Java 21/Spring Boot 3.1.6多API调用应用间歇性连接超时求助

我们的应用基于Java 21和Spring Boot 3.1.6开发，作为Amadeus API的包装器，需调用35+个外部接口，目前出现间歇性连接超时情况。针对Amadeus API开展的负载测试均能正常返回结果，但其他使用Java 21、调用不同服务的同类应用也存在相同问题。

以下是相关代码及报错信息，恳请协助排查根本原因：

RestTemplate 配置代码 #

@Bean(name = "restTemplate")
@Scope(scopeName = "request", proxyMode = ScopedProxyMode.TARGET_CLASS)
public RestTemplate restTemplate(RestTemplateBuilder builder) {
    return configureRestTemplate(builder);
}

private RestTemplate configureRestTemplate(RestTemplateBuilder builder) {
    RestTemplate restTemplate = new RestTemplate(new BufferingClientHttpRequestFactory(new SimpleClientHttpRequestFactory()));
    List<ClientHttpRequestInterceptor> interceptors = new ArrayList<>();
    interceptors.add(new LoggingRequestInterceptor());
    restTemplate.setInterceptors(interceptors);
    if (CollectionUtils.isEmpty(interceptors)) {
        interceptors = new ArrayList<>();
    }
    HttpComponentsClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory();
    restTemplate.setRequestFactory(requestFactory);
    return restTemplate;
}

API 调用代码 #

@Autowired
private RestTemplate restTemplate;

private <T, U> U exchangeData(URI uri, T data, Class<U> clazz, HttpHeaders requestHeaders, HttpMethod method,
                              boolean... errorCustomization) {
    HttpEntity<T> requestEntity = new HttpEntity<>(data, requestHeaders);
    ResponseEntity<U> response = null;
    try {
        response = restTemplate.exchange(uri, method, requestEntity, clazz);

    } catch (RestClientException e) {
        List<ErrorModel> errorDetails = new ArrayList<>();
        errorDetails.add(new ErrorModel(e.getClass().getName(), e.getMessage()));
        LOG.error("Error while calling external service", e);
        throw applicationErrorConfig.createExternalException(ApiExternalErrorType.SERVER_INTERNAL_ERROR,
                errorDetails);

    }
    restErrorManagerUtil.handleExternalServerErrorForComposite(data, response.getBody(), errorCustomization);
    return response.getBody();
}

报错堆栈信息 #

org.springframework.web.client.ResourceAccessException: I/O error on GET request for "https://xxxx**********************": Connect to https://xxxx********************** [domain/ip] failed: Operation timed out
    at org.springframework.web.client.RestTemplate.createResourceAccessException(RestTemplate.java:888)
    ...
Caused by: org.apache.hc.client5.http.HttpHostConnectException: Connect to https://xxxx********************** [domain/ip] failed: Operation timed out
    ...

排查方向建议 #

1. 补全连接池配置：当前HttpComponentsClientHttpRequestFactory未配置任何连接池参数，默认连接数有限且无超时控制，高并发下易出现连接耗尽导致超时。建议添加连接池及超时配置：

   HttpComponentsClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory();
   // 设置连接超时、读取超时
   requestFactory.setConnectTimeout(3000);
   requestFactory.setReadTimeout(5000);
   // 配置连接池
   PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager();
   connectionManager.setMaxTotal(200); // 最大总连接数
   connectionManager.setDefaultMaxPerRoute(50); // 单路由最大连接数
   requestFactory.setHttpClient(HttpClients.custom().setConnectionManager(connectionManager).build());
   

2. 排查Java 21网络特性兼容性：多个Java 21应用均出现该问题，需验证是否是Java 21网络默认参数变更导致。比如HTTP/2默认启用、TCP存活参数调整等，可强制使用HTTP/1.1测试：

   RequestConfig requestConfig = RequestConfig.custom()
           .setConnectTimeout(3000)
           .setConnectionRequestTimeout(3000)
           .setSocketTimeout(5000)
           .build();
   CloseableHttpClient httpClient = HttpClients.custom()
           .setDefaultRequestConfig(requestConfig)
           .setConnectionManager(connectionManager)
           .disableHttp2() // 禁用HTTP/2，强制使用HTTP/1.1
           .build();
   requestFactory.setHttpClient(httpClient);
   

3. 检查DNS解析问题：间歇性超时可能和DNS缓存过期、解析延迟有关，可尝试调整JVM DNS缓存参数（如networkaddress.cache.ttl和networkaddress.cache.negative.ttl），或直接用IP地址调用接口验证是否缓解。

4. 调整RestTemplate作用域：当前RestTemplate为request作用域，每次请求都会创建新实例，无法复用连接池，高并发下频繁创建销毁连接会引发超时。建议改为默认的singleton作用域，配合连接池复用连接资源。

内容的提问来源于stack exchange，提问作者jerald jacob