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FlexDoc/Javadoc 2.0 Demo Java Doc |
For a classic example, here is a task computing Fibonacci numbers:
class Fibonacci extends RecursiveTask<Integer> {
final int n;
Fibonacci(int n) { this.n = n; }
protected Integer compute() {
if (n <= 1)
return n;
Fibonacci f1 = new Fibonacci(n - 1);
f1.fork();
Fibonacci f2 = new Fibonacci(n - 2);
return f2.compute() + f1.join();
}
}
However, besides being a dumb way to compute Fibonacci functions
(there is a simple fast linear algorithm that you'd use in
practice), this is likely to perform poorly because the smallest
subtasks are too small to be worthwhile splitting up. Instead, as
is the case for nearly all fork/join applications, you'd pick some
minimum granularity size (for example 10 here) for which you always
sequentially solve rather than subdividing.Constructor Summary |
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Constructor for subclasses to call.
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Method Summary |
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protected abstract V |
compute()
The main computation performed by this task.
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protected final boolean |
exec()
Implements execution conventions for RecursiveTask.
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final V |
Returns the result that would be returned by ForkJoinTask.join(), even
if this task completed abnormally, or null if this task
is not known to have been completed.
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protected final void |
setRawResult(V value)
Forces the given value to be returned as a result.
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Methods inherited from class java.util.concurrent.ForkJoinTask |
adapt, adapt, adapt, cancel, compareAndSetForkJoinTaskTag, complete, completeExceptionally, fork, get, get, getException, getForkJoinTaskTag, getPool, getQueuedTaskCount, getSurplusQueuedTaskCount, helpQuiesce, inForkJoinPool, invoke, invokeAll, invokeAll, invokeAll, isCancelled, isCompletedAbnormally, isCompletedNormally, isDone, join, peekNextLocalTask, pollNextLocalTask, pollSubmission, pollTask, quietlyComplete, quietlyInvoke, quietlyJoin, reinitialize, setForkJoinTaskTag, tryUnfork |
Methods inherited from class java.lang.Object |
public RecursiveTask |
() |
protected abstract V compute |
() |
public final V getRawResult |
() |
protected final void setRawResult |
(V value) |
protected final boolean exec |
() |
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FlexDoc/Javadoc 2.0 Demo Java Doc |