高并发项目应用场景多线程性能优化

串行模式（123顺序执行，效率低下）

controller

@Controller
public class UserController {
	private UserService userService;
	@RequestMapping("/info")
	public Object getInfo(@RequestParam("userId")long userId) {
		return userService.getUserInfo(userId);
	}
}

service

@Service
public class UserService {
	@Autowired
	private RemoteService remoteService;
	public Object getUserInfo(long userId) {
		long currentTimeMillis = System.currentTimeMillis();
		
		String V1 = remoteService.get001Info(userId);
		JSONObject parseObject1 = JSONObject.parseObject(V1);
		
		String V2 = remoteService.get002Info(userId);
		JSONObject parseObject2 = JSONObject.parseObject(V2);
		
		JSONObject jsonObject = new JSONObject();
		jsonObject.putAll(parseObject1);
		jsonObject.putAll(parseObject2);
		
		System.out.println("串行time"+(System.currentTimeMillis()-currentTimeMillis));
		return jsonObject;
	}
}

service并行模式（稍微提升，非最优解）

不采用Runnable，它的Run方法没有返回值
采用Callable，它的call方法有返回值
通过.get方法获取返回值时如果线程没有走完，就会阻塞，阻塞的线程是web服务器的tomcat线程，大量线程阻塞，会导致网站吞吐量下降。

@Service
public class UserService {
	@Autowired
	private RemoteService remoteService;
	public Object getUserInfoConcurrent( final long userId) {
		/// 
//		Thread thread = new Thread(new Runnable() {
//			public void run() {
//				
//			}
//		}).start();
		
		long currentTimeMillis = System.currentTimeMillis();
		/业务1
		Callable userCall=new Callable() {
			public JSONObject call() throws Exception {
				String V1 = remoteService.get001Info(userId);
				JSONObject parseObject1 = JSONObject.parseObject(V1);
				return parseObject1;
			}
		};
		FutureTask userFuture = new FutureTask(userCall);
		new Thread(userFuture).start();
		/业务2
		Callable moneyCall=new Callable() {
			public JSONObject call() throws Exception {
				String V2 = remoteService.get002Info(userId);
				JSONObject parseObject2 = JSONObject.parseObject(V2);
				return parseObject2;
			}
		};
		FutureTask moneyFuture = new FutureTask(moneyCall);
		new Thread(moneyFuture).start();
		///------------------------------------------
		JSONObject jsonObject = new JSONObject();;
		try {
			jsonObject.putAll(userFuture.get());//获取返回值时如果线程没有走完，就会阻塞，阻塞的线程是web服务器的tomcat线程，大量线程阻塞，会导致网站吞吐量下降。
			jsonObject.putAll(moneyFuture.get());
		} catch (Exception e) {
			e.printStackTrace();
		}
		System.out.println("串行time"+(System.currentTimeMillis()-currentTimeMillis));
		return jsonObject;
	}
}

servlet3.0异步请求解决Tomcat线程阻塞

在controller层启动子线程（通过异步方式）
request过来，tomcat会启动一个子线程，然后自身结束，使得tomcat主线程的开闭许仙接近于0。
controller

@Controller
public class UserController {
	private UserService userService;
	@RequestMapping("/infoAsync")
	public Callable