2 questions 1 Is there a recepie how multiple pants run coul Pants #general

2 questions: (1) Is there a recepie how multiple ...

fancy-photographer-78161

06/20/2023, 10:02 AM

2 questions: (1) Is there a recepie how multiple “pants run”… could be ran concurrently? (2) Is there a way to auto-refresh “pants run” if something changed in code?

gorgeous-winter-99296

06/20/2023, 10:21 AM

1. Yes, using

PANTS_CONCURRENT=true

. See caveats here though: https://www.pantsbuild.org/docs/reference-global#concurrent 2. Yes, but depends on the target. On some targets you can set

restartable=True

in your BUILD file and it should work: https://www.pantsbuild.org/docs/reference-python_sources#coderestartablecode. I tend to to use a method which combines

pants --loop package ...

with another subprocess to pick up the produced artifact and runs it outside pants. It depends a bit on the semantics.

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gorgeous-winter-99296

06/20/2023, 10:29 AM

As an example; this is a shim we use to iterate on mdbook docs in our repo:

Copy code

import http.server
import os
import socketserver
import subprocess
import threading
from functools import partial

def pants(*args):
    return subprocess.check_output(
        [
            "pants",
            *args,
        ],
        env=os.environ
        | {
            "PANTS_CONCURRENT": "true",
        },
    )


class Server(socketserver.TCPServer):
    allow_reuse_address = True


def build_docs():
    pants("--loop", "package", "docs:docs")


def main():
    threading.Thread(target=build_docs).start()

    Handler = partial(http.server.SimpleHTTPRequestHandler, directory="dist/docs/book/")
    server = Server(("", 8000), Handler)
    server.allow_reuse_address = True

    with server as httpd:
        httpd.serve_forever()


main()

This technically isn't parallel, it's nested - we use

pants run scripts/docs.py

(through the alias

pants serve-docs

). The ones where we do use parallel work are much longer unfortunately. 😛

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