可以以线程安全的方式安全地增加BigInteger,也许使用AtomicReference,没有锁定？

bow*_*ore 13

可以使用AtomicReference这里的快速草稿:

public final class AtomicBigInteger {

    private final AtomicReference<BigInteger> valueHolder = new AtomicReference<>();

    public AtomicBigInteger(BigInteger bigInteger) {
        valueHolder.set(bigInteger);
    }

    public BigInteger incrementAndGet() {
        for (; ; ) {
            BigInteger current = valueHolder.get();
            BigInteger next = current.add(BigInteger.ONE);
            if (valueHolder.pareAndSet(current, next)) {
                return next;
            }
        }
    }
}

它基本上是AtomicLong代码的副本 incrementAndGet()

mko*_*bit 5

使用Java 8 中引入的aumulateAndGet或 ，这变得更易于管理和更容易理解getAndAumulate。 这些允许您通过提供一个累加器函数来自动更新值，该函数将值设置为函数的结果，并且还返回先前或计算出的结果取决于你需要什么。这是该类的示例，然后是我编写的使用它的简单示例：

import java.math.BigInteger;
import java.util.Objects;
import java.util.concurrent.atomic.AtomicReference;

public final class AtomicBigInteger {

  private final AtomicReference<BigInteger> bigInteger;

  public AtomicBigInteger(final BigInteger bigInteger) {
    this.bigInteger = new AtomicReference<>(Objects.requireNonNull(bigInteger));
  }

  // Method references left out for demonstration purposes
  public BigInteger incrementAndGet() {
    return bigInteger.aumulateAndGet(BigInteger.ONE, (previous, x) -> previous.add(x));
  }

  public BigInteger getAndIncrement() {
    return bigInteger.getAndAumulate(BigInteger.ONE, (previous, x) -> previous.add(x));
  }

  public BigInteger get() {
    return bigInteger.get();
  }
}

一个使用它的例子：

import java.math.BigInteger;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

public class ABIExample {

  private static final int AVAILABLE_PROCS = Runtime.getRuntime().availableProcessors();
  private static final int INCREMENT_AMOUNT = 2_500_000;
  private static final int TASK_AMOUNT = AVAILABLE_PROCS * 2;
  private static final BigInteger EXPECTED_VALUE = BigInteger.valueOf(INCREMENT_AMOUNT)
                                                             .multiply(BigInteger
                                                                           .valueOf(TASK_AMOUNT));

  public static void main(String[] args)
      throws InterruptedException, ExecutionException {
    System.out.println("Available processors: " + AVAILABLE_PROCS);


    final ExecutorService executorService = Executors
        .newFixedThreadPool(Runtime.getRuntime().availableProcessors());

    final AtomicBigInteger atomicBigInteger = new AtomicBigInteger(BigInteger.ZERO);

    final List<Callable<Void>> incrementTasks =  IntStream.rangeClosed(1, TASK_AMOUNT)
             .mapToObj(i -> incrementTask(i, atomicBigInteger))
             .collect(Collectors.toList());
    final List<Future<Void>> futures = executorService.invokeAll(incrementTasks);
    for (Future<Void> future : futures) {
      future.get();
    }
    executorService.shutdown();
    executorService.awaitTermination(30, TimeUnit.SECONDS);
    System.out.println("Final value: " + atomicBigInteger.get());
    final boolean areEqual = EXPECTED_VALUE.equals(atomicBigInteger.get());
    System.out.println("Does final value equal expected? - " + areEqual);
  }

  private static Callable<Void> incrementTask(
      final int taskNumber,
      final AtomicBigInteger atomicBigInteger
  ) {
    return () -> {
      for (int increment = 0; increment < INCREMENT_AMOUNT; increment++) {
        atomicBigInteger.incrementAndGet();
      }
      System.out.println("Task #" + taskNumber + " Completed");
      return null;
    };

  }
}

以及在我的机器上运行示例的输出：

Available processors: 8
Task #3 Completed
Task #8 Completed
Task #7 Completed
Task #6 Completed
Task #5 Completed
Task #2 Completed
Task #4 Completed
Task #1 Completed
Task #9 Completed
Task #10 Completed
Task #11 Completed
Task #13 Completed
Task #16 Completed
Task #12 Completed
Task #14 Completed
Task #15 Completed
Final value: 80000000
Does final value equal expected? - true