微服務架構中的依賴通過遠端呼叫實現，而遠端呼叫中最常見的問題就是通訊消耗與連線數佔用。在高併發的情況下，因通訊次數的增加，總的通訊時間消耗將會變得不那麼理想。同時，因為依賴服務的執行緒池資源有限，將出現排隊等待與相應延遲的情況，為了優化這個兩個問題，Hystrix提供啦HystrixCollapser來實現請求的合併，以減少通訊消耗和執行緒數的佔用。

 HystrixCollapser實現了在HystrixCommand之前放置一個合併處理器，將處於一個很短的時間窗(預設10毫秒)內對同一依賴服務

多個請求合併處理。

修改eureka-consume中pom檔案，新增依賴

<dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.29</version>
        </dependency>
 

package com.study.cloud.consumer.services;

import java.io.Serializable;

public class User implements Serializable {
    private static final long serialVersionUID = 1L;
    private long id;
    private String name;
    private String address;

    public User(){

    }
    public User(String name, String address,long id) {
        this.name = name;
        this.id = id;
        this.address = address;
    }

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }
}
 

package com.study.cloud.consumer.controllers;

import com.study.cloud.consumer.services.User;
import com.study.cloud.consumer.services.UserService;
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.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class UserController {


    @Autowired
    private UserService userService;


    @RequestMapping(value = "/user", method = RequestMethod.GET)
    public User finduser(@RequestParam(name = "id") Long id){
        System.out.println("id:"+id);
        return userService.find(id);
    }
}
 

package com.study.cloud.consumer.controllers;

import com.study.cloud.consumer.services.User;
import com.study.cloud.consumer.services.UserService;
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.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class UserController {


    @Autowired
    private UserService userService;


    @RequestMapping(value = "/user", method = RequestMethod.GET)
    public User finduser(@RequestParam(name = "id") Long id){
        System.out.println("id:"+id);
        return userService.find(id);
    }
}

package com.study.cloud.client.controllers;

import java.io.Serializable;

public class User implements Serializable {
    private static final long serialVersionUID = 1L;
    private long id;
    private String name;
    private String address;

    public User(){

    }
    public User(String name, String address,long id) {
        this.name = name;
        this.id = id;
        this.address = address;
    }

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }
}

package com.study.cloud.client.controllers;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

@RestController
public class HelloController {

    private List<User> users = new ArrayList<>();

    {
        users.add(new User("caohui1", "caohui1", 1L));
        users.add(new User("caohui2", "caohui2", 2L));
        users.add(new User("caohui3", "caohui3", 3L));
        users.add(new User("caohui4", "caohui4", 4L));
        users.add(new User("caohui5", "caohui5", 5L));
        users.add(new User("caohui6", "caohui6", 6L));
    }

    @Autowired
    private DiscoveryClient client;

    @RequestMapping(value = "/hello", method = RequestMethod.GET)
    public String sayHi(@RequestParam(value = "name") String name) {
        String host = client.getLocalServiceInstance().getHost();
        String serviceId = client.getLocalServiceInstance().getServiceId();
        int port = client.getLocalServiceInstance().getPort();
        return serviceId + ",host:" + host + ",port:" + port + " say hello " + name;
    }


    @RequestMapping(value = "/user", method = RequestMethod.GET)
    public List<User> users(@RequestParam(value = "ids") String ids) {
        System.out.println("ids:" + ids);
        List<User> collect = users.parallelStream().filter((item) -> ids.contains(String.valueOf(item.getId()))).collect(Collectors.toList());
        System.out.println("collect:" + collect);
        return collect;
    }

}

呼叫 http://localhost:9002/user?id=1，出現如下則表示成功