通過Apache HTTP Nio與Elasticsearch REST Java客戶端進行OutOfMemoryError

Question

我們正在使用Elasticsearch REST Java客戶端（我們在Java 7上，因此不能使用普通的Elasticsearch Java客戶端）與我們的Elasticsearch服務器進行交互。 除了我們嘗試對約130萬個文檔進行初始索引編制外，所有其他方法都可以正常工作。 這運行了一段時間，但經過幾十萬份文檔，我們得到了

20/06 21:27:33,153 ERROR [cid=51][stderr][write:71] (pool-837116-thread-1) Exception in thread "pool-837116-thread-1" java.lang.OutOfMemoryError: unable to create new native thread
20/06 21:27:33,154 ERROR [cid=51][stderr][write:71] (pool-837116-thread-1)  at java.lang.Thread.start0(Native Method)
20/06 21:27:33,154 ERROR [cid=51][stderr][write:71] (pool-837116-thread-1)  at java.lang.Thread.start(Thread.java:693)
20/06 21:27:33,154 ERROR [cid=51][stderr][write:71] (pool-837116-thread-1)  at org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor.execute(AbstractMultiworkerIOReactor.java:334)
20/06 21:27:33,154 ERROR [cid=51][stderr][write:71] (pool-837116-thread-1)  at org.apache.http.impl.nio.conn.PoolingNHttpClientConnectionManager.execute(PoolingNHttpClientConnectionManager.java:194)
20/06 21:27:33,154 ERROR [cid=51][stderr][write:71] (pool-837116-thread-1)  at org.apache.http.impl.nio.client.CloseableHttpAsyncClientBase$1.run(CloseableHttpAsyncClientBase.java:64)
20/06 21:27:33,155 ERROR [cid=51][stderr][write:71] (pool-837116-thread-1)  at java.lang.Thread.run(Thread.java:724)

其次是

java.lang.IllegalStateException: Request cannot be executed; I/O reactor status: STOPPED
    at org.apache.http.util.Asserts.check(Asserts.java:46)
    at org.apache.http.impl.nio.client.CloseableHttpAsyncClientBase.ensureRunning(CloseableHttpAsyncClientBase.java:90)
    at org.apache.http.impl.nio.client.InternalHttpAsyncClient.execute(InternalHttpAsyncClient.java:123)
    at org.elasticsearch.client.RestClient.performRequestAsync(RestClient.java:343)
    at org.elasticsearch.client.RestClient.performRequestAsync(RestClient.java:325)
    at org.elasticsearch.client.RestClient.performRequest(RestClient.java:218)
    at org.elasticsearch.client.RestClient.performRequest(RestClient.java:191)

如您所見，Elasticsearch REST客戶端正在使用apache http nio。 我發現奇怪的是，Nio庫正在為每個單個請求（或連接？）創建一個線程。 從上面的日志中，您可以看到線程（pool-837116-thread-1）。 還有許多I / O調度程序線程，其數量在不斷增加。

但是，活動線程的總數似乎並沒有太大變化。 因此，似乎不是重用線程，而是為每個連接周期創建了一個（或實際上兩個）新線程。 上載基本上是：

1.創建客戶

    restClient = RestClient.builder(new HttpHost(host.getHost(),host.getPort(),host.getProtocol())/*,new HttpHost(host.getHost(),host.getPort()+1,host.getProtocol())*/)
                            .setHttpClientConfigCallback(new RestClientBuilder.HttpClientConfigCallback() {
                                @Override
                                public HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpClientBuilder) {
                                    return httpClientBuilder
                                            .setDefaultCredentialsProvider(credsProvider)
                                                                                }
                            }).setMaxRetryTimeoutMillis(30000).build();

2.使用json正文發送請求並關閉客戶端

        try{
            HttpEntity entity = new NStringEntity(json,ContentType.APPLICATION_JSON);
            Response indexResponse = restClient.performRequest("PUT", endpoint, parameters,entity,header);
            log.debug("Response #0 #1", indexResponse,indexResponse.getStatusLine());
            log.debug("Entity #0",indexResponse.getEntity());

        }finally{
            if(restClient!=null){
                log.debug("Closing restClient #0", restClient);
                restClient.close();
            }
        }

這正常嗎？ apache nio為什么不重用線程？ Elasticsearch REST客戶端，apache nio或我的代碼是否有問題？ 我在restClient上調用close，不確定我還應該做什么。

我試圖在IO Reactor上將線程數設置為1：

restClient = RestClient.builder(new HttpHost(host.getHost(),host.getPort(),host.getProtocol())/*,new HttpHost(host.getHost(),host.getPort()+1,host.getProtocol())*/)
                            .setHttpClientConfigCallback(new RestClientBuilder.HttpClientConfigCallback() {
                                @Override
                                public HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpClientBuilder) {
                                    return httpClientBuilder
                                            .setDefaultCredentialsProvider(credsProvider)
                                            .setDefaultIOReactorConfig(IOReactorConfig.custom().setIoThreadCount(1).build()); //set to one thread
                                }
                            }).setMaxRetryTimeoutMillis(30000).build();

但這並沒有改變有關線程重用的任何內容。

Answer 1

我已經找到了OutOfMemoryError的原因。 盡管我正在嘗試-最終將關閉客戶端的程序段-在該程序段外引發了異常（該程序段無法覆蓋D'oh的所有內容）。 但是創建這么多線程仍然是錯誤的（盡管總線程數並未顯着增加）。