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858天前import java.util.concurrent.Callable; |
import java.util.concurrent.CompletionService; |
import java.util.concurrent.ExecutionException; |
import java.util.concurrent.ExecutorCompletionService; |
import java.util.concurrent.ExecutorService; |
import java.util.concurrent.Executors; |
public class ConcurrentCalculator { |
private ExecutorService exec; |
private CompletionService<Long> completionService; |
private int cpuCoreNumber; |
class SumCalculator implements Callable<Long> { |
private int[] numbers; |
private int start; |
private int end; |
public SumCalculator (final int[] numbers, int start, int end) { |
this.numbers = numbers; |
this.start = start; |
this.end = end; |
} |
public Long call() throws Exception { |
Long sum = 0l; |
for (int i = start; i < end; i++) { |
sum += numbers[i]; |
} |
return sum; |
} |
} |
public ConcurrentCalculator() { |
cpuCoreNumber = Runtime.getRuntime().availableProcessors(); |
exec = Executors.newFixedThreadPool (cpuCoreNumber); |
completionService = new ExecutorCompletionService<Long> (exec); |
} |
public Long sum (final int[] numbers) { |
for (int i = 0; i < cpuCoreNumber; i++) { |
int increment = numbers.length / cpuCoreNumber + 1; |
int start = increment * i; |
int end = increment * i + increment; |
if (end > numbers.length) { |
end = numbers.length; |
} |
SumCalculator subCalc = new SumCalculator (numbers, start, end); |
if (!exec.isShutdown() ) { |
completionService.submit (subCalc); |
} |
} |
return getResult(); |
} |
public Long getResult() { |
Long result = 0l; |
for (int i = 0; i < cpuCoreNumber; i++) { |
try { |
Long subSum = completionService.take().get(); |
result += subSum; |
} catch (InterruptedException e) { |
e.printStackTrace(); |
} catch (ExecutionException e) { |
e.printStackTrace(); |
} |
} |
return result; |
} |
public void close() { |
exec.shutdown(); |
} |
public static void main (String[] args) { |
int[] numbers = new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 34 }; |
ConcurrentCalculator calc = new ConcurrentCalculator(); |
Long sum = calc.sum (numbers); |
System.out.println (sum); |
calc.close(); |
} |
} |
