Do not initialize logging on import

conftest.py

@@ -18,6 +18,10 @@
     except Exception:
         pass
 
+from distributed.config import ensure_logging_configured
+
+ensure_logging_configured()
+
 # Make all fixtures available
 from distributed.utils_test import *  # noqa
 

distributed/config.py

@@ -4,6 +4,7 @@
 import logging.config
 import os
 import sys
+import threading
 from collections.abc import Callable
 from typing import Any
 
@@ -212,4 +213,13 @@ def get_loop_factory() -> Callable[[], asyncio.AbstractEventLoop] | None:
     )
 
 
-initialize_logging(dask.config.config)
+_LOGGING_CONFIGURED = False
+_LOG_CONFIGURE_LOCK = threading.Lock()
+
+
+def ensure_logging_configured() -> None:
+    global _LOGGING_CONFIGURED
+    with _LOG_CONFIGURE_LOCK:
+        if not _LOGGING_CONFIGURED:
+            _LOGGING_CONFIGURED = True
+            initialize_logging(dask.config.config)

distributed/core.py

@@ -45,6 +45,7 @@
 )
 from distributed.comm.core import Listener
 from distributed.compatibility import PeriodicCallback
+from distributed.config import ensure_logging_configured
 from distributed.counter import Counter
 from distributed.diskutils import WorkDir, WorkSpace
 from distributed.metrics import context_meter, time
@@ -647,6 +648,7 @@ async def start_unsafe(self):
 
     @final
     async def start(self):
+        ensure_logging_configured()
         async with self._startup_lock:
             if self.status == Status.failed:
                 assert self.__startup_exc is not None

distributed/deploy/cluster.py

@@ -16,6 +16,7 @@
 from dask.widgets import get_template
 
 from distributed.compatibility import PeriodicCallback
+from distributed.config import ensure_logging_configured
 from distributed.core import Status
 from distributed.deploy.adaptive import Adaptive
 from distributed.metrics import time
@@ -67,6 +68,7 @@ def __init__(
         name=None,
         scheduler_sync_interval=1,
     ):
+        ensure_logging_configured()
         self._loop_runner = LoopRunner(loop=loop, asynchronous=asynchronous)
         self.__asynchronous = asynchronous
 

distributed/tests/test_config.py

@@ -84,6 +84,8 @@ def test_logging_simple_under_distributed():
             import logging
             import dask
 
+            from distributed.config import ensure_logging_configured
+            ensure_logging_configured()
             from distributed.utils_test import captured_handler
 
             d = logging.getLogger('distributed')
@@ -116,6 +118,8 @@ def test_logging_simple():
             import logging
             import dask
 
+            from distributed.config import ensure_logging_configured
+            ensure_logging_configured()
             from distributed.utils_test import captured_handler
 
             d = logging.getLogger('distributed')
@@ -172,6 +176,8 @@ def test_logging_extended():
         code = """if 1:
             import logging
 
+            from distributed.config import ensure_logging_configured
+            ensure_logging_configured()
             from distributed.utils_test import captured_handler
 
             root = logging.getLogger()
@@ -205,6 +211,8 @@ def test_default_logging_does_not_override_basic_config():
         import logging
         logging.basicConfig()
         import distributed
+        from distributed.config import ensure_logging_configured
+        ensure_logging_configured()
         logging.getLogger("distributed").warning("hello")
         """
     )
@@ -220,7 +228,8 @@ def test_basic_config_does_not_override_default_logging():
         """\
         import logging
         import distributed
-
+        from distributed.config import ensure_logging_configured
+        ensure_logging_configured()
         logging.basicConfig()
         logging.getLogger("distributed").warning("hello")
         """
@@ -287,7 +296,8 @@ def test_logging_file_config():
     with new_config_file(dask_config):
         code = """if 1:
             import logging
-            from distributed import config
+            from distributed.config import ensure_logging_configured
+            ensure_logging_configured()
             foo = logging.getLogger('foo')
             bar = logging.getLogger('foo.bar')
             assert logging.INFO == foo.getEffectiveLevel()

distributed/utils.py

@@ -54,7 +54,7 @@
 import tblib.pickling_support
 
 from distributed.compatibility import asyncio_run
-from distributed.config import get_loop_factory
+from distributed.config import ensure_logging_configured, get_loop_factory
 
 try:
     import resource
@@ -893,6 +893,7 @@ def silence_logging_cmgr(
     """
     Temporarily change all StreamHandlers for the given logger to the given level
     """
+    ensure_logging_configured()
     if isinstance(level, str):
         level = getattr(logging, level.upper())