shenhuaxin commented on issue #9257:
URL: https://github.com/apache/dubbo/issues/9257#issuecomment-968067153
将应用正常启动后， 使用 tc 命令模拟网络异常， 将zk服务端的包延时设置为了5秒钟， 复现了之前的情况。
将日志级别调整为debug , 发现在重连阶段，产生了大量的 WatchEvent 事件。
使用 arthas 的 watch 命令发现，
ZooKeeper#getChildWatches 有3500个，
ZooKeeper#getDataWatches 也有3500个。
但是查看zk中的dubbo接口，总共只有280个左右，而本应用依赖的接口只有6个（本应用为consumer)。
```java
2021-11-12 21:26:12 | siac | | main-EventThread | DEBUG |
o.apache.curator.framework.recipes.cache.TreeCache | | TreeCache.java:341 |
process: WatchedEvent state:Disconnected type:None path:null
```
Event事件打印完毕之后就是打印ConnLoss错误日志
```java
2021-11-12 21:26:13 | siac | evcard-goods-back | Curator-Framework-0 | ERROR
| o.a.curator.framework.imps.CuratorFrameworkImpl | |
CuratorFrameworkImpl.java:557 | Background operation retry gave up
org.apache.zookeeper.KeeperException$ConnectionLossException:
KeeperErrorCode = ConnectionLoss
at org.apache.zookeeper.KeeperException.create(KeeperException.java:99)
at
org.apache.curator.framework.imps.CuratorFrameworkImpl.checkBackgroundRetry(CuratorFrameworkImpl.java:728)
at
org.apache.curator.framework.imps.CuratorFrameworkImpl.performBackgroundOperation(CuratorFrameworkImpl.java:857)
at
org.apache.curator.framework.imps.CuratorFrameworkImpl.backgroundOperationsLoop(CuratorFrameworkImpl.java:809)
at
org.apache.curator.framework.imps.CuratorFrameworkImpl.access$300(CuratorFrameworkImpl.java:64)
at
org.apache.curator.framework.imps.CuratorFrameworkImpl$4.call(CuratorFrameworkImpl.java:267)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
at
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
```
上述两个步骤不断的执行，如果 EventThread 中的 waitingEvents队列的消费速度跟不上生产速度，最终导致了OOM。
将dubbo版本调整到 2.7.9 之后，发现这种日志少了很多。
具体的原因没找出来 (=_=)
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