You’re hitting Prefect’s API log worker shutting down while there are still log records in its queue. During pytest teardown it logs “Still processing items: N items remaining…” while draining. It’s harmless, but noisy—especially if you call

get_run_logger()

in many tasks. Two easy ways to silence it in Prefect 3.x: Option A — Disable API logging during tests (recommended) - Keeps logs in local stdout/stderr; avoids the background API log worker entirely.

# conftest.py
import pytest
from prefect.settings import (
    temporary_settings,
    PREFECT_LOGGING_TO_API_ENABLED,
    PREFECT_LOGGING_TO_API_WHEN_MISSING_FLOW,
)

@pytest.fixture(autouse=True)
def disable_prefect_api_logging():
    # Prevent the API log handler from starting in tests
    with temporary_settings(
        updates={
            PREFECT_LOGGING_TO_API_ENABLED: False,
            # Avoid warnings if get_run_logger is used outside a run context
            PREFECT_LOGGING_TO_API_WHEN_MISSING_FLOW: "ignore",
        }
    ):
        yield

If you prefer environment variables, you can export these before running pytest:

PREFECT_LOGGING_TO_API_ENABLED=false
PREFECT_LOGGING_TO_API_WHEN_MISSING_FLOW=ignore

Option B — Keep API logging, but flush/drain the worker at teardown - If you need API logging in tests, make sure the queue is drained cleanly.

# conftest.py
import asyncio
import pytest
from prefect.logging.handlers import APILogHandler, APILogWorker

@pytest.fixture(scope="session", autouse=True)
def drain_prefect_log_workers_on_exit():
    yield
    # Ensure everything is flushed before pytest exits
    asyncio.run(APILogHandler.aflush())
    asyncio.run(APILogWorker.drain_all())

Tips - If you directly call task functions (outside a flow context), also set

PREFECT_LOGGING_TO_API_WHEN_MISSING_FLOW=ignore

to suppress extra warnings. - To capture run logs in tests, prefer

LogEavesdropper

or add the caplog handler to

prefect.flow_runs

/

prefect.task_runs

instead of relying on the API handler. If you can share your Prefect version and whether you want logs shipped to the Prefect API during tests, I can tailor the fixture exactly to your setup.

Got it — Prefect 3.5.0 and you don’t want logs shipped to the Prefect API during tests. That warning is from the API log worker shutting down with items still in its queue. The clean fix is to disable API logging in tests and (for safety) drain any worker that a test might have started. Pick one of these: Option 1: Set env vars before pytest (simplest)

export PREFECT_LOGGING_TO_API_ENABLED=false
export PREFECT_LOGGING_TO_API_WHEN_MISSING_FLOW=ignore
pytest

Option 2: Conftest fixtures (project-local and robust)

# conftest.py
import asyncio
import pytest
from prefect.settings import (
    temporary_settings,
    PREFECT_LOGGING_TO_API_ENABLED,
    PREFECT_LOGGING_TO_API_WHEN_MISSING_FLOW,
)
from prefect.logging.handlers import APILogHandler, APILogWorker

@pytest.fixture(autouse=True)
def disable_prefect_api_logging():
    # Prevent the API log handler from running during tests
    with temporary_settings(
        updates={
            PREFECT_LOGGING_TO_API_ENABLED: False,
            # Suppress warnings if get_run_logger is used without a run context
            PREFECT_LOGGING_TO_API_WHEN_MISSING_FLOW: "ignore",
        }
    ):
        yield

@pytest.fixture(scope="session", autouse=True)
def drain_prefect_log_workers_on_exit():
    # Ensure any worker started by a test is fully drained to avoid warnings
    yield
    asyncio.run(APILogHandler.aflush())
    asyncio.run(APILogWorker.drain_all())

Notes - This will keep your

get_run_logger()

logs local (stdout/stderr) and silence the “Still processing items…” warning. - If you ever need API logging for a specific test, wrap that test body with:

from prefect.settings import temporary_settings, PREFECT_LOGGING_TO_API_ENABLED

  with temporary_settings(updates={PREFECT_LOGGING_TO_API_ENABLED: True}):
      # run the test code that should ship logs