Parent IDs are null for spawned spans with gevent auto-instrumentation

[CagriYonca]

Describe your environment

OS: MacOS
Python version: 3.12.4
telemetry.sdk.version: 1.28.2
telemetry.auto.version: 0.49b2

What happened?

I'm trying to use auto-instrument with gevent, but the parent ids are null for spawned spans. Am I missing anything or do you have any suggestion?

Steps to Reproduce

Server Code

from gevent import monkey

monkey.patch_all()

from flask import Flask, request

app = Flask(__name__)


@app.route("/server_request")
def server_request():
    print(request.args.get("param"))
    return "served"


if __name__ == "__main__":
    app.run(port=8082)

• Run with:
  opentelemetry-instrument --traces_exporter console --metrics_exporter none python server_automatic.py

Client Code

import gevent

from sys import argv

from requests import get

from opentelemetry import trace
from opentelemetry.propagate import inject
from opentelemetry.sdk.trace import TracerProvider
from opentelemetry.sdk.trace.export import (
    BatchSpanProcessor,
    ConsoleSpanExporter,
)
from opentelemetry.instrumentation.requests import RequestsInstrumentor

RequestsInstrumentor().instrument()

trace.set_tracer_provider(TracerProvider())
tracer = trace.get_tracer_provider().get_tracer(__name__)

trace.get_tracer_provider().add_span_processor(
    BatchSpanProcessor(ConsoleSpanExporter())
)

assert len(argv) == 2


def make_http_call(n=None):
    headers = {}
    inject(headers)
    return get(
        "http://localhost:8082/server_request",
        params={"param": argv[1]},
        headers=headers,
    )


def spawn_calls():
    with tracer.start_as_current_span("spawn_calls"):
        jobs = []
        jobs.append(gevent.spawn(make_http_call))
        jobs.append(gevent.spawn(make_http_call))
        jobs.append(gevent.spawn(make_http_call))
        gevent.joinall(jobs, timeout=2)


def launch_gevent_chain():
    with tracer.start_as_current_span("test"):
        gevent.spawn(spawn_calls).join()


gevent.spawn(launch_gevent_chain)

gevent.sleep(2)

• Run with:
  python client.py otel-flask-gevent-testing

Expected Result

I was expecting to see spawn_calls's span id as spawned spans' pids.

Actual Result

Parent IDs in the results are null

Additional context

No response

Would you like to implement a fix?

None

[aabmass]

Thanks for the clear bug description. We've had a few questions related to gevent lately but I don't think we explicitly support it today. We use the builtin contextvars module for propagating parent information which already works nicely with sync and asyncio call stacks.

Does gevent work with contextvars?