为什么程序中突然多了 200 个 Dubbo-thread 线程的说明

"Dubbo-thread-200" #160932 daemon prio=5 os_prio=0 tid=0x00007f5af9b54800 nid=0x79a6 waiting on condition [0x00007f5a9acd5000]
  java.lang.Thread.State: WAITING (parking)
 at sun.misc.Unsafe.park(Native Method)
 - parking to wait for <0x00000000c78f1240> (a java.util.concurrent.SynchronousQueue$TransferStack)
 at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
 at java.util.concurrent.SynchronousQueue$TransferStack.awaitFulfill(SynchronousQueue.java:458)
 at java.util.concurrent.SynchronousQueue$TransferStack.transfer(SynchronousQueue.java:362)
 at java.util.concurrent.SynchronousQueue.take(SynchronousQueue.java:924)
 at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
 at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
 at java.lang.Thread.run(Thread.java:748)

  Locked ownable synchronizers:
 - None

fixed=org.apache.dubbo.common.threadpool.support.fixed.FixedThreadPool
cached=org.apache.dubbo.common.threadpool.support.cached.CachedThreadPool
limited=org.apache.dubbo.common.threadpool.support.limited.LimitedThreadPool
eager=org.apache.dubbo.common.threadpool.support.eager.EagerThreadPool

 /**
   * Get called when the server or client instance initiating.
   *
   * @param url
   * @return
   */
  public synchronized ExecutorService createExecutorIfAbsent(URL url) {
    String componentKey = EXECUTOR_SERVICE_COMPONENT_KEY;
    if (CONSUMER_SIDE.equalsIgnoreCase(url.getParameter(SIDE_KEY))) {
      componentKey = CONSUMER_SIDE;
    }
    Map<Integer, ExecutorService> executors = data.computeIfAbsent(componentKey, k -> new ConcurrentHashMap<>());
    Integer portKey = url.getPort();
    ExecutorService executor = executors.computeIfAbsent(portKey, k -> createExecutor(url));
    // If executor has been shut down, create a new one
    if (executor.isShutdown() || executor.isTerminated()) {
      executors.remove(portKey);
      executor = createExecutor(url);
      executors.put(portKey, executor);
    }
    return executor;
  }

  public ExecutorService getExecutor(URL url) {
    String componentKey = EXECUTOR_SERVICE_COMPONENT_KEY;
    if (CONSUMER_SIDE.equalsIgnoreCase(url.getParameter(SIDE_KEY))) {
      componentKey = CONSUMER_SIDE;
    }
    Map<Integer, ExecutorService> executors = data.get(componentKey);

    /**
     * It's guaranteed that this method is called after {@link #createExecutorIfAbsent(URL)}, so data should already
     * have Executor instances generated and stored.
     */
    if (executors == null) {
      logger.warn("No available executors, this is not expected, framework should call createExecutorIfAbsent first " +
          "before coming to here.");
      return null;
    }

    Integer portKey = url.getPort();
    ExecutorService executor = executors.get(portKey);
    if (executor != null) {
      if (executor.isShutdown() || executor.isTerminated()) {
        executors.remove(portKey);
        executor = createExecutor(url);
        executors.put(portKey, executor);
      }
    }
    return executor;
  }

private void initExecutor(URL url) {
    url = ExecutorUtil.setThreadName(url, CLIENT_THREAD_POOL_NAME);
    url = url.addParameterIfAbsent(THREADPOOL_KEY, DEFAULT_CLIENT_THREADPOOL);
    executor = executorRepository.createExecutorIfAbsent(url);
  }