extractIncludeProto deadlocks

[michaelliau]

We are encountering consistent build timeouts in CI related to what appears to be deadlock during parallel execution of the extractIncludeProto task. We've cleaned up our usage of the plugin as a result of the errors but we're still seeing a relatively high rate of failures (15%).

Here are the relevant plugin configuration portions from our convention:

plugins {
    id("com.google.protobuf")
}

protobuf {
    protoc {
        val protobufVersion = extensionLibs.findLibrary("google.protobuf").orElseThrow().get().version
        artifact = "com.google.protobuf:protoc:${protobufVersion}"
    }
    plugins {
        id("grpc") {
            val grpcVersion = extensionLibs.findLibrary("grpc.protobuf").orElseThrow().get().version
            artifact = "io.grpc:protoc-gen-grpc-java:${grpcVersion}"
        }
    }
    generateProtoTasks {
        all().forEach { task ->
            task.builtins {
                id("python") { }
            }
            task.plugins {

                id("grpc") {
                    outputSubDir = "java"
                }
            }
        }
    }
}

We have 3 projects that appear to get stuck in every build failure (timeout due to no progress):

> Task :hummingbird:interfaces:dmz:customer:extractIncludeProto
> Task :hummingbird:interfaces:dmz:quoting:extractIncludeProto
> Task :hummingbird:interfaces:dmz:user:extractIncludeProto

Two of the projects do not include any external protos but one does include common google types (timestamp, date, money, etc). There are no dependencies between these projects - each should build independently of the others.

Any insight on what could be happening here and steps to remedy?