Compilation docs no longer work in latest grpc-java

[pkwarren]

What version of gRPC-Java are you using?

v1.56.0

What is your environment?

MacOS/Linux arm64

What did you expect to see?

Following instructions in COMPILING.md should result in a successful build.

What did you see instead?

https://github.com/grpc/grpc-java/blob/f3399e3d0e52c4c20409de3b4435fea12bec12c6/COMPILING.md#how-to-build-code-generation-plugin refers to the protobuf-all artifact, which is no longer shipped with newer releases (grpc-java requires protoc 22.3). It also refers to using autotools to build protoc from source, which is no longer supported (ref: https://protobuf.dev/news/2022-08-03/).

Steps to reproduce the bug

Attempt to follow the steps in COMPILING.md to build grpc-java (including the compiler).

[pkwarren]

It looks like #10048 will fix most of these issues (when merged).

[ejona86]

Ugh, yeah. The trick right now is Java is depending on 22.3, but we are still using 21.x for c++. Do the instructions work if you try and use the older version?

[pkwarren]

Ugh, yeah. The trick right now is Java is depending on 22.3, but we are still using 21.x for c++. Do the instructions work if you try and use the older version?

Good to know. I got confused by this while building:

> Configure project :grpc-compiler
*** Building codegen requires Protobuf version 3.22.3

I managed to get it building with the current instructions (although I had to set org.gradle.jvmargs=-Xmx4g in gradle.properties to get xds code to build as the default 1g wasn't enough).

[ejona86]

*** Building codegen requires Protobuf version 3.22.3

Oh... I know how that happened. I think I'm just going to delete the version in that message. Most of the time you can use an older version without issue.

although I had to set org.gradle.jvmargs=-Xmx4g in gradle.properties to get xds code to build as the default 1g wasn't enough

"Fork javac to avoid OOM" in #10299 may fix that. We've been fighting OOM for a while on the CI; I'm hopeful we've tracked down the major source.