Throwing an exception in case glibc is missing instead of segfaulting the JVM

It seems Netty’s native support depends on glibc (btw is this documented?). When glibc is missing (for example using vanilla Alpine), the JVM could end up with a crash (SIGSEGV), see details in this issue: https://github.com/micrometer-metrics/micrometer/issues/2776

It also seems that Epoll.isAvailable() returns true even if glibc is missing.

Expected behavior

Throwing an exception

Actual behavior

JVM crash

Steps to reproduce

Using Netty native with an environment that does not have glibc, e.g.: vanilla Alpine

Minimal yet complete reproducer code (or URL to code)

This seems to be a known issue, please let me know if you really need a reproducer.

Netty version

4.1.68 (latest)

JVM version (e.g. java -version)

Latest 11:

 ❯ docker run --rm 'azul/zulu-openjdk-alpine:11-jre' 'sh' '-c' 'java --version'
openjdk 11.0.12 2021-07-20 LTS
OpenJDK Runtime Environment Zulu11.50+19-CA (build 11.0.12+7-LTS)
OpenJDK 64-Bit Server VM Zulu11.50+19-CA (build 11.0.12+7-LTS, mixed mode)

Or also latest 17:

 ❯ docker run --rm 'bellsoft/liberica-openjdk-alpine-musl:17' 'sh' '-c' 'java --version'
openjdk 17 2021-09-14 LTS
OpenJDK Runtime Environment (build 17+35-LTS)
OpenJDK 64-Bit Server VM (build 17+35-LTS, mixed mode)

I assume this is an issue in every JRE that is currently supported.

OS version (e.g. uname -a)

Both images above have the same output:

 ❯ docker run --rm 'azul/zulu-openjdk-alpine:11-jre' 'sh' '-c' 'uname -a'
Linux 1ee8d1090f14 5.10.47-linuxkit #1 SMP Sat Jul 3 21:51:47 UTC 2021 x86_64 Linux

I assume this is an issue in every OS where glibc is missing.

[normanmaurer]

reopened

[chrisvest]

I have updated the documentation on the native transports to note that musl is not officially supported: https://github.com/netty/netty/wiki/Native-transports

I think that’s the best we can do for now.