Spring-비동기처리

비동기 처리란?
특정 코드의 연산이 끝날 때까지 코드의 실행을 멈추지 않고
순차적으로 다음 코드를 먼저 실행

@async
1. public 메소드에만 작동한다. (private 메소드는 비동기로 작동하지 않는다)
2. 셀프 호출(같은 클래스 안에서 Async메소드를 호출하면 작동하지 않음)

package com.example.async;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableAsync;

@SpringBootApplication
@EnableAsync
public class AsyncApplication {

    public static void main(String[] args) {
        SpringApplication.run(AsyncApplication.class, args);
    }

}

package com.example.async.controller;


import com.example.async.service.AsyncService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.concurrent.CompletableFuture;

@Slf4j
@RestController
@RequestMapping("/api")
public class ApiController {

    private final AsyncService asyncService;

    public ApiController(AsyncService asyncService) {
        this.asyncService = asyncService;
    }

    @GetMapping("/hello")
    public CompletableFuture hello(){ //CompletableFuture 다른 스레드에서 실행을 시키고 결과를 반환받는 형태
        log.info("Completable Future init");
        return asyncService.run();

    }
}

package com.example.async.service;

import lombok.extern.slf4j.Slf4j;
import org.springframework.scheduling.annotation.Async;
import org.springframework.scheduling.annotation.AsyncResult;
import org.springframework.stereotype.Service;
import java.util.concurrent.CompletableFuture;


@Slf4j
@Service
public class AsyncService {

    @Async("async-thread")
    public CompletableFuture run() {
        return new AsyncResult(hello()).completable();

    }
    public String hello() {

        for (int i = 0; i < 10; i++) {
            try {
                Thread.sleep(2000);
                log.info("thread sleep....");
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        return "async hello";
    }
}

package com.example.async.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
import java.util.concurrent.Executor;

@Configuration

public class AppConfig {
    @Bean("async-thread")
    public Executor asyncThread(){
        ThreadPoolTaskExecutor ThreadPoolTaskExecutor = new ThreadPoolTaskExecutor();
        ThreadPoolTaskExecutor.setMaxPoolSize(100);
        ThreadPoolTaskExecutor.setCorePoolSize(10); //1.여기 10개가 차면 3.10개만 큼 늘어남
        ThreadPoolTaskExecutor.setQueueCapacity(10); //2.큐에 10개가 들어가고 4.20개 다 차면 또 여기로 옴
        ThreadPoolTaskExecutor.setThreadNamePrefix("Async-");
        return ThreadPoolTaskExecutor;
    }
}