Java访问Elasticsearch报错Request cannot be executed； I/O reactor status: STOPPED

陈明亮chenml 2024-05-10 原文

简介

使用ES过程中遇到一个Request cannot be executed; I/O reactor status: STOPPED 的异常，大概意思是和server端的连接异常终止了。开始以为是引用的版本不对，或者自己使用问题，后来发现就是因为OOM导致程序宕机，进而引发连接终止。

环境

功能

SpringBoot 的程序通过 SpringDataElasticsearch 访问ES-server 获取数据。

ES-SERVER

版本：7.15.2

ES-CLIENT

ES-CLIENT 就是 SpringBoot 程序，核心pom依赖：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-elasticsearch</artifactId>
    <version>2.5.3</version>
</dependency>

问题

部署到测试环境之后，用户量大了之后接口报错，报错信息为：

Request cannot be executed; I/O reactor status: STOPPED

后端程序处于假死状态，访问其他接口一直转圈，无法响应内容
重启程序之后一切正常，用户量大了之后又有此问题
详细报错日志为：

2021-12-31/19:26:31.748||||^_^|[pool-4-thread-1] ERROR o.a.http.impl.nio.client.InternalHttpAsyncClient 66 - I/O reactor terminated abnormally
org.apache.http.nio.reactor.IOReactorException: I/O dispatch worker terminated abnormally
        at org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor.execute(AbstractMultiworkerIOReactor.java:359)
        at org.apache.http.impl.nio.conn.PoolingNHttpClientConnectionManager.execute(PoolingNHttpClientConnectionManager.java:221)
        at org.apache.http.impl.nio.client.CloseableHttpAsyncClientBase$1.run(CloseableHttpAsyncClientBase.java:64)
        at java.base/java.lang.Thread.run(Thread.java:829)
Caused by: java.lang.OutOfMemoryError: Java heap space
2021-12-31/19:26:32.783||||^_^|[http-nio-8092-exec-3] ERROR com.nghsmart.datacenter.handler.ExceptionHandler 67 - handleRuntimeException:
java.lang.RuntimeException: Request cannot be executed; I/O reactor status: STOPPED
        at org.elasticsearch.client.RestClient.extractAndWrapCause(RestClient.java:888)
        at org.elasticsearch.client.RestClient.performRequest(RestClient.java:283)
        at org.elasticsearch.client.RestClient.performRequest(RestClient.java:270)
        at org.elasticsearch.client.RestHighLevelClient.internalPerformRequest(RestHighLevelClient.java:1654)
        at org.elasticsearch.client.RestHighLevelClient.performRequest(RestHighLevelClient.java:1624)
        at org.elasticsearch.client.RestHighLevelClient.performRequestAndParseEntity(RestHighLevelClient.java:1594)
        at org.elasticsearch.client.RestHighLevelClient.search(RestHighLevelClient.java:1110)
        at org.springframework.data.elasticsearch.core.ElasticsearchRestTemplate.lambda$search$11(ElasticsearchRestTemplate.java:296)
        at org.springframework.data.elasticsearch.core.ElasticsearchRestTemplate.execute(ElasticsearchRestTemplate.java:383)
        at org.springframework.data.elasticsearch.core.ElasticsearchRestTemplate.search(ElasticsearchRestTemplate.java:296)
        at org.springframework.data.elasticsearch.core.AbstractElasticsearchTemplate.search(AbstractElasticsearchTemplate.java:513)
        at com.nghsmart.datacenter.domain.area.service.impl.AreaDashboradServiceImpl.getRotationStatisticsInfo(AreaDashboradServiceImpl.java:166)
        at com.nghsmart.datacenter.domain.area.controller.AreaDashboradController.getRotationStatisticsInfo(AreaDashboradController.java:76)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:197)
        at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:141)
        at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808)
        at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1064)
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963)
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
        at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:655)
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:764)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:228)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163)
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163)
        at com.nghsmart.commonauthentication.filter.JwtAuthenticationTokenFilter.doFilterInternal(JwtAuthenticationTokenFilter.java:52)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163)
        at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163)
        at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163)
        at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:96)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163)
        at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357)
        at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:382)
        at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
        at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:893)
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1723)
        at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.base/java.lang.Thread.run(Thread.java:829)
Caused by: 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.performRequest(RestClient.java:279)
... 69 common frames omitted

测试环境用户量一大就报，本地IDEA中一次也没有报这个问题
使用JMETER设置50个线程并发访问可以稳定复现此问题

原因

程序接口中将一块很大的数据存进JAVA集合中引发了oom，oom异常导致程序宕机，处于假死状态，进而导致 ES-CLIENT 和 ES-SERVER 端的 http 连接异常终止，然后org.apache.http.impl.nio.client.CloseableHttpAsyncClientBase.ensureRunning 方法报异常。

ensureRunning:

protected void ensureRunning() {
    final Status currentStatus = this.status.get();
    Asserts.check(currentStatus == Status.ACTIVE, "Request cannot be executed; " +
            "I/O reactor status: %s", currentStatus);
}

check:

public static void check(final boolean expression, final String message, final Object arg) {
    if (!expression) {
        throw new IllegalStateException(String.format(message, arg));
    }
}

SpringDataElasticsearch 和ES-SERVER 是长链接，只要报了OOM，当前和 ES-SERVER 的连接线程都将报异常，也就是说，虽然OOM只报了一次，但是可能有多个线程都在 Asserts.check 方法中报异常
其实不仅仅是和ES-SERVER 的连接异常关闭，观察大量日志后发现和nacos 的连接也有问题：

2022-01-04 15:59:07.366 [com.alibaba.nacos.client.remote.worker]  INFO com.alibaba.nacos.common.remote.client.printIfInfoEnabled:60 - [117be10e-119f-4253-a348-71c95a8978a1]Server healthy check fail,currentConnection=1641282430796_192.168.1.90_43108
2022-01-04 15:59:07.367 [com.alibaba.nacos.client.remote.worker]  INFO com.alibaba.nacos.common.remote.client.printIfInfoEnabled:60 - [117be10e-119f-4253-a348-71c95a8978a1] try to re connect to a new server ,server is  not appointed,will choose a random server.

测试环境运行SpringBoot内存配置为：-Xms256m -Xmx512m，使用 java -jar 命令启动。测试环境能复现，本地idea无法复现的原因是内存配置不同导致的，本地idea内存给的2g。编辑 run/debug configuration ，设置 VM options 和测试环境相同，使用jemter压测本地idea中跑的程序，也能复现此问题

解决办法

优化接口，解决OOM问题
增大测试环境内存配置

解决过程

HttpClient问题

这个思路并没有解决我的问题，但是解决问题的过程中花了大量时间研究。其实应该仔细阅读报错log的上下文和接口代码上下文，一开始没有留意到oom的异常

大概意思是说低版本 httpClient 有这个问题，高版本就没有这个问题，是apache-httpclient 导致的。具体是因为捕获到线程异常之后http连接就主动终止了，解决思路是升级版本或者是重写处理器，遇到异常之后不终止连接。

升级httpclient相关pom依赖：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-elasticsearch</artifactId>
    <!-- 排除 httpclient、httpcore、 httpcore-nio这三个依赖，并手动引入最新版本，解决es客户端报Request cannot be executed; I/O reactor status: STOPPED问题 -->
    <exclusions>
<!--                <exclusion>-->
<!--                    <groupId>org.apache.httpcomponents</groupId>-->
<!--                    <artifactId>httpclient</artifactId>-->
<!--                </exclusion>-->
<!--                <exclusion>-->
<!--                    <groupId>org.apache.httpcomponents</groupId>-->
<!--                    <artifactId>httpcore</artifactId>-->
<!--                </exclusion>-->
<!--                <exclusion>-->
<!--                    <groupId>org.apache.httpcomponents</groupId>-->
<!--                    <artifactId>httpcore-nio</artifactId>-->
<!--                </exclusion>-->
        <exclusion>
            <groupId>org.elasticsearch.client</groupId>
            <artifactId>elasticsearch-rest-client</artifactId>
        </exclusion>
    </exclusions>
</dependency>


<!-- start -->
<dependency>
    <groupId>org.elasticsearch.client</groupId>
    <artifactId>elasticsearch-rest-client</artifactId>
    <version>7.15.2</version>
    <exclusions>
        <exclusion>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
        </exclusion>
        <exclusion>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpcore</artifactId>
        </exclusion>
        <exclusion>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpcore-nio</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<!--  end  -->
<!-- start：排除 httpclient、httpcore、 httpcore-nio这三个依赖，并手动引入最新版本，解决es客户端报Request cannot be executed; I/O reactor status: STOPPED问题 -->
<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.13</version>
</dependency>

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpcore-nio</artifactId>
    <version>4.4.14</version>
</dependency>

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpcore</artifactId>
    <version>4.4.14</version>
</dependency>

<!--  end   -->

重写ElasticsearchRestTemplate：


import com.alibaba.fastjson.JSON;
import lombok.extern.slf4j.Slf4j;
import org.apache.http.Header;
import org.apache.http.HttpHost;
import org.apache.http.auth.AuthScope;
import org.apache.http.auth.UsernamePasswordCredentials;
import org.apache.http.client.CredentialsProvider;
import org.apache.http.impl.client.BasicCredentialsProvider;
import org.apache.http.impl.client.DefaultConnectionKeepAliveStrategy;
import org.apache.http.impl.nio.conn.PoolingNHttpClientConnectionManager;
import org.apache.http.impl.nio.reactor.DefaultConnectingIOReactor;
import org.apache.http.message.BasicHeader;
import org.apache.http.nio.reactor.IOReactorException;
import org.apache.http.nio.reactor.IOReactorExceptionHandler;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestClientBuilder;
import org.elasticsearch.client.RestHighLevelClient;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.elasticsearch.core.ElasticsearchRestTemplate;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
@Slf4j
@Configuration
public class EsClientConfig {
   
    @Value("${es.host}")
    private String host;
    @Value("${es.port}")
    private Integer port;
   
    @Bean
    public ElasticsearchRestTemplate initElasticsearchRestTemplate() {
        RestClientBuilder builder = RestClient.builder(new HttpHost(host, port))
                .setRequestConfigCallback(
                        config -> config.setConnectTimeout(180000)
                                .setConnectionRequestTimeout(180000)
                                .setSocketTimeout(180000))
                .setHttpClientConfigCallback(
                        httpClientBuilder -> {
                            httpClientBuilder.setMaxConnTotal(100);
                            httpClientBuilder.setMaxConnPerRoute(50);
                            List<Header> headers = new ArrayList<>(2);
                            headers.add(new BasicHeader("Connection", "keep-alive"));
                            headers.add(new BasicHeader("Keep-Alive", "720"));
                            httpClientBuilder.setDefaultHeaders(headers);
                            httpClientBuilder.setKeepAliveStrategy(DefaultConnectionKeepAliveStrategy.INSTANCE);
                            try {
                                DefaultConnectingIOReactor ioReactor = new DefaultConnectingIOReactor();
                                ioReactor.setExceptionHandler(new IOReactorExceptionHandler() {
                                    @Override
                                    public boolean handle(IOException e) {
                                        log.debug("System may be unstable: IOReactor encountered a checked exception : " + e.getMessage());
                                        log.debug("start setHttpClientConfigCallback handle IOException e printStackTrace");
                                        e.printStackTrace();
                                        log.debug("end setHttpClientConfigCallback handle IOException e printStackTrace");
                                        // Return true to note this exception as handled, it will not be re-thrown
                                        return true;
                                    }
                                    @Override
                                    public boolean handle(RuntimeException e) {
                                        log.debug("System may be unstable: IOReactor encountered a runtime exception : " + e.getMessage() + ",e is {}", e);
                                        log.debug("start setHttpClientConfigCallback handle RuntimeException e printStackTrace ");
                                        e.printStackTrace();
                                        log.debug("end setHttpClientConfigCallback handle RuntimeException e printStackTrace ");
                                        // Return true to note this exception as handled, it will not be re-thrown
                                        return true;
                                    }
                                });
                                httpClientBuilder.setConnectionManager(new PoolingNHttpClientConnectionManager(ioReactor));
                            } catch (IOReactorException e) {
                                throw new RuntimeException(e);
                            }
                            return httpClientBuilder;
                        }
                );
        ElasticsearchRestTemplate elasticsearchRestTemplate = new ElasticsearchRestTemplate(new RestHighLevelClient(builder));
        return elasticsearchRestTemplate;
    }
}

关于此问题相关参考：

https://www.cnblogs.com/yangchongxing/p/15440197.html
https://github.com/elastic/elasticsearch/issues/42133
https://zhuanlan.zhihu.com/p/384269417
https://cloud.tencent.com/developer/article/1806886

引用

https://www.cnblogs.com/Naylor/p/15763941.html

有关Java访问Elasticsearch报错Request cannot be executed； I/O reactor status: STOPPED的更多相关文章

ruby - 为什么我可以在 Ruby 中使用 Object#send 访问私有(private)/ protected 方法？ - 2
类classAprivatedeffooputs:fooendpublicdefbarputs:barendprivatedefzimputs:zimendprotecteddefdibputs:dibendendA的实例a=A.new测试a.foorescueputs:faila.barrescueputs:faila.zimrescueputs:faila.dibrescueputs:faila.gazrescueputs:fail测试输出failbarfailfailfail.发送测试[:foo,:bar,:zim,:dib,:gaz].each{|m|a.send(m)resc
ruby-on-rails - 在混合/模块中覆盖模型的属性访问器 - 2
我有一个包含模块的模型。我想在模块中覆盖模型的访问器方法。例如:classBlah这显然行不通。有什么想法可以实现吗？最佳答案您的代码看起来是正确的。我们正在毫无困难地使用这个确切的模式。如果我没记错的话，Rails使用#method_missing作为属性setter，因此您的模块将优先，阻止ActiveRecord的setter。如果您正在使用ActiveSupport::Concern(参见thisblogpost)，那么您的实例方法需要进入一个特殊的模块:classBlah
ruby - 续集在添加关联时访问many_to_many连接表 - 2
我正在使用Sequel构建一个愿望list系统。我有一个wishlists和itemstable和一个items_wishlists连接表(该名称是续集选择的名称)。items_wishlists表还有一个用于facebookid的额外列(因此我可以存储opengraph操作)，这是一个NOTNULL列。我还有Wishlist和Item具有续集many_to_many关联的模型已建立。Wishlist类也有:selectmany_to_many关联的选项设置为select:[:items.*,:items_wishlists__facebook_action_id].有没有一种方法可以
java - 等价于 Java 中的 Ruby Hash - 2
我真的很习惯使用Ruby编写以下代码:my_hash={}my_hash['test']=1Java中对应的数据结构是什么？最佳答案 HashMapmap=newHashMap();map.put("test",1);我假设？关于java-等价于Java中的RubyHash，我们在StackOverflow上找到一个类似的问题： https://stackoverflow.com/questions/22737685/
java - 从 JRuby 调用 Java 类的问题 - 2
我正在尝试使用boilerpipe来自JRuby。我看过guide从JRuby调用Java，并成功地将它与另一个Java包一起使用，但无法弄清楚为什么同样的东西不能用于boilerpipe。我正在尝试基本上从JRuby中执行与此Java等效的操作:URLurl=newURL("http://www.example.com/some-location/index.html");Stringtext=ArticleExtractor.INSTANCE.getText(url);在JRuby中试过这个:require'java'url=java.net.URL.new("http://www
java - 我的模型类或其他类中应该有逻辑吗 - 2
我只想对我一直在思考的这个问题有其他意见，例如我有classuser_controller和classuserclassUserattr_accessor:name,:usernameendclassUserController//dosomethingaboutanythingaboutusersend问题是我的User类中是否应该有逻辑user=User.newuser.do_something(user1)oritshouldbeuser_controller=UserController.newuser_controller.do_something(user1,user2)我
java - 什么相当于 ruby 的 rack 或 python 的 Java wsgi？ - 2
什么是ruby的rack或python的Java的wsgi？还有一个路由库。最佳答案来自Python标准PEP333:Bycontrast,althoughJavahasjustasmanywebapplicationframeworksavailable,Java's"servlet"APImakesitpossibleforapplicationswrittenwithanyJavawebapplicationframeworktoruninanywebserverthatsupportstheservletAPI.ht
Observability：从零开始创建 Java 微服务并监控它（二） - 2
这篇文章是继上一篇文章“Observability：从零开始创建Java微服务并监控它（一）”的续篇。在上一篇文章中，我们讲述了如何创建一个Javaweb应用，并使用Filebeat来收集应用所生成的日志。在今天的文章中，我来详述如何收集应用的指标，使用APM来监控应用并监督web服务的在线情况。源码可以在地址 https://github.com/liu-xiao-guo/java_observability 进行下载。摄入指标指标被视为可以随时更改的时间点值。当前请求的数量可以改变任何毫秒。你可能有1000个请求的峰值，然后一切都回到一个请求。这也意味着这些指标可能不准确，你还想提取最小/
【Java 面试合集】HashMap中为什么引入红黑树，而不是AVL树呢 - 2
HashMap中为什么引入红黑树，而不是AVL树呢1.概述开始学习这个知识点之前我们需要知道，在JDK1.8以及之前，针对HashMap有什么不同。JDK1.7的时候，HashMap的底层实现是数组+链表JDK1.8的时候，HashMap的底层实现是数组+链表+红黑树我们要思考一个问题，为什么要从链表转为红黑树呢。首先先让我们了解下链表有什么不好？？？2.链表上述的截图其实就是链表的结构，我们来看下链表的增删改查的时间复杂度增：因为链表不是线性结构，所以每次添加的时候，只需要移动一个节点，所以可以理解为复杂度是N(1)删：算法时间复杂度跟增保持一致查：既然是非线性结构，所以查询某一个节点的时候
深度学习部署：Windows安装pycocotools报错解决方法 - 2
深度学习部署：Windows安装pycocotools报错解决方法1.pycocotools库的简介2.pycocotools安装的坑3.解决办法更多Ai资讯：公主号AiCharm本系列是作者在跑一些深度学习实例时，遇到的各种各样的问题及解决办法，希望能够帮助到大家。ERROR:Commanderroredoutwithexitstatus1:'D:\Anaconda3\python.exe'-u-c'importsys,setuptools,tokenize;sys.argv[0]='"'"'C:\\Users\\46653\\AppData\\Local\\Temp\\pip-instal