问信号量tryAcquire()方法不会立即返回

EN

try {

if(semaphore.tryAcquire(this.request_handling_time, 
TimeUnit.MILLISECONDS)) {
updateResource(resource, request);
response = channel.createResponse(request, CoapResponseCode.Changed_204);   
                                        logger.info("content changed");                                 
try {

if(request.getMaxAgeTopic()>=0) {

((PubSubTopic) resource).setmaxAgeTopicValue(request.getMaxAgeTopic());
}
}catch(NullPointerException ex){

    if(((PubSubTopic) resource).getmaxAgeTopicValue() > 0){
        ((PubSubTopic) resource).updateTopicLifeTime();
    }
}                                   
resource.changed(); // send notifications to the subscribers

// send notifications to the pendingRequest Clients if present
if(((PubSubTopic) resource).getPendingSubscribe().size() > 0) {
    ((PubSubTopic) resource).notifyPendingRequest();
}           
try {
        Thread.sleep(10000);        


    }
    catch (@SuppressWarnings("unused") InterruptedException e){
     /*do nothing*/
  }

semaphore.release();
}else {
    logger.info("Too many requests on topic "+resource.getPath());                                  
 response = channel.createResponse(request, 
 CoapResponseCode.Too_Many_Requests_429);   

 response.setMaxAge(retry_time_after_too_many_requests);
                                    }
} catch (InterruptedException e) {
   // TODO Auto-generated catch block
e.printStackTrace();
}finally {
semaphore.release();
}