A lot of log will be output and consumed a lot of CPU after network is disconnected on Android devices

I have a trouble about netty when I use micronaut on Android. And I reported an issue to micronaut(https://github.com/micronaut-projects/micronaut-core/issues/4129). But they tell me that I should report the issue to netty.

Expected behavior

Micronaut server stopped normally.

Actual behavior

Micronaut server will be stopped, but a lot of log will be output. And this will take up a lot of CPU resource. Log:

 [nioEventLoopGroup-1-1] WARN io.netty.channel.nio.NioEventLoop - Selector.select() returned prematurely 512 times in a row; rebuilding Selector io.netty.channel.nio.SelectedSelectionKeySetSelector@70c8d50.
2020-09-18 14:58:18.405 25846-25923/com.example.androidwebtest I/System.out: 14:58:18.405 [nioEventLoopGroup-1-1] INFO io.netty.channel.nio.NioEventLoop - Migrated 1 channel(s) to the new Selector.
2020-09-18 14:58:18.406 25846-25923/com.example.androidwebtest I/System.out: 14:58:18.406 [nioEventLoopGroup-1-1] WARN io.netty.channel.nio.NioEventLoop - Selector.select() returned prematurely 512 times in a row; rebuilding Selector io.netty.channel.nio.SelectedSelectionKeySetSelector@1a42c4e.
2020-09-18 14:58:18.407 25846-25923/com.example.androidwebtest I/System.out: 14:58:18.407 [nioEventLoopGroup-1-1] INFO io.netty.channel.nio.NioEventLoop - Migrated 1 channel(s) to the new Selector.
2020-09-18 14:58:18.409 25846-25923/com.example.androidwebtest I/System.out: 14:58:18.408 [nioEventLoopGroup-1-1] WARN io.netty.channel.nio.NioEventLoop - Selector.select() returned prematurely 512 times in a row; rebuilding Selector io.netty.channel.nio.SelectedSelectionKeySetSelector@8352e7c.
2020-09-18 14:58:18.409 25846-25923/com.example.androidwebtest I/System.out: 14:58:18.409 [nioEventLoopGroup-1-1] INFO io.netty.channel.nio.NioEventLoop - Migrated 1 channel(s) to the new Selector.
2020-09-18 14:58:18.411 25846-25923/com.example.androidwebtest I/System.out: 14:58:18.410 [nioEventLoopGroup-1-1] WARN io.netty.channel.nio.NioEventLoop - Selector.select() returned prematurely 512 times in a row; rebuilding Selector io.netty.channel.nio.SelectedSelectionKeySetSelector@21abf5a.
2020-09-18 14:58:18.411 25846-25923/com.example.androidwebtest I/System.out: 14:58:18.411 [nioEventLoopGroup-1-1] INFO io.netty.channel.nio.NioEventLoop - Migrated 1 channel(s) to the new Selector.
2020-09-18 14:58:18.413 25846-25923/com.example.androidwebtest I/System.out: 14:58:18.413 [nioEventLoopGroup-1-1] WARN io.netty.channel.nio.NioEventLoop - Selector.select() returned prematurely 512 times in a row; rebuilding Selector io.netty.channel.nio.SelectedSelectionKeySetSelector@2e4b668.
2020-09-18 14:58:18.413 25846-25923/com.example.androidwebtest I/System.out: 14:58:18.413 [nioEventLoopGroup-1-1] INFO io.netty.channel.nio.NioEventLoop - Migrated 1 channel(s) to the new Selector.
2020-09-18 14:58:18.415 25846-25923/com.example.androidwebtest I/System.out: 14:58:18.414 [nioEventLoopGroup-1-1] WARN io.netty.channel.nio.NioEventLoop - Selector.select() returned prematurely 512 times in a row; rebuilding Selector io.netty.channel.nio.SelectedSelectionKeySetSelector@7357726.
2020-09-18 14:58:18.415 25846-25923/com.example.androidwebtest I/System.out: 14:58:18.415 [nioEventLoopGroup-1-1] INFO io.netty.channel.nio.NioEventLoop - Migrated 1 channel(s) to the new Selector.
2020-09-18 14:58:18.417 25846-25923/com.example.androidwebtest I/System.out: 14:58:18.417 [nioEventLoopGroup-1-1] WARN io.netty.channel.nio.NioEventLoop - Selector.select() returned prematurely 512 times in a row; rebuilding Selector io.netty.channel.nio.SelectedSelectionKeySetSelector@482d114.
2020-09-18 14:58:18.417 25846-25923/com.example.androidwebtest I/System.out: 14:58:18.417 [nioEventLoopGroup-1-1] INFO io.netty.channel.nio.NioEventLoop - Migrated 1 channel(s) to the new Selector.
......

CPU:

Tasks: 785 total,   4 running, 780 sleeping,   0 stopped,   1 zombie
  Mem:      5.4G total,      5.3G used,      116M free,      175M buffers
 Swap:      2.5G total,      498M used,      2.0G free,      3.0G cached
800%cpu  81%user  14%nice 196%sys 490%idle   0%iow  16%irq   3%sirq   0%host
  PID USER         PR  NI VIRT  RES  SHR S[%CPU] %MEM     TIME+ ARGS
25846 u0_a219      10 -10 5.3G 130M  79M S 99.3   2.3   0:15.86 com.example.androidwebtest

Steps to reproduce

1. Start micronaut and listen the IP of WiFi, but not listen “0.0.0.0”.
2. Disconect WiFi.

Minimal yet complete reproducer code (or URL to code)

https://github.com/igiantpanda/AndroidWebTest/tree/disconnect-issue

Netty version

4.1.48.Final (The corresponding version of Micronaut is 2.0.0)

JVM version (e.g. java -version)

1.8

OS version (e.g. uname -a)

Android 10 (Tested on Android emulator and OPPO Reno)

[hyperxpro]

Turn off logging for io.netty.channel.nio.NioEventLoop

I hope that this is a joke. There must be a bug in Netty that causes these messages in the first place.

There is no bug in Netty but in Java NIO. So apart from turn off logging, you can switch to Epoll mechanism. Else, no other option. 😃

[hyperxpro]

Turn off logging for io.netty.channel.nio.NioEventLoop