同样的错误消息又回来了！

2017-09-29 18:50:22.497 ERROR 11099 --- [8080-Acceptor-0] org.apache.tomcat.util.net.NioEndpoint   : Socket accept failed

java.io.IOException: Too many open files
    at sun.nio.ch.ServerSocketChannelImpl.accept0(Native Method) ~[na:1.8.0_141]
    at sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:422) ~[na:1.8.0_141]
    at sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:250) ~[na:1.8.0_141]
    at org.apache.tomcat.util.net.NioEndpoint$Acceptor.run(NioEndpoint.java:453) ~[tomcat-embed-core-8.5.15.jar!/:8.5.15]
    at java.lang.Thread.run(Thread.java:748) [na:1.8.0_141]

2017-09-29 18:50:23.885  INFO 11099 --- [Thread-3] ationConfigEmbeddedWebApplicationContext : Closing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@5387f9e0: startup date [Wed Sep 27 03:14:35 UTC 2017]; root of context hierarchy
2017-09-29 18:50:23.890  INFO 11099 --- [Thread-3] o.s.c.support.DefaultLifecycleProcessor  : Stopping beans in phase 2147483647
2017-09-29 18:50:23.891  WARN 11099 --- [Thread-3] o.s.c.support.DefaultLifecycleProcessor  : Failed to stop bean 'documentationPluginsBootstrapper'

    ... 7 common frames omitted

2017-09-29 18:50:53.891  WARN 11099 --- [Thread-3] o.s.c.support.DefaultLifecycleProcessor  : Failed to shut down 1 bean with phase value 2147483647 within timeout of 30000: [documentationPluginsBootstrapper]
2017-09-29 18:50:53.891  INFO 11099 --- [Thread-3] o.s.j.e.a.AnnotationMBeanExporter        : Unregistering JMX-exposed beans on shutdown
2017-09-29 18:50:53.894  INFO 11099 --- [Thread-3] com.app.controller.SearchController  : Closing the ES REST client

我尝试使用上一篇文章中的解决方案。

ElasticsearchConfig:

@Configuration
public class ElasticsearchConfig {

@Value("${elasticsearch.host}")
private String host;

@Value("${elasticsearch.port}")
private int port;

@Bean
public RestClient restClient() {
    return RestClient.builder(new HttpHost(host, port))
    .setRequestConfigCallback(new RestClientBuilder.RequestConfigCallback() {
        @Override
        public RequestConfig.Builder customizeRequestConfig(RequestConfig.Builder requestConfigBuilder) {
            return requestConfigBuilder.setConnectTimeout(5000).setSocketTimeout(60000);
        }
    }).setMaxRetryTimeoutMillis(60000).build();
}

SearchController：

@RestController
@RequestMapping("/api/v1")
public class SearchController {

    @Autowired
    private RestClient restClient;

    @RequestMapping(value = "/search", method = RequestMethod.GET, produces="application/json" )
    public ResponseEntity<Object> getSearchQueryResults(@RequestParam(value = "criteria") String criteria) throws IOException {

        // Setup HTTP Headers
        HttpHeaders headers = new HttpHeaders();
        headers.add("Content-Type", "application/json");

        // Setup query and send and return ResponseEntity...

        Response response = this.restClient.performRequest(...);
    }

    @PreDestroy
    public void cleanup() {
        try {
            logger.info("Closing the ES REST client");
            this.restClient.close();
        } 
        catch (IOException ioe) {
            logger.error("Problem occurred when closing the ES REST client", ioe);
        }
    }
}

pom.xml：

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.4.RELEASE</version>
</parent>

<dependencies>
    <!-- Spring -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>

    <!-- Elasticsearch -->
    <dependency>
        <groupId>org.elasticsearch</groupId>
        <artifactId>elasticsearch</artifactId>
        <version>5.5.0</version>
    </dependency>

    <dependency>
        <groupId>org.elasticsearch.client</groupId>
        <artifactId>transport</artifactId>
        <version>5.5.0</version>
    </dependency>

    <!-- Apache Commons -->
    <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-lang3</artifactId>
        <version>3.6</version>
    </dependency>

    <!-- Log4j -->
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.17</version>
    </dependency>
</dependencies>

这让我认为RestClient首先从来没有明确关闭连接…

这令人惊讶，因为我的基于Elasticsearch Spring Boot的微服务在两个不同的AWS EC-2服务器上实现了负载平衡。

日志文件报告该异常发生了2000次，直到最后prePrestroy（）关闭了客户端。请参阅在堆栈跟踪末尾记录的@PreDestroy（）清除方法中的INFO。

我是否需要在SearchController中显式放置一个finally子句并显式关闭RestClient连接？

至关重要的是，此IOException不再发生，因为此搜索微服务依赖于许多不同的移动客户端（iOS和Android）。

需要它具有容错能力和可伸缩性……或者至少不中断。

唯一的原因是在日志文件的底部：

2017-09-29 18:50:53.894  INFO 11099 --- [Thread-3] com.app.controller.SearchController : Closing the ES REST client

是因为我这样做了：

kill -3 jvm_pid

我应该保留@PreDestory
cleanup（）方法，但更改SearchController.getSearchResults（）方法的内容以反映如下内容：

@RequestMapping(value = "/search", method = RequestMethod.GET, produces="application/json" )
public ResponseEntity<Object> getSearchQueryResults(@RequestParam(value = "criteria") String criteria) throws IOException {
    // Setup HTTP Headers
    HttpHeaders headers = new HttpHeaders();
    headers.add("Content-Type", "application/json");

    // Setup query and send and return ResponseEntity...
    Response response = null;

    try {
        // Submit Query and Obtain Response
        response = this.restClient.performRequest("POST", endPoint, Collections.singletonMap("pretty", "true"), entity);
    } 
    catch(IOException ioe) {
        logger.error("Exception when performing POST request " + ioe);
    }
    finally {
        this.restClient.close();
    }
    // return response as EsResponse();
}

这样，RestClient连接始终关闭…

如果有人可以帮助我，将不胜感激。