1. Scene

HTTP requests are processed asynchronously;

1) No need to return, such as sending SMS, push messages, e-mail and other ancillary services, asynchronous processing, reduce the total time consumption of HTTP requests, improve customer experience.

2) If you need to return, the front-end will wait for the business processing result data, and the asynchronous processing will return to the main thread of HTTP request, and return to the front-end; if it is a single business that can be optimized here, please check the previous and next articles in this blog; if it is multiple business processing, you can use multiple asynchronous processing with return, and the total weight will summarize the result and return.

2. Knowledge points

1) Thread pool threadpooltaskexecutor

2) Note: @ enableasync, @ async (“asyncserviceexecutor”)

3) Return value encapsulates future & lt; T & gt;, new asyncresult & lt; & gt; (T)

3. Code examples

1）controller

package com.liuxd.controller;

import com.liuxd.entity.Responses;
import com.liuxd.service.TaskService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import java.util.concurrent.Future;

@Slf4j
@RestController
public class AsyncCtr {

    @Autowired
    private TaskService taskService;

    @RequestMapping(value = "/get", method = RequestMethod.GET)
    public Responses<String> getResult() throws Exception {

        log.info("HTTP request received...") ;
        long startTime = System.currentTimeMillis();

        //1. Asynchronous execution_processing_data_without_waiting
        taskService.handleData();

        //2. Asynchronous execution_processing_data_waiting_for_processing_results
        Future<String> future = taskService.getData();
        String result = future.get();

        log.info("Receiving HTTP request thread task completed, exit!") ;
        long endTime = System.currentTimeMillis();
        log.info("Total time spent on http request. " + (endTime - startTime) + "ms");

        return new Responses<>(0, result, "SUCCESS");

    }

}

2）service

package com.liuxd.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.Future;

@Slf4j
@Service
public class TaskService {

    @Async("asyncServiceExecutor")
    public void handleData() {

        log.info("Call service no return asynchronous method, start execution...");
        long startTime = System.currentTimeMillis();
        try {
            Thread.sleep(2500L);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        log.info("Call service no return asynchronous method, the end of execution!!!") ;
        long endTime = System.currentTimeMillis();
        log.info("Total time taken to call service without return asynchronous method. " + (endTime - startTime) + "ms");

    }

    @Async("asyncServiceExecutor")
    public Future<String> getData(){

        log.info("Call service has return asynchronous method, start execution...");
        long startTime = System.currentTimeMillis();

        try {
            Thread.sleep(2500L);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        log.info("Call service has returned asynchronous methods, the end of execution!!!") ;

        long endTime = System.currentTimeMillis();
        log.info("Total time to call service with return asynchronous method: " + (endTime - startTime) + "ms");

        return new AsyncResult<>("Asynchronous processing completed!");

    }


}

3) Thread pool

package com.liuxd.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;

import java.util.concurrent.Executor;
import java.util.concurrent.ThreadPoolExecutor;

/**
 * @program: unif-insure-service
 * @description: Thread Pool
 **/
@Configuration
@EnableAsync
public class ExecutorConfig {
    @Bean
    public Executor asyncServiceExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        //Configure the number of core threads
        executor.setCorePoolSize(5);
        // Configure the maximum number of threads
        executor.setMaxPoolSize(5);
        //configure queue size
        executor.setQueueCapacity(1000);
        //configure the name prefix of the threads in the thread pool
        executor.setThreadNamePrefix("async-system-");

        // rejection-policy: How to handle new tasks when the pool has reached its max size
        // CALLER_RUNS: instead of executing the task in the new thread, the caller's thread will execute it
        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
        //Execution initialization
        executor.initialize();
        return executor;
    }
}

4）Responses

package com.liuxd.entity;

import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
public class Responses<T> {

    private Integer code;

    private String msg;

    private T data;

}

5) Print results

6) Result analysis

1) There are three threads, HTTP request main thread, asynchronous no return thread, asynchronous return thread

2) The main thread does not need to wait for no return thread, it will wait for the result of return thread, and finally return