- [ ] I have searched the [issues](https://github.com/apache/dubbo/issues) of this repository and believe that this is not a duplicate. - [ ] I have checked the [FAQ](https://github.com/apache/dubbo/blob/master/FAQ.md) of this repository and believe that this is not a duplicate.
### Environment * Dubbo version: 2.7.3 * Operating System version: macOs Sierra * Java version: 1.8 ### Steps to reproduce this issue 服务端启动后，20880端口正常打开，客户端在端口打开后偶尔会报connect timeout的现象，从网络来看有丢SYN包的情况，主要是由于accept queue满了导致的。 1. 服务端机器的配置不是很高，应用启动过程需要消耗大量CPU初始化工作。 2. 客户端多线程并发发起到服务端的连接，每秒钟发起几百上千个连接请求。 3. 在服务端机器看到有accept queue满的情况。 ``` 3220 times the listen queue of a socket overflowed 3220 SYNs to LISTEN sockets dropped ``` 4. 通过查看当前端口的连接队列，只有50个，也就是netty3的默认backlog，实际队列最高是101个。 ``` [~]# ss -lnt State Recv-Q Send-Q Local Address:Port Peer Address:Port LISTEN 0 50 *:20880 *:* ``` Netty4的默认backlog也是1000，所以把Netty3的默认backlog调整成1024. [ Full content available at: https://github.com/apache/dubbo/issues/5168 ] This message was relayed via gitbox.apache.org for notifications@dubbo.apache.org
--------------------------------------------------------------------- To unsubscribe, e-mail: notifications-unsubscr...@dubbo.apache.org For additional commands, e-mail: notifications-h...@dubbo.apache.org
