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autocomplete="off" placeholder="搜索..." spellcheck="false" type="text" id="local-search-input"></div></div><div id="local-search-result"></div></div></div></nav></div></header><main id="main" class="main"><div class="main-inner"><div class="content-wrap"><div id="content" class="content"><div id="posts" class="posts-expand"><article class="post post-type-normal" itemscope itemtype="http://schema.org/Article"><div class="post-block"><link itemprop="mainEntityOfPage" href="https://www.playpi.org/2018122702.html"><span hidden itemprop="author" itemscope itemtype="http://schema.org/Person"><meta itemprop="name" content="虾丸派"><meta itemprop="description" content="记录知识 | 分享技术"><meta itemprop="image" content="/images/favicon-1536x1536-playpi.png"></span><span hidden itemprop="publisher" itemscope itemtype="http://schema.org/Organization"><meta itemprop="name" content="虾丸派"></span><header class="post-header"><h2 class="post-title" itemprop="name headline">HDFS 异常之 READ is not supported in state standby</h2><div class="post-meta"><span class="post-time"><span class="post-meta-item-text">发表于</span> <time title="创建于" itemprop="dateCreated datePublished" datetime="2018-12-27T19:06:42+08:00">2018-12-27 </time></span><span class="post-category"><span class="post-meta-divider">|</span> <span class="post-meta-item-text">分类于</span> <span itemprop="about" itemscope itemtype="http://schema.org/Thing"><a href="/categories/series-of-hadoop/" itemprop="url" rel="index"><span itemprop="name">Hadoop 从零基础到入门系列</span> </a></span></span><span id="busuanzi_container_page_pv" style="display:none"><span class="post-meta-divider">|</span> 阅读次数 <span id="busuanzi_value_page_pv"></span></span><div class="post-wordcount"><span class="post-meta-item-text">字数统计</span> <span title="字数统计">2,069字 </span><span class="post-meta-divider">|</span> <span class="post-meta-item-text">阅读时长 ≈</span> <span title="阅读时长">9分钟</span></div></div></header><div class="post-body" itemprop="articleBody"><p>今天查看日志发现，以前正常运行的 Spark 程序会不断抛出异常：<br></p><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">org.apache.hadoop.ipc.RemoteException (org.apache.hadoop.ipc.StandbyException): Operation category READ is not supported in state standby</span><br></pre></td></tr></table></figure><p></p><p>但是却没有影响到功能的正常运行，只不过是抛出了大量的上述异常，而且内容都一样，也都是操作 HDFS 产生的，所以猜测与 HDFS 集群（或者配置）有关系。本文就记录发现问题、解决问题的过程。</p><a id="more"></a><h1 id="问题出现"><a href="# 问题出现" class="headerlink" title="问题出现"></a>问题出现</h1><p>按照日常操作，查看 Spark 任务的 Driver 端的日志，结果发现了大量的重复异常，又看了一下对功能的影响，结果发现没有影响，所有功能均正常运行，产生的结果也是期望的。</p><h2 id="问题分析"><a href="# 问题分析" class="headerlink" title="问题分析"></a>问题分析</h2><p>详细来看一下 Driver 端的日志异常信息：</p><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br></pre></td><td class="code"><pre><span class="line">2018-12-26_23:25:40 [main] INFO retry.RetryInvocationHandler:140: Exception while invoking getFileInfo of class ClientNamenodeProtocolTranslatorPB over hadoop1/192.168.10.162:8020. Trying to fail over immediately.</span><br><span class="line">org.apache.hadoop.ipc.RemoteException (org.apache.hadoop.ipc.StandbyException): Operation category READ is not supported in state standby</span><br><span class="line"> at org.apache.hadoop.hdfs.server.namenode.ha.StandbyState.checkOperation (StandbyState.java:<span class="number">87</span>)</span><br><span class="line"> at org.apache.hadoop.hdfs.server.namenode.NameNode$NameNodeHAContext.checkOperation (NameNode.java:<span class="number">1722</span>)</span><br><span class="line"> at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkOperation (FSNamesystem.java:<span class="number">1362</span>)</span><br><span class="line"> at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getFileInfo (FSNamesystem.java:<span class="number">4414</span>)</span><br><span class="line"> at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.getFileInfo (NameNodeRpcServer.java:<span class="number">893</span>)</span><br><span class="line"> at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.getFileInfo (ClientNamenodeProtocolServerSideTranslatorPB.java:<span class="number">835</span>)</span><br><span class="line"> at org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$<span class="number">2</span>.callBlockingMethod (ClientNamenodeProtocolProtos.java)</span><br><span class="line"> at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call (ProtobufRpcEngine.java:<span class="number">619</span>)</span><br><span class="line"> at org.apache.hadoop.ipc.RPC$Server.call (RPC.java:<span class="number">962</span>)</span><br><span class="line"> at org.apache.hadoop.ipc.Server$Handler$<span class="number">1</span>.run (Server.java:<span class="number">2039</span>)</span><br><span class="line"> at org.apache.hadoop.ipc.Server$Handler$<span class="number">1</span>.run (Server.java:<span class="number">2035</span>)</span><br><span class="line"> at java.security.AccessController.doPrivileged (Native Method)</span><br><span class="line"> at javax.security.auth.Subject.doAs (Subject.java:<span class="number">422</span>)</span><br><span class="line"> at org.apache.hadoop.security.UserGroupInformation.doAs (UserGroupInformation.java:<span class="number">1628</span>)</span><br><span class="line"> at org.apache.hadoop.ipc.Server$Handler.run (Server.java:<span class="number">2033</span>)</span><br><span class="line"> at org.apache.hadoop.ipc.Client.call (Client.java:<span class="number">1468</span>)</span><br><span class="line"> at org.apache.hadoop.ipc.Client.call (Client.java:<span class="number">1399</span>)</span><br><span class="line"> at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke (ProtobufRpcEngine.java:<span class="number">232</span>)</span><br><span class="line"> at com.sun.proxy.$Proxy30.getFileInfo (Unknown Source)</span><br><span class="line"> at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.getFileInfo (ClientNamenodeProtocolTranslatorPB.java:<span class="number">768</span>)</span><br><span class="line"> at sun.reflect.GeneratedMethodAccessor34.invoke (Unknown Source)</span><br><span class="line"> at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:<span class="number">43</span>)</span><br><span class="line"> at java.lang.reflect.Method.invoke (Method.java:<span class="number">498</span>)</span><br><span class="line"> at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod (RetryInvocationHandler.java:<span class="number">187</span>)</span><br><span class="line"> at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke (RetryInvocationHandler.java:<span class="number">102</span>)</span><br><span class="line"> at com.sun.proxy.$Proxy31.getFileInfo (Unknown Source)</span><br><span class="line"> at org.apache.hadoop.hdfs.DFSClient.getFileInfo (DFSClient.java:<span class="number">2007</span>)</span><br><span class="line"> at org.apache.hadoop.hdfs.DistributedFileSystem$<span class="number">19</span>.doCall (DistributedFileSystem.java:<span class="number">1136</span>)</span><br><span class="line"> at org.apache.hadoop.hdfs.DistributedFileSystem$<span class="number">19</span>.doCall (DistributedFileSystem.java:<span class="number">1132</span>)</span><br><span class="line"> at org.apache.hadoop.fs.FileSystemLinkResolver.resolve (FileSystemLinkResolver.java:<span class="number">81</span>)</span><br><span class="line"> at org.apache.hadoop.hdfs.DistributedFileSystem.getFileStatus (DistributedFileSystem.java:<span class="number">1132</span>)</span><br><span class="line"> at org.apache.hadoop.fs.FileSystem.isFile (FileSystem.java:<span class="number">1426</span>)</span><br></pre></td></tr></table></figure><p>注意一下核心异常所在：<br></p><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">Exception while invoking getFileInfo of class ClientNamenodeProtocolTranslatorPB over hadoop1/192.168.10.162:8020. Trying to fail over immediately.</span><br><span class="line">org.apache.hadoop.ipc.RemoteException (org.apache.hadoop.ipc.StandbyException): Operation category READ is not supported in state standby</span><br></pre></td></tr></table></figure><p></p><p>当去从 hadoop1/192.168.10.162:8020 这里 getFileInfo 的时候，抛出了异常，而且明确告诉我们这台机器处于 standby 状态，不支持读取操作。此时，可以想到，肯定是 hadoop1/192.168.10.162:8020 这台机器已经处于 standby 状态了，无法提供服务，所以抛出此异常。既然问题找到了，那么问题产生的原因是什么呢，以及为什么对功能没有影响，接下来一一分析。</p><p>首先查看 hdfs-site.xml 配置文件，看看 namenode 相关的配置项：</p><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag"><<span class="name">property</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">name</span>></span>dfs.nameservices<span class="tag"></<span class="name">name</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">value</span>></span>r-cluster<span class="tag"></<span class="name">value</span>></span></span><br><span class="line"><span class="tag"></<span class="name">property</span>></span></span><br><span class="line"></span><br><span class="line"><span class="tag"><<span class="name">property</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">name</span>></span>dfs.ha.namenodes.r-cluster<span class="tag"></<span class="name">name</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">value</span>></span>nn1,nn2<span class="tag"></<span class="name">value</span>></span></span><br><span class="line"><span class="tag"></<span class="name">property</span>></span></span><br><span class="line"></span><br><span class="line"><span class="tag"><<span class="name">property</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">name</span>></span>dfs.namenode.rpc-address.r-cluster.nn1<span class="tag"></<span class="name">name</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">value</span>></span>hadoop1:8020<span class="tag"></<span class="name">value</span>></span></span><br><span class="line"><span class="tag"></<span class="name">property</span>></span></span><br><span class="line"></span><br><span class="line"><span class="tag"><<span class="name">property</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">name</span>></span>dfs.namenode.rpc-address.r-cluster.nn2<span class="tag"></<span class="name">name</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">value</span>></span>rocket15:8020<span class="tag"></<span class="name">value</span>></span></span><br><span class="line"><span class="tag"></<span class="name">property</span>></span></span><br></pre></td></tr></table></figure><p>可以看到，namenode 相关配置有 2 台机器：nn1、nn2，而上述产生异常的信息表明连接 nn1 被拒绝，那么我去看一下 HDFS 集群的状态，发现 nn1 果然是 standby 状态的，而 nn2（rocket15） 才是 active 状态。</p><p><img src="https://raw.githubusercontent.com/iplaypi/img-playpi/master/img/old/b7f2e3a3gy1fyluqlzruwj20ln0b6mxq.jpg" alt="nn2 的 active 状态" title="nn2 的 active 状态"></p><p>再仔细查看日志，没有发现连接 nn2 的异常，那就说明是第一次连接 nn1 抛出异常，然后试图连接 nn2，成功连接，没有抛出异常，接下来程序就正常处理数据了，对功能没有任何影响。</p><p>到这里，我们已经分析出了整个过程，现象表明这个异常只是连接了 standby 状态的 namenode，是正常抛出的。然后会再次连接另外一台 active 状态的 namenode，连接成功。</p><h2 id="抛异常的流程细节"><a href="# 抛异常的流程细节" class="headerlink" title="抛异常的流程细节"></a>抛异常的流程细节</h2><p>1、客户端在连接 HDFS 的时候，会从配置文件 hdfs-site.xml 中，读取 nameservices 的配置，获取机器编号，我这里是 nn1 和 nn2，分别对应着 2 台 namenode 机器；</p><p>2、客户端会首先选择编号较小的 namenode（我这里是 nn1，对应着 hadoop1），试图连接；</p><p>3、如果这台 namenode 是 active 状态，则客户端可以正常处理请求；但是如果这台 namenode 是 standby 状态，则客户端抛出由服务端返回的异常：Operation category READ is not supported in state standby，同时打印 ip 信息，接着会尝试连接另外一台编号较大的 namenode（我这里是 nn2，即 rocket15）；</p><p>4、如果连接成功，则客户端可以正常处理请求；如果 nn2 仍然像 nn1 一样，客户端会抛出一样的异常，此时会继续反复重试 nn1 与 nn2（重试次数有配置项，间隔时间有配置项）；如果有成功的，则客户端可以正常处理请求，如果全部失败，则客户端无法正常处理请求，此时应该要关注解决 namenode 为什么全部都处在 standby 状态。</p><p>配置参数如下（参考 <a href="https://hadoop.apache.org/docs/r2.6.0/hadoop-project-dist/hadoop-hdfs/hdfs-default.xml" target="_blank" rel="noopener">Hadoop 官方文档 </a>）：</p><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment"><!-- 客户端重试次数，默认 15 --></span></span><br><span class="line"><span class="tag"><<span class="name">property</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">name</span>></span>dfs.client.failover.max.attempts<span class="tag"></<span class="name">name</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">value</span>></span>15<span class="tag"></<span class="name">value</span>></span></span><br><span class="line"><span class="tag"></<span class="name">property</span>></span></span><br><span class="line"></span><br><span class="line"><span class="comment"><!-- 客户端 2 次重试间隔时间，默认 500 毫秒 --></span></span><br><span class="line"><span class="tag"><<span class="name">property</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">name</span>></span>dfs.client.failover.sleep.base.millis<span class="tag"></<span class="name">name</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">value</span>></span>500<span class="tag"></<span class="name">value</span>></span></span><br><span class="line"><span class="tag"></<span class="name">property</span>></span></span><br><span class="line"></span><br><span class="line"><span class="comment"><!-- 客户端 2 次重试间隔时间，默认 1500 毫秒 --></span></span><br><span class="line"><span class="tag"><<span class="name">property</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">name</span>></span>dfs.client.failover.sleep.max.millis<span class="tag"></<span class="name">name</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">value</span>></span>1500<span class="tag"></<span class="name">value</span>></span></span><br><span class="line"><span class="tag"></<span class="name">property</span>></span></span><br><span class="line"></span><br><span class="line"><span class="comment"><!-- 客户端 1 次连接中重试次数，默认 0, 在网络不稳定时建议加大此值 --></span></span><br><span class="line"><span class="tag"><<span class="name">property</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">name</span>></span>dfs.client.failover.connection.retries<span class="tag"></<span class="name">name</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">value</span>></span>0<span class="tag"></<span class="name">value</span>></span></span><br><span class="line"><span class="tag"></<span class="name">property</span>></span></span><br><span class="line"></span><br><span class="line"><span class="comment"><!-- 客户端 1 次连接中超时重试次数，仅是指超时重试，默认 0, 在网络不稳定时建议加大此值 --></span></span><br><span class="line"><span class="tag"><<span class="name">property</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">name</span>></span>dfs.client.failover.connection.retries.on.timeouts<span class="tag"></<span class="name">name</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">value</span>></span>0<span class="tag"></<span class="name">value</span>></span></span><br><span class="line"><span class="tag"></<span class="name">property</span>></span></span><br></pre></td></tr></table></figure><h1 id="问题解决"><a href="# 问题解决" class="headerlink" title="问题解决"></a> 问题解决</h1><p>既然明确了问题，并且分析出了具体原因，解决起来就简单了，对于我这种情况，有 2 种方法：</p><p>1、不用解决，也无需关心，这个异常没有任何影响，会自动重连另外一台 active 状态的 namenode 机器的；</p><p>2、如果就是一心想把异常消除掉，那就更改 hdfs-site.xml 配置文件里面的 nameservices 配置项对应的机器，把编号最小的机器设置成状态为 active 的 namenode（例如我这里把 nn1、nn2 的对应的机器 ip 地址交换一下即可，确保 nn1 是 active 状态的），那么连接 HDFS 的时候第一次就会直接连接这台机器，就不会抛出异常了（但是要注意 namenode 以后可能是会挂的，挂了会自动切换，那么到那个时候还要更改这个配置项）。</p><figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag"><<span class="name">property</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">name</span>></span>dfs.namenode.rpc-address.r-cluster.nn1<span class="tag"></<span class="name">name</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">value</span>></span>rocket15:8020<span class="tag"></<span class="name">value</span>></span></span><br><span class="line"><span class="tag"></<span class="name">property</span>></span></span><br><span class="line"></span><br><span class="line"><span class="tag"><<span class="name">property</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">name</span>></span>dfs.namenode.rpc-address.r-cluster.nn2<span class="tag"></<span class="name">name</span>></span></span><br><span class="line"> <span class="tag"><<span class="name">value</span>></span>hadoop1:8020<span class="tag"></<span class="name">value</span>></span></span><br><span class="line"><span class="tag"></<span class="name">property</span>></span></span><br></pre></td></tr></table></figure><h1 id="问题总结"><a href="# 问题总结" class="headerlink" title="问题总结"></a>问题总结</h1><p>1、参考：<a href="http://support-it.huawei.com/docs/zh-cn/fusioninsight-all/maintenance-guide/zh-cn_topic_0062904132.html" target="_blank" rel="noopener">http://support-it.huawei.com/docs/zh-cn/fusioninsight-all/maintenance-guide/zh-cn_topic_0062904132.html</a></p><p>2、这个问题其实不是问题，只不过抛出了异常，我看到有点担心而已，但是如果连接所有的机器都抛出这种异常，并且重试了很多次就有影响了，说明所有的 namenode 都挂了，根本无法正常操作 HDFS 系统；</p><p>3、根据 2 进行总结：如果只是在操作 HDFS 的时候打印一次（每次操作都会打印一次），说明第一次连接到了 standby 状态的 namenode，是正常的，不用关心；但是，如果出现了大量的异常（比如连续 10 次，连续 20 次），说明 namenode 出问题了，此时应该关心 namenode 的状态，确保正常服务。</p></div><div><div id="wechat_subscriber" style="display:block;padding:10px 0;margin:20px auto;width:100%;text-align:center"><img id="wechat_subscriber_qcode" src="/images/wechat-qr-personal.jpg" alt="虾丸派 wechat" style="width:200px;max-width:100%"><div>扫一扫添加博主，进技术交流群，共同学习进步</div></div></div><div><div 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