codelipenghui opened a new issue #7804:
URL: https://github.com/apache/pulsar/issues/7804
**Describe the bug**
```
java.util.ConcurrentModificationException: null
at
java.util.ArrayList$SubList.checkForComodification(ArrayList.java:1241)
~[?:1.8.0_265]
at java.util.ArrayList$SubList.size(ArrayList.java:1050) ~[?:1.8.0_265]
at
org.apache.pulsar.broker.service.Consumer.lambda$sendMessages$0(Consumer.java:267)
~[org.apache.pulsar-pulsar-broker-2.6.0-sn-12.jar:2.6.0-sn-12]
at
io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
[io.netty-netty-common-4.1.48.Final.jar:4.1.48.Final]
at
io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
[io.netty-netty-common-4.1.48.Final.jar:4.1.48.Final]
at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:387)
[io.netty-netty-transport-native-epoll-4.1.48.Final-linux-x86_64.jar:4.1.48.Final]
at
io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
[io.netty-netty-common-4.1.48.Final.jar:4.1.48.Final]
at
io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
[io.netty-netty-common-4.1.48.Final.jar:4.1.48.Final]
at
io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
[io.netty-netty-common-4.1.48.Final.jar:4.1.48.Final]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_265]
```
**To Reproduce**
It's hard to reproduce.
**Expected behavior**
Keep the list operation safely.
**Additional context**
Add any other context about the problem here.
----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
For queries about this service, please contact Infrastructure at:
[email protected]
