Investigate why `npm run init` hangs on jenkins

[cdesouza-chromium]

It is very unclear why this may happen, but once it starts happening, it occurs in a very consistent way. I have spun up a jenkins instance locally, and although I could reproduce it locally at first, once I got a pipeline going and fully cloned by jenkins, this failure started happening consistently. The basic gist is that npm run init hangs when calling gclient sync.

[cdesouza-chromium]

So, the basic summary of my investigation is:

This issue is specific to gclient sync with --revision being run on Jenkins, although the particulars are not very clear.

How to reproduce

Create a branch in brave-core and commit a jenkins pipeline that looks like this (e.g. tools/cr/brockit.groovy):

pipeline {
    agent any
    environment {
        CHROMIUM_SRC_PATH = "brave-browser/src/"
        BRAVE_CORE_PATH = "brave-browser/src/brave/"
        PATH = "${WORKSPACE}/${BRAVE_CORE_PATH}/vendor/depot_tools:${PATH}"
    }
    stages {
        stage('Initialise') {
            steps {
                dir("${BRAVE_CORE_PATH}") {
                    sh """
                    npm run init
                    """
                }
            }
        }
    }
}

Create a Jenkins pipeline with Pipeline script from SCM, provide the clone path to the necessary fields, in Branch Specifier type the exact name of the branch you pushed the pipeline to.

Add Additional Behaviours > Checkout to a sub-directory > and set the path to brave-browser/src/brave.

Enter the path in brave-core for the test pipeline file above (e.g. tools/cr/brockit.groovy)

The first run is supposed to be successful, until runhooks completes successfully for the first time. After that, all runs to npm run init will hang on gclient sync using --revision. In my tests, the issue only started happening once I had an npm run init run that was completely successful. I had to rerun the job a few times when I cloned the repo, as some deps were failing, and in that meantime I never got the hanging failure, until I had a full npm run init successful run.

Once the issue is apparent, it can be isolated to running:

gclient sync --nohooks --revision src@refs/tags/136.0.7081.1 --reset --upstream --force -D --verbose

I was not able to reproduce this issue when configuring the pipeline to be run inside jenkins itself, rather than from the repo.