restTemplate踩过的坑-spring clound--cloud内部服务调用重试次数

转载自 https://www.cnblogs.com/jimw/p/9037542.html

现在公司项目基本都从臃肿的项目转换成微服务的方向转换，因此也从中使用了spring clound的一些组件，在此过程中就遇到了restTemplate的坑。

起初，是直接注入RestTemplate，后来则不断的遇到错误日志无法请求，出现异常。

异常信息：

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.IllegalStateException: No instances available for IP

意思是说url必须是服务的名称，猜测应该是涉及到eureka，直接用ip跟url调用是直接报错的。

因此不适用默认的，直接重新自定义，则引用了原有的注入修改一下。

/**
 *
 * 功能描述：
 *
 * @作者 jimw 创建时间：2018-04
 *
 */
@Configuration
public class RestTemplateConfig {
    public RestTemplate restTemplate() {
        return new RestTemplate(getClientHttpRequestFactory());
    }
    /**
     * 配置HttpClient超时时间
     *
     * @return
     */
    private ClientHttpRequestFactory getClientHttpRequestFactory() {
        RequestConfig requestConfig = RequestConfig.custom().setSocketTimeout(HTTP_SOCKET_TIMEOUT)
                .setConnectTimeout(HTTP_CONNECT_TIMEOUT).build();
        CloseableHttpClient client = HttpClientBuilder.create().setDefaultRequestConfig(requestConfig).build();
        return new HttpComponentsClientHttpRequestFactory(client);
    }
    /** http请求socket连接超时时间,毫秒为单位 */
    public static final int HTTP_SOCKET_TIMEOUT = 15000;
    /** http请求连接超时时间,毫秒为单位 */
    public static final int HTTP_CONNECT_TIMEOUT = 15000;
}

　　

当配置了这个之后，服务正常了。观察了一段时间，发现在并发的高峰期，开多几个服务器负载，也会存在服务出现请求非常慢，导致接口出现阻塞的情况出现，经过分析

1、出现阻塞的原因是因为高峰并发的时候，出现请求的链接数很大

因此找了源码，发现是因为restTemplate的默认配置值小于请求的链接数，而且路由并发也是默认为5的,因为微服务之间的逻辑处理中也有一定的时间。出现大规模阻塞的坑就这么踩到了。 

对代码改造一下，配置最大链接数，路由并发数，这个restTemplate的坑就这么解决了。

package com.jingbei.guess.config.web;
import java.security.KeyManagementException;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.SSLContext;
import org.apache.http.client.HttpClient;
import org.apache.http.config.Registry;
import org.apache.http.config.RegistryBuilder;
import org.apache.http.conn.socket.ConnectionSocketFactory;
import org.apache.http.conn.socket.PlainConnectionSocketFactory;
import org.apache.http.conn.ssl.NoopHostnameVerifier;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.conn.ssl.SSLContextBuilder;
import org.apache.http.conn.ssl.TrustStrategy;
import org.apache.http.impl.client.DefaultHttpRequestRetryHandler;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
import org.springframework.web.client.DefaultResponseErrorHandler;
import org.springframework.web.client.RestTemplate;
import lombok.extern.slf4j.Slf4j;
/**
 *
 * 功能描述：
 *
 * @作者 jimw 创建时间： 2018-04
 *
 */
@Slf4j
@Configuration
public class RestTemplateConfig {
    @Bean
    public RestTemplate restTemplate() {
        RestTemplate restTemplate = new RestTemplate();
        restTemplate.setRequestFactory(clientHttpRequestFactory());
        restTemplate.setErrorHandler(new DefaultResponseErrorHandler());
        return restTemplate;
    }
    @Bean
    public HttpComponentsClientHttpRequestFactory clientHttpRequestFactory() {
        try {
            HttpClientBuilder httpClientBuilder = HttpClientBuilder.create();
            SSLContext sslContext = new SSLContextBuilder().loadTrustMaterial(null, new TrustStrategy() {
                public boolean isTrusted(X509Certificate[] arg0, String arg1) throws CertificateException {
                    return true;
                }
            }).build();
            httpClientBuilder.setSSLContext(sslContext);
            HostnameVerifier hostnameVerifier = NoopHostnameVerifier.INSTANCE;
            SSLConnectionSocketFactory sslConnectionSocketFactory = new SSLConnectionSocketFactory(sslContext,
                    hostnameVerifier);
            Registry<ConnectionSocketFactory> socketFactoryRegistry = RegistryBuilder.<ConnectionSocketFactory>create()
                    .register("http", PlainConnectionSocketFactory.getSocketFactory())
                    .register("https", sslConnectionSocketFactory).build();// 注册http和https请求
            // 开始设置连接池
            PoolingHttpClientConnectionManager poolingHttpClientConnectionManager = new PoolingHttpClientConnectionManager(
                    socketFactoryRegistry);
            poolingHttpClientConnectionManager.setMaxTotal(2700); // 最大连接数2700
            poolingHttpClientConnectionManager.setDefaultMaxPerRoute(100); // 同路由并发数100
            httpClientBuilder.setConnectionManager(poolingHttpClientConnectionManager);
            httpClientBuilder.setRetryHandler(new DefaultHttpRequestRetryHandler(3, true)); // 重试次数
            HttpClient httpClient = httpClientBuilder.build();
            HttpComponentsClientHttpRequestFactory clientHttpRequestFactory = new HttpComponentsClientHttpRequestFactory(
                    httpClient); // httpClient连接配置
            clientHttpRequestFactory.setConnectTimeout(20000); // 连接超时
            clientHttpRequestFactory.setReadTimeout(30000); // 数据读取超时时间
            clientHttpRequestFactory.setConnectionRequestTimeout(20000); // 连接不够用的等待时间
            return clientHttpRequestFactory;
        } catch (KeyManagementException | NoSuchAlgorithmException | KeyStoreException e) {
            log.error("初始化HTTP连接池出错", e);
        }
        return null;
    }
}

　　在对应的插件中配置即可

依赖包：

<dependency>

<groupId>org.apache.httpcomponents</groupId>

<artifactId>httpclient</artifactId>

<version>4.5.3</version>

</dependency>

<dependency>

<groupId>org.apache.httpcomponents</groupId>

<artifactId>httpcore</artifactId>

<version>4.4.9</version>

</dependency>