我是否需要对invokeAll调用的结果进行同步?

private final ExecutorService pool = ...;

// A single task to be performed concurrently with other tasks.
private class WorkHorse implements Callable<Void> {
    private final Collection<X> collect;

    public WorkHorse(Collection<X> collect, ...) {
        this.collect = collect;
    }

    public Void call() {
        for (...) {
            // do work

            synchronized (this.collect) {
                this.collect.add(result);
            }
        }
        return null;
    }
}

// Uses multiple concurrent tasks to compute its result list.
public Collection<X> getResults() {
    // this list is supposed to hold the results
    final Collection<X> collect = new LinkedList<X>();

    final List<WorkHorse> tasks = Arrays.asList(  
        new WorkHorse(collect, ...), new WorkHorse(collect, ...), ...);
    this.pool.invokeAll(tasks);

    // ## A ##
    synchronized (collect) {
        return collect;
    }
}

我真的需要这个吗 synchronized 在“#####”执行与辅助任务中的修改操作的“发生在之前”关系?或者,我可以依赖于之后发生的所有写入操作吗 invokeAll 返回并对控制线程可见吗?还有什么原因,为什么我不应该从它自己的内部返回结果集合 块