Service.ShutdownNow（）未终止线程

Question

            ExecutorService service = Executors.newSingleThreadExecutor();
            Future<Object> prediction = null;
            try {
              prediction = service.submit(() -> {
                // Execute the requested Document Prediction Engine against the XML Document.
                return executeEngine(tenantId, appId, engine, document, predictionParams == null ? new HashMap<>() : new HashMap<>(predictionParams)).get();
              });
              predictionResult = prediction != null ? (PredictionResult) prediction.get(Long.parseLong(System.getProperty(IDR_INTERNAL_TIMEOUT, "30000")),
                      TimeUnit.MILLISECONDS) : null;
              } catch (TimeoutException e) {
              if (prediction != null) {
                LOGGER.debug("Task was cancelled with a {} status", (prediction.cancel(true) ? " successful" : " failure"));
              }
              ExpenseMetrics.internalPredictionTimeout.inc();
              String message = "Prediction took more than allowed milliseconds: " + Long.parseLong(System.getProperty(IDR_INTERNAL_TIMEOUT, "30000")) +
                " fileName: "+ documentFile.getFileName();
              
              if (service != null && !service.isShutdown()) {
                service.shutdownNow();
              }
              service = null;
              throw new IDRExmClientException(message, requestId, ErrorCode.INTERNAL_TIMEOUT);
            } 
            if (service != null && !service.isShutdown()) {
              service.shutdownNow();
            }
            service = null;

List<Callable<Void>> taskList = new ArrayList<Callable<Void>>();
taskList.add(callable1);
taskList.add(callable2);    
ExecutorService executor = null;
List<Future<Void>> futures = null;
long s = System.currentTimeMillis();
try {
  executor = Executors.newFixedThreadPool(THREAD_POOL);
  futures = executor.invokeAll(taskList);    
  executor.shutdown();
  if (!executor.awaitTermination(TOLERANCE_MINUTES, TimeUnit.MINUTES)) {                
    LOGGER.warn("Document predict thread took more than {} minutes to shutdown", TOLERANCE_MINUTES);
    executor.shutdownNow();
  }
} catch (InterruptedException iex) {
  LOGGER.error("Document predict thread was interrupted", iex);
} finally {
  cancelFutures("Predict", futures);
  LOGGER.debug("Document predict thread took: {}", (System.currentTimeMillis() - s));
  if (executor != null && !executor.isShutdown()) {        
    executor.shutdownNow();
  }      
}
executor = null;

Answer 1

来自方法shutDownNow（）的Oracle文档：

除了尽力尝试停止处理正在执行的任务之外，没有任何保证。例如，typicalimplementations将通过Thread.Interrupt取消，因此任何未能响应中断的任务都可能永远不会终止。

您可以看到这个答案，它可能会帮助您：ExecutorService没有关闭