<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 class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> 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: 2.6.1</li>
<li>Operating System version: Linux version 3.10.0-693.el7.x86_64 (<a href="mailto:builder@kbuilder.dev.centos.org">builder@kbuilder.dev.centos.org</a>) (gcc version 4.8.5 20150623 (Red Hat 4.8.5-16) (GCC) )</li>
<li>Java version: 1.8.0_171</li>
<li>zk &amp; zk client version: 3.4.11</li>
<li>curator version: 4.0.1</li>
</ul>
<h3 dir="auto">不定时出现zookeeper session timeout，重连后消费端引用<a class="user-mention notranslate" data-hovercard-type="user" data-hovercard-url="/users/reference/hovercard" data-octo-click="hovercard-link-click" data-octo-dimensions="link_type:self" href="https://github.com/reference">@reference</a> 为空，日志如下</h3>
<h3 dir="auto">消费端jvm日志</h3>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="04:22:37,427  WARN [main-SendThread(hostname:2181)][zookeeper.ClientCnxn:1111] - Client session timed out, have not heard from server in 33959ms for sessionid 0x10000018d38000b
04:23:07,081  INFO [main-SendThread(hostname:2181)][zookeeper.ClientCnxn:1159] - Client session timed out, have not heard from server in 33959ms for sessionid 0x10000018d38000b, closing socket connection and attempting reconnect
04:23:09,992  INFO [main-EventThread][state.ConnectionStateManager:237] - State change: SUSPENDED
04:23:10,186  INFO [main-SendThread(hostname:2181)][zookeeper.ClientCnxn:1035] - Opening socket connection to server hostname/172.16.10.121:2181. Will not attempt to authenticate using SASL (unknown error)
04:23:10,804  INFO [main-SendThread(hostname:2181)][zookeeper.ClientCnxn:877] - Socket connection established to hostname/172.16.10.121:2181, initiating session
04:23:10,998  WARN [main-SendThread(hostname:2181)][zookeeper.ClientCnxn:1288] - Unable to reconnect to ZooKeeper service, session 0x10000018d38000b has expired
04:23:11,066  INFO [main-SendThread(hostname:2181)][zookeeper.ClientCnxn:1157] - Unable to reconnect to ZooKeeper service, session 0x10000018d38000b has expired, closing socket connection
04:23:11,164  WARN [main-EventThread][curator.ConnectionState:372] - Session expired event received
04:23:12,502  INFO [main-EventThread][zookeeper.ZooKeeper:441] - Initiating client connection, connectString=hostname:2181 sessionTimeout=60000 watcher=org.apache.curator.ConnectionState@67f639d3
04:23:13,599  INFO [main-SendThread(hostname:2181)][zookeeper.ClientCnxn:1035] - Opening socket connection to server hostname/172.16.10.121:2181. Will not attempt to authenticate using SASL (unknown error)
04:23:13,671  INFO [main-SendThread(hostname:2181)][zookeeper.ClientCnxn:877] - Socket connection established to hostname/172.16.10.121:2181, initiating session
04:23:13,771  INFO [main-SendThread(hostname:2181)][zookeeper.ClientCnxn:1302] - Session establishment complete on server hostname/172.16.10.121:2181, sessionid = 0x10000018d38002b, negotiated timeout = 40000
04:23:13,672  INFO [main-EventThread][state.ConnectionStateManager:237] - State change: LOST
04:23:13,960  INFO [main-EventThread][state.ConnectionStateManager:237] - State change: RECONNECTED
04:23:14,708  INFO [main-EventThread][zookeeper.ClientCnxn:520] - EventThread shut down for session: 0x10000018d38000b"><pre class="notranslate"><code class="notranslate">04:22:37,427  WARN [main-SendThread(hostname:2181)][zookeeper.ClientCnxn:1111] - Client session timed out, have not heard from server in 33959ms for sessionid 0x10000018d38000b
04:23:07,081  INFO [main-SendThread(hostname:2181)][zookeeper.ClientCnxn:1159] - Client session timed out, have not heard from server in 33959ms for sessionid 0x10000018d38000b, closing socket connection and attempting reconnect
04:23:09,992  INFO [main-EventThread][state.ConnectionStateManager:237] - State change: SUSPENDED
04:23:10,186  INFO [main-SendThread(hostname:2181)][zookeeper.ClientCnxn:1035] - Opening socket connection to server hostname/172.16.10.121:2181. Will not attempt to authenticate using SASL (unknown error)
04:23:10,804  INFO [main-SendThread(hostname:2181)][zookeeper.ClientCnxn:877] - Socket connection established to hostname/172.16.10.121:2181, initiating session
04:23:10,998  WARN [main-SendThread(hostname:2181)][zookeeper.ClientCnxn:1288] - Unable to reconnect to ZooKeeper service, session 0x10000018d38000b has expired
04:23:11,066  INFO [main-SendThread(hostname:2181)][zookeeper.ClientCnxn:1157] - Unable to reconnect to ZooKeeper service, session 0x10000018d38000b has expired, closing socket connection
04:23:11,164  WARN [main-EventThread][curator.ConnectionState:372] - Session expired event received
04:23:12,502  INFO [main-EventThread][zookeeper.ZooKeeper:441] - Initiating client connection, connectString=hostname:2181 sessionTimeout=60000 watcher=org.apache.curator.ConnectionState@67f639d3
04:23:13,599  INFO [main-SendThread(hostname:2181)][zookeeper.ClientCnxn:1035] - Opening socket connection to server hostname/172.16.10.121:2181. Will not attempt to authenticate using SASL (unknown error)
04:23:13,671  INFO [main-SendThread(hostname:2181)][zookeeper.ClientCnxn:877] - Socket connection established to hostname/172.16.10.121:2181, initiating session
04:23:13,771  INFO [main-SendThread(hostname:2181)][zookeeper.ClientCnxn:1302] - Session establishment complete on server hostname/172.16.10.121:2181, sessionid = 0x10000018d38002b, negotiated timeout = 40000
04:23:13,672  INFO [main-EventThread][state.ConnectionStateManager:237] - State change: LOST
04:23:13,960  INFO [main-EventThread][state.ConnectionStateManager:237] - State change: RECONNECTED
04:23:14,708  INFO [main-EventThread][zookeeper.ClientCnxn:520] - EventThread shut down for session: 0x10000018d38000b
</code></pre></div>
<h3 dir="auto">zookeeper服务器日志</h3>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="2018-09-12 02:36:05,355 [myid:] - INFO  [SessionTracker:ZooKeeperServer@354] - Expiring session 0x10000018dc20000, timeout of 40000ms exceeded
2018-09-12 02:36:05,356 [myid:] - INFO  [SessionTracker:ZooKeeperServer@354] - Expiring session 0x10000018dc20002, timeout of 40000ms exceeded
2018-09-12 02:36:05,356 [myid:] - INFO  [SessionTracker:ZooKeeperServer@354] - Expiring session 0x10000018dc20003, timeout of 40000ms exceeded
2018-09-12 02:36:05,356 [myid:] - INFO  [ProcessThread(sid:0 cport:2181)::PrepRequestProcessor@487] - Processed session termination for sessionid: 0x10000018dc20000
2018-09-12 02:36:05,356 [myid:] - INFO  [ProcessThread(sid:0 cport:2181)::PrepRequestProcessor@487] - Processed session termination for sessionid: 0x10000018dc20002
2018-09-12 02:36:05,357 [myid:] - INFO  [ProcessThread(sid:0 cport:2181)::PrepRequestProcessor@487] - Processed session termination for sessionid: 0x10000018dc20003
2018-09-12 02:39:41,884 [myid:] - INFO  [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:NIOServerCnxnFactory@215] - Accepted socket connection from /172.16.10.123:33164
2018-09-12 02:39:41,888 [myid:] - INFO  [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:ZooKeeperServer@938] - Client attempting to establish new session at /172.16.10.123:33164
2018-09-12 02:39:41,996 [myid:] - INFO  [SyncThread:0:ZooKeeperServer@683] - Established session 0x10000018d380001 with negotiated timeout 40000 for client /172.16.10.123:33164"><pre class="notranslate"><code class="notranslate">2018-09-12 02:36:05,355 [myid:] - INFO  [SessionTracker:ZooKeeperServer@354] - Expiring session 0x10000018dc20000, timeout of 40000ms exceeded
2018-09-12 02:36:05,356 [myid:] - INFO  [SessionTracker:ZooKeeperServer@354] - Expiring session 0x10000018dc20002, timeout of 40000ms exceeded
2018-09-12 02:36:05,356 [myid:] - INFO  [SessionTracker:ZooKeeperServer@354] - Expiring session 0x10000018dc20003, timeout of 40000ms exceeded
2018-09-12 02:36:05,356 [myid:] - INFO  [ProcessThread(sid:0 cport:2181)::PrepRequestProcessor@487] - Processed session termination for sessionid: 0x10000018dc20000
2018-09-12 02:36:05,356 [myid:] - INFO  [ProcessThread(sid:0 cport:2181)::PrepRequestProcessor@487] - Processed session termination for sessionid: 0x10000018dc20002
2018-09-12 02:36:05,357 [myid:] - INFO  [ProcessThread(sid:0 cport:2181)::PrepRequestProcessor@487] - Processed session termination for sessionid: 0x10000018dc20003
2018-09-12 02:39:41,884 [myid:] - INFO  [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:NIOServerCnxnFactory@215] - Accepted socket connection from /172.16.10.123:33164
2018-09-12 02:39:41,888 [myid:] - INFO  [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:ZooKeeperServer@938] - Client attempting to establish new session at /172.16.10.123:33164
2018-09-12 02:39:41,996 [myid:] - INFO  [SyncThread:0:ZooKeeperServer@683] - Established session 0x10000018d380001 with negotiated timeout 40000 for client /172.16.10.123:33164
</code></pre></div>
<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>Java version: 1.8</li>
</ul>
<h3 dir="auto">Actual Result</h3>
<p dir="auto"></p><div class="Box Box--condensed my-2">
  <div class="Box-header f6">
    <p class="mb-0 text-bold">
      <a href="https://github.com/apache/dubbo/blob/839d2a604e629ea9e96b964be09ae221e85312ba/dubbo-common/src/main/java/org/apache/dubbo/rpc/model/ApplicationModel.java#L80">dubbo/dubbo-common/src/main/java/org/apache/dubbo/rpc/model/ApplicationModel.java</a>
    </p>
    <p class="mb-0 color-fg-muted">
         Line 80
      in
      <a data-pjax="true" class="commit-tease-sha" href="/apache/dubbo/commit/839d2a604e629ea9e96b964be09ae221e85312ba">839d2a6</a>
    </p>
  </div>
  <div itemprop="text" class="Box-body p-0 blob-wrapper blob-wrapper-embedded data">
    <table class="highlight tab-size mb-0 js-file-line-container" data-tab-size="8" data-paste-markdown-skip="">

        <tbody><tr class="border-0">
          <td id="L80" class="blob-num border-0 px-3 py-0 color-bg-default" data-line-number="80"></td>
          <td id="LC80" class="blob-code border-0 px-3 py-0 color-bg-default blob-code-inner js-file-line"> <span class="pl-k">public</span> <span class="pl-k">static</span> <span class="pl-smi">void</span> <span class="pl-en">iniFrameworkExts</span>() { </td>
        </tr>
    </tbody></table>
  </div>
</div>
<p></p>
<h3 dir="auto">Expected Result</h3>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="initFrameworkExts"><pre class="notranslate"><code class="notranslate">initFrameworkExts
</code></pre></div>