如何找到 bazel 错误工作进程未返回 WorkResponse 的根本原因？

Question

My bazel v4.0.0. build just shows me this unclear Worker process did not return a WorkResponse error message which seems to hide the root cause of the problem. It happens when I include a processor in the java_library target.

This is a reduced version of my bazel BUILD file:

java_library(
    name="java",
    srcs=glob(["**/*.java"]),
    plugins = [
        ":my_processor",
    ],
)

java_plugin(
    name = "my_processor",
    processor_class = "mypackage.MyProcessor",
)

How to find out what is wrong?

Answer 1

Possibly there's more scenarios that could cause this error, my what worked for me as a is to specify --noexperimental_worker_multiplex .

The command bazel build //myproject/src/main/java --noexperimental_worker_multiplex changed the error message but most importantly it revealed: Did you try to print something to stdout?

And indeed the processor appeared to contain a System.out.println . Removing it resolved this build error.

Btw I did remove the --noexperimental_worker_multiplex after the problem was solved, because I think the experimental_worker_multiplex is a good thing.