	static long testPlain(final int n) {
  36. 		final long begin = System.nanoTime();
  37. 		long sum = 0;
  38. 		for (int i = 0; i < n; i++) {
  39. 			sum += i;
  40. 		}
  41. 		nullmethod(sum);
  42. 		return System.nanoTime() - begin;
  43. 	}
  44.  
  45. 	static long testSynchronized(final int n) {
  46. 		final long begin = System.nanoTime();
  47. 		long sum = 0;
  48. 		for (int i = 0; i < n; i++) {
  49. 			synchronized (Ideone.class) {
  50. 				sum += i;
  51. 			}
  52. 		}
  53. 		nullmethod(sum);
  54. 		return System.nanoTime() - begin;
  55. 	}
  56.  
  57. 	static long testAtomicLong(final int n) {
  58. 		final long begin = System.nanoTime();
  59. 		AtomicLong sum = new AtomicLong();
  60. 		for (int i = 0; i < n; i++) {
  61. 			sum.addAndGet(i);
  62. 		}
  63. 		nullmethod(sum.get());
  64. 		return System.nanoTime() - begin;
  65. 	}
  66.  
  67. }
  68.  
Success #stdin #stdout 0.5s 380224KB
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Standard input is empty
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for (1 .. 100) { for (1 .. 100000) <count with +=> }: avg=0 (total=18) in millis
for (1 .. 100) { for (1 .. 100000) <count with synchronized(+=)> }: avg=2 (total=249) in millis
for (1 .. 100) { for (1 .. 100000) <count with AtomicLong#addAndGet> }: avg=1 (total=165) in millis
https://ideone.com/P64Io2
language:
Java (12.0.1)
created:
9 years ago
visibility:
public

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