@Marvin I have a Flow that within its logic calls

concurrent.futures.ThreadPoolExecutor()

and creates threads that launches another function. The problem is that the TaskRunContext is lost when creating the threads, what's the best way to pass and persist the TaskContext into the threads?

To pass and persist the

TaskRunContext

into threads when using

concurrent.futures.ThreadPoolExecutor()

, you can use the

ContextVar

from the

contextvars

module in Python. Prefect's context management can be leveraged by using context variables that are thread-local, allowing you to propagate the context into new threads. Here's a simple outline of how you might achieve this: 1. Define a Context Variable: Use

ContextVar

to define a variable that holds the context you want to propagate. 2. Set the Context in the Main Thread: Before you start the threads, set the context variable with the current context. 3. Pass the Context to Threads: When launching threads, pass the context variable to them, and set it inside the thread function. Here's a basic example:

python
import concurrent.futures
from contextvars import ContextVar
from prefect import flow, task

# Define a context variable
task_run_context_var = ContextVar('task_run_context')

def thread_function(context_value):
    # Set the context variable in the thread
    token = task_run_context_var.set(context_value)
    try:
        # Access the context within the thread
        context = task_run_context_var.get()
        print(f"Running in thread with context: {context}")
    finally:
        # Reset the context variable
        task_run_context_var.reset(token)

@task
def my_task():
    # Set the context variable in the main thread
    context_value = "TaskRunContextValue"
    task_run_context_var.set(context_value)

    with concurrent.futures.ThreadPoolExecutor() as executor:
        # Pass the context to the thread
        executor.submit(thread_function, context_value)

@flow
def my_flow():
    my_task()

my_flow()

This approach ensures that each thread starts with the context it needs, maintaining the intended behavior. You can refer to Prefect's context management for more details on how contexts are managed within Prefect.