可调用对象的执行顺序不一致答案

【问题标题】：Execution order of callables is not consistent可调用对象的执行顺序不一致
【发布时间】：2018-12-21 16:11:29
【问题描述】：

我有这段代码，我在其中执行一组可调用对象，我需要一组来完成所有工作，然后再触发下一组。这段代码似乎工作正常，但有时下一组会在时间之前开始运行。这里有什么问题？

private void executeSubGraph(QuestExecutionContext ctx, Set<Activity> subGraph, int progressAfterRan) {
    ExecutorService pool = Executors.newFixedThreadPool(16);
    subGraph.forEach(a -> {
        ActivityRunner<? extends Activity> runner = activityRunnerFactory.getRunner(ctx, a);
        if (runner != null) {
            Callable<List<PortValuePart>> runnerCallable = () -> {
                try {
                    LOG.info("Running {} in {}", a, a.getClass() );
                    List<PortValuePart> result = runner.call();
                    LOG.info("Result of {} in {} is {}", a, a.getClass(), result);
                    if (result != null) {
                        result.forEach(r -> resultProcessor.processResult(new PortValuePartEnvelope(r)));
                    }
                    return result;
                } catch (Exception e) {
                    LOG.warn("Exception for {} in {}", a, runner.getClass(), e);
                    resultProcessor.processResult(Progress.failed(ctx.getId(), e));
                    throw new RuntimeException(e);
                }
            };
            Future<List<PortValuePart>> p = pool.submit(runnerCallable);
        } else {
            LOG.warn("No runner found for activity {}", a);
            resultProcessor.processResult(Progress.failed(ctx.getId(), new RuntimeException("No runner found for activity " + a)));
            throw new RuntimeException("No runner found for activity " + a);
        }
    });

    pool.shutdown();

    try {
        pool.awaitTermination(WAIT_TIME_MILLIS, TimeUnit.MILLISECONDS);
        resultProcessor.processResult(Progress.running(ctx.getId(), progressAfterRan));
    } catch (InterruptedException e) {
        throw new PlatformException("Execution interrupted.");
    }
}

【问题讨论】：

标签： java multithreading concurrency callable

【解决方案1】：

请注意，ExecutorService.awaitTermination 在超时时不会抛出异常；它只返回false。如果您想确保下一个调用不会与这些调用同时运行，您可能应该使用返回值，如果耗时太长，可能会抛出异常（并终止任务）。

【讨论】：