<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have searched the <a href="https://github.com/apache/incubator-dubbo/issues">issues</a> of this repository and believe that this is not a duplicate.</li>
<li>[] I have checked the <a href="https://github.com/apache/incubator-dubbo/blob/master/FAQ.md">FAQ</a> of this repository and believe that this is not a duplicate.</li>
</ul>
<h3 dir="auto">Environment</h3>
<ul dir="auto">
<li>Dubbo version: master</li>
<li>Operating System version: deepin 15.9</li>
<li>Java version: 8</li>
</ul>
<p dir="auto">I want to know more about dubbo.And I found this code in module dubbo-metrics/dubbo-metrics-api/.../MetrcLevel</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="static {
        for (MetricLevel level : MetricLevel.values()) {
            if (level.ordinal() &lt; 0) {
                throw new RuntimeException(&quot;MetricLevel can not &lt; 0&quot;);
            }
        }
    }"><pre class="notranslate"><code class="notranslate">static {
        for (MetricLevel level : MetricLevel.values()) {
            if (level.ordinal() &lt; 0) {
                throw new RuntimeException("MetricLevel can not &lt; 0");
            }
        }
    }
</code></pre></div>
<p dir="auto">I think this code is futility.Is it possible of level.ordinal() &lt; 0?</p>
<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have searched the <a href="https://github.com/apache/dubbo/issues">issues</a> of this repository and believe that this is not a duplicate.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have checked the <a href="https://github.com/apache/dubbo/blob/master/FAQ.md">FAQ</a> of this repository and believe that this is not a duplicate.</li>
</ul>
<h3 dir="auto">Environment</h3>
<ul dir="auto">
<li>Dubbo version: 2.7.4.1</li>
<li>Operating System version: mac</li>
<li>Java version: 8</li>
</ul>
<h3 dir="auto">Steps to reproduce this issue</h3>
<h4 dir="auto">错误</h4>
<blockquote>
<p dir="auto">020-04-10 10:36:22.117  WARN 12008 --- [Report-thread-1] o.a.d.m.s.z.ZookeeperMetadataReport      :  [DUBBO] Failed to save service store file, cause: 文件名、目录名或卷标语法不正确。, dubbo version: 2.7.4.1.ZDUBBO-SNAPSHOT, current host: 10.45.19.17<br>
java.io.IOException: 文件名、目录名或卷标语法不正确。<br>
at java.io.WinNTFileSystem.createFileExclusively(Native Method) ~[na:1.8.0_101]<br>
at java.io.File.createNewFile(File.java:1012) ~[na:1.8.0_101]<br>
at org.apache.dubbo.metadata.support.AbstractMetadataReport.doSaveProperties(AbstractMetadataReport.java:144) [dubbo-2.7.4.1.ZDUBBO-SNAPSHOT.jar:2.7.4.1.ZDUBBO-SNAPSHOT]<br>
at org.apache.dubbo.metadata.support.AbstractMetadataReport.access$100(AbstractMetadataReport.java:70) [dubbo-2.7.4.1.ZDUBBO-SNAPSHOT.jar:2.7.4.1.ZDUBBO-SNAPSHOT]<br>
at org.apache.dubbo.metadata.support.AbstractMetadataReport$SaveProperties.run(AbstractMetadataReport.java:224) [dubbo-2.7.4.1.ZDUBBO-SNAPSHOT.jar:2.7.4.1.ZDUBBO-SNAPSHOT]<br>
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_101]<br>
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_101]<br>
at java.lang.Thread.run(Thread.java:745) [na:1.8.0_101]</p>
</blockquote>
<p dir="auto">配置zk地址配置成：127.0.0.1:2181,127.0.0.1:2182,127.0.0.1:2183就会出现，改成<br>
zookeeper://127.0.0.1:2181?backup=127.0.0.1:2182,127.0.0.1:2183 就好了</p>