<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/incubator-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/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: xxx</li>
<li>Operating System version: xxx</li>
<li>Java version: xxx</li>
</ul>
<h3 dir="auto">Steps to reproduce this issue</h3>
<ol dir="auto">
<li>xxx</li>
<li>xxx</li>
<li>xxx</li>
</ol>
<p dir="auto">Pls. provide [GitHub address] to reproduce this issue.</p>
<h3 dir="auto">Expected Result</h3>
<p dir="auto">What do you expected from the above steps？</p>
<h3 dir="auto">Actual Result</h3>
<p dir="auto">What actually happens?</p>
<p dir="auto">If there is an exception, please attach the exception trace:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="Just put your stack trace here!"><pre class="notranslate"><code class="notranslate">Just put your stack trace here!
</code></pre></div>
<p dir="auto">Dubbo USES redis as the registry times error below:</p>
<p dir="auto">Exception in thread "main" java.lang.IllegalStateException: No such extension org.apache.dubbo.registry.RegistryFactory by name dubbo<br>
at org.apache.dubbo.common.extension.ExtensionLoader.findException(ExtensionLoader.java:499)<br>
at org.apache.dubbo.common.extension.ExtensionLoader.createExtension(ExtensionLoader.java:506)<br>
at org.apache.dubbo.common.extension.ExtensionLoader.getExtension(ExtensionLoader.java:325)<br>
at org.apache.dubbo.registry.RegistryFactory$Adaptive.getRegistry(RegistryFactory$Adaptive.java)<br>
at org.apache.dubbo.registry.integration.RegistryProtocol.getRegistry(RegistryProtocol.java:204)<br>
at org.apache.dubbo.registry.integration.RegistryProtocol.export(RegistryProtocol.java:138)<br>
at org.apache.dubbo.rpc.protocol.ProtocolListenerWrapper.export(ProtocolListenerWrapper.java:55)<br>
at org.apache.dubbo.rpc.protocol.ProtocolFilterWrapper.export(ProtocolFilterWrapper.java:98)<br>
at org.apache.dubbo.rpc.Protocol$Adaptive.export(Protocol$Adaptive.java)<br>
at org.apache.dubbo.config.ServiceConfig.doExportUrlsFor1Protocol(ServiceConfig.java:512)<br>
at org.apache.dubbo.config.ServiceConfig.doExportUrls(ServiceConfig.java:357)<br>
at org.apache.dubbo.config.ServiceConfig.doExport(ServiceConfig.java:316)<br>
at org.apache.dubbo.config.ServiceConfig.export(ServiceConfig.java:215)<br>
at org.apache.dubbo.config.spring.ServiceBean.onApplicationEvent(ServiceBean.java:114)<br>
at org.apache.dubbo.config.spring.ServiceBean.onApplicationEvent(ServiceBean.java:49)<br>
at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172)<br>
at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165)<br>
at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)<br>
at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:393)<br>
at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:347)<br>
at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:883)<br>
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:546)<br>
at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:139)<br>
at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:93)<br>
at org.apache.dubbo.demo.provider.Provider.main(Provider.java:29)<br>
[02/11/18 06:53:02:002 CST] main  WARN extension.ExtensionLoader:  [DUBBO] Failed to find extension named redis for type org.apache.dubbo.registry.RegistryFactory, will use default extension dubbo instead., dubbo version: , current host: 192.168.0.142<br>
java.lang.IllegalStateException: No such extension org.apache.dubbo.registry.RegistryFactory by name redis<br>
at org.apache.dubbo.common.extension.ExtensionLoader.findException(ExtensionLoader.java:499)<br>
at org.apache.dubbo.common.extension.ExtensionLoader.createExtension(ExtensionLoader.java:506)<br>
at org.apache.dubbo.common.extension.ExtensionLoader.getExtension(ExtensionLoader.java:325)<br>
at org.apache.dubbo.registry.RegistryFactory$Adaptive.getRegistry(RegistryFactory$Adaptive.java)<br>
at org.apache.dubbo.registry.integration.RegistryProtocol.getRegistry(RegistryProtocol.java:204)<br>
at org.apache.dubbo.registry.integration.RegistryProtocol.export(RegistryProtocol.java:138)<br>
at org.apache.dubbo.rpc.protocol.ProtocolListenerWrapper.export(ProtocolListenerWrapper.java:55)<br>
at org.apache.dubbo.rpc.protocol.ProtocolFilterWrapper.export(ProtocolFilterWrapper.java:98)<br>
at org.apache.dubbo.rpc.Protocol$Adaptive.export(Protocol$Adaptive.java)<br>
at org.apache.dubbo.config.ServiceConfig.doExportUrlsFor1Protocol(ServiceConfig.java:512)<br>
at org.apache.dubbo.config.ServiceConfig.doExportUrls(ServiceConfig.java:357)<br>
at org.apache.dubbo.config.ServiceConfig.doExport(ServiceConfig.java:316)<br>
at org.apache.dubbo.config.ServiceConfig.export(ServiceConfig.java:215)<br>
at org.apache.dubbo.config.spring.ServiceBean.onApplicationEvent(ServiceBean.java:114)<br>
at org.apache.dubbo.config.spring.ServiceBean.onApplicationEvent(ServiceBean.java:49)<br>
at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172)<br>
at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165)<br>
at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)<br>
at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:393)<br>
at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:347)<br>
at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:883)<br>
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:546)<br>
at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:139)<br>
at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:93)<br>
at org.apache.dubbo.demo.provider.Provider.main(Provider.java:29)</p>
<p dir="auto">I don't understand the core reason for this error. So I can't find the reason,and  I hope to get the answer . Thanks.</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/incubator-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/incubator-dubbo/wiki/FAQ">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: 2.5.3</li>
<li>Operating System version: xxx</li>
<li>Java version: 1.7</li>
</ul>
<p dir="auto">Dubbo admin同步zookeeper服务延迟比较长，请问这是什么原因？？？困扰了好久</p>