Examples of java.util.concurrent.atomic.LongAdder

• java.util.concurrent.atomic.LongAdder
  One or more variables that together maintain an initially zero {@code long} sum. When updates (method {@link #add}) are contended across threads, the set of variables may grow dynamically to reduce contention. Method {@link #sum} (or, equivalently, {@link #longValue}) returns the current total combined across the variables maintaining the sum.

  This class is usually preferable to {@link AtomicLong} whenmultiple threads update a common sum that is used for purposes such as collecting statistics, not for fine-grained synchronization control. Under low update contention, the two classes have similar characteristics. But under high contention, expected throughput of this class is significantly higher, at the expense of higher space consumption.

  LongAdders can be used with a {@link java.util.concurrent.ConcurrentHashMap} to maintain a scalablefrequency map (a form of histogram or multiset). For example, to add a count to a {@code ConcurrentHashMap freqs}, initializing if not already present, you can use {@code freqs.computeIfAbsent(k -> new LongAdder()).increment();}

  This class extends {@link Number}, but does not define methods such as {@code equals}, {@code hashCode} and {@code compareTo} because instances are expected to be mutated, and so arenot useful as collection keys. @since 1.8 @author Doug Lea

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