private ReentrantLock pauseLock = new ReentrantLock();
 private Condition unpaused = pauseLock.newCondition();
 @Override
 public void execute(Runnable command) {
 pauseLock.lock();
 try {
  while (getPoolSize()==getMaximumPoolSize() && getQueue().remainingCapacity()==0)
  unpaused.await();
  super.execute(command);//放到lock外面的话，在压力测试下会有漏网的！
 } catch (InterruptedException e) {
  log.warn(this, e);
 } finally {
  pauseLock.unlock();
 }
 }
 @Override
 protected void afterExecute(Runnable r, Throwable t) {
 super.afterExecute(r,t);
 try{
  pauseLock.lock();
  unpaused.signal();
 }finally{
  pauseLock.unlock();
 }
 }