如何在使用彈性搜索5.5.0獲得最佳性能時正確關閉原始RestClient？

Question

正在使用Spring Boot 1.5.4.RELEASE Microservice使用ElasticSearch提供的低級Rest Client連接到ElasticSearch 5.5.0實例。

的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> 

    <!-- Jackson --> 
    <dependency> 
     <groupId>com.fasterxml.jackson.core</groupId> 
     <artifactId>jackson-core</artifactId> 
     <version>2.8.9</version> 
    </dependency> 

    <dependency> 
     <groupId>com.fasterxml.jackson.core</groupId> 
     <artifactId>jackson-databind</artifactId> 
     <version>2.8.9</version> 
    </dependency> 

    <dependency> 
     <groupId>com.fasterxml.jackson.core</groupId> 
     <artifactId>jackson-annotations</artifactId> 
     <version>2.8.9</version> 
    </dependency> 

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

    <!-- JUnit --> 
    <dependency> 
     <groupId>junit</groupId> 
     <artifactId>junit</artifactId> 
     <version>4.11</version> 
     <scope>test</scope> 
    </dependency> 

    <!-- Swagger --> 
    <dependency> 
     <groupId>io.springfox</groupId> 
     <artifactId>springfox-swagger2</artifactId> 
     <version>2.6.1</version> 
     <scope>compile</scope> 
    </dependency> 

    <dependency> 
     <groupId>io.springfox</groupId> 
     <artifactId>springfox-swagger-ui</artifactId> 
     <version>2.6.1</version> 
     <scope>compile</scope> 
    </dependency> 
</dependencies> 

一切都設置正確，但一幫命中後，客戶端應用程序報告了一個HTTP 500錯誤，這是什麼出現在日誌文件：

java.io.IOException: Too many open files 
     at sun.nio.ch.IOUtil.makePipe(Native Method) ~[na:1.8.0_141] 
     at sun.nio.ch.EPollSelectorImpl.<init>(EPollSelectorImpl.java:65) ~[na:1.8.0_141] 
     at sun.nio.ch.EPollSelectorProvider.openSelector(EPollSelectorProvider.java:36) ~[na:1.8.0_141] 
     at java.nio.channels.Selector.open(Selector.java:227) ~[na:1.8.0_141] 
     at org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor.<init>(AbstractMultiworkerIOReactor.java:142) ~[httpcore-nio-4.4.5.jar!/:4.4.5] 
     at org.apache.http.impl.nio.reactor.DefaultConnectingIOReactor.<init>(DefaultConnectingIOReactor.java:79) ~[httpcore-nio-4.4.5.jar!/:4.4.5] 
     at org.apache.http.impl.nio.client.IOReactorUtils.create(IOReactorUtils.java:43) ~[httpasyncclient-4.1.3.jar!/:4.1.3] 
     at org.apache.http.impl.nio.client.HttpAsyncClientBuilder.build(HttpAsyncClientBuilder.java:666) ~[httpasyncclient-4.1.3.jar!/:4.1.3] 
     at org.elasticsearch.client.RestClientBuilder.createHttpClient(RestClientBuilder.java:202) ~[rest-5.5.0.jar!/:5.5.0] 
     at org.elasticsearch.client.RestClientBuilder.build(RestClientBuilder.java:180) ~[rest-5.5.0.jar!/:5.5.0] 
     at com.myapp.controller.SearchController.getSearchQueryResults(SearchController.java:94) ~[classes!/:1.0] 

Inside SearchController（//註釋後面的第二行是94行）：

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

    @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 RestClient 
     RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)) 
     .setRequestConfigCallback(new RestClientBuilder.RequestConfigCallback() { 
      @Override 
      public RequestConfig.Builder customizeRequestConfig(RequestConfig.Builder requestConfigBuilder) { 
       return requestConfigBuilder.setConnectTimeout(5000).setSocketTimeout(60000); 
      } 
     }).setMaxRetryTimeoutMillis(60000).build(); 

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

    } 
} 

它的顯然，它從未被調用restClient.performRequest（）方法關閉後...

所以，我要把它放到我的代碼：

Response response = null; 
try { 
    // Submit Query and Obtain Response 
    response = restClient.performRequest("POST", endPoint, Collections.singletonMap("pretty", "true"), entity); 
} 
catch (IOException e) { 
    LOG.error("\n\n\tException: " + e + "\n\n"); 
    e.printStackTrace(); 
} 
finally { 
    restClient.close(); 
} 

閱讀來自彈性搜索的文檔，該RESTClient實現類是線程-safe ...

另外，請閱讀有關restClient.performRequestAsync（）方法的內容，但對線程有點不熟悉，並且文檔中的說明含糊不清。

問題（S）：

1. 是我的解決方案來處理，並關閉了一堆插座資源的最佳方式？

2. 如果有人能夠向我展示一種更好的方式來使用帶Elastic Search的低級別RestClient，意味着它不會導致同樣的問題，導致HTTP 500不會釋放套接字資源。我應該使用restClient.performRequestAsync？有人可以提供一個例子嗎？

感謝您在百忙之中閱讀本文時...

Answer 1

這是不是一個很好的做法，對每一個請求創建一個RestClient。

@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(); 
    } 
} 

，然後在SearchController類，你可以注入像這樣（並且還添加了清理方法，當你的容器去關閉restClient比如：你應該通過配置Bean類似下面創建一個實例下）：

@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); 
     } 
    } 

}