[BUG]: get_log_correlation_context returns {'trace_id': '0', 'span_id': '0'} after an exception within ThreadPoolExecutor

[dseegerzoro]

Tracer Version(s)

2.16.6

Python Version(s)

Python 3.11.7

Pip Version(s)

pip 24.2

Bug Report

I have a scenario where my logs are not being correlated to my traces. I have found that the output from tracer.get_log_correlation_context() is {'trace_id': '0', 'span_id': '0', 'service': '', 'version': '', 'env': ''}

I have a flask + gevent + gunicorn app that creates a new thread from ThreadPoolExecutor to make a network call.

I have noticed that when the network call fails from requests.exceptions.ConnectTimeout my logs within the exception handling do not have valid trace or span IDs.

I am only able to reproduce this when using ThreadPoolExecutor to create the separate thread. If I use threading.Thread the exception logging correctly gets the trace and span IDs.

Wondering why using ThreadPoolExecutor is causing this issue.

Reproduction Code

from gevent import monkey
monkey.patch_all()

from concurrent.futures.thread import ThreadPoolExecutor

import requests
from ddtrace import tracer
from flask import Flask

app = Flask(__name__)
session = requests.Session()
executor = ThreadPoolExecutor()


def to_be_run_in_thread():
    try:
        session.get('https://catfact.ninja/fact', timeout=0.01)
    except requests.RequestException:
        print('---Start Exception Context---')
        print(tracer.get_log_correlation_context())
        print('---End Exception Context---')


@app.route('/')
def hello_world():
    print(tracer.get_log_correlation_context())
    future = executor.submit(to_be_run_in_thread)
    future.result()
    return 'Completed!'

Application is run with
OBJC_DISABLE_INITIALIZE_FORK_SAFETY=YES DD_TRACE_DEBUG=true ddtrace-run gunicorn -k gevent 'fake_app:app'

Request to app with
curl http://127.0.0.1:5000

App Output

{'trace_id': '680004dd00000000be58214407178728', 'span_id': '15422056973920900502', 'service': 'flask', 'version': '', 'env': ''}
---Start Exception Context---
{'trace_id': '0', 'span_id': '0', 'service': '', 'version': '', 'env': ''}
---End Exception Context---

Error Logs

No response

Libraries in Use

My requirements.txt looks like

gevent>=23.7,<23.8
requests>=2.22.0,<3.0.0
ddtrace~=2.16.0
Flask==2.2.3
gunicorn>=20.0.4,<21.0.0
Werkzeug==2.2.3

Pip freeze output

bytecode==0.16.2
certifi==2025.1.31
charset-normalizer==3.4.1
click==8.1.8
ddtrace==2.16.6
Deprecated==1.2.18
envier==0.6.1
Flask==2.2.3
gevent==23.7.0
greenlet==3.2.0
gunicorn==20.1.0
idna==3.10
importlib_metadata==8.6.1
itsdangerous==2.2.0
Jinja2==3.1.6
MarkupSafe==3.0.2
opentelemetry-api==1.32.1
protobuf==6.30.2
requests==2.32.3
typing_extensions==4.13.2
urllib3==2.4.0
Werkzeug==2.2.3
wrapt==1.17.2
xmltodict==0.14.2
zipp==3.21.0
zope.event==5.0
zope.interface==7.2

Operating System

Darwin Kernel Version 23.4.0