Post k8s-events properly from multiple threads (thread-safe)

kopf/engines/logging.py

@@ -31,10 +31,6 @@ class K8sPoster(logging.Handler):
     A handler to post all log messages as K8s events.
     """
 
-    def __init__(self, level=logging.NOTSET, queue=None):
-        super().__init__(level=level)
-        self.queue = queue
-
     def createLock(self):
         # Save some time on unneeded locks. Events are posted in the background.
         # We only put events to the queue, which is already lock-protected.
@@ -59,11 +55,11 @@ def emit(self, record):
                 logging.getLevelName(record.levelno).capitalize())
             reason = 'Logging'
             message = self.format(record)
-            self.queue.put_nowait(posting.K8sEvent(
+            posting.enqueue(
                 ref=record.k8s_ref,
                 type=type,
                 reason=reason,
-                message=message))
+                message=message)
         except Exception:
             self.handleError(record)
 
@@ -84,8 +80,8 @@ class ObjectLogger(logging.LoggerAdapter):
     (e.g. in case of background posting via the queue; see `K8sPoster`).
     """
 
-    def __init__(self, *, body, event_level=logging.INFO, event_queue=None):
-        super().__init__(self._make_logger(event_level, event_queue), dict(
+    def __init__(self, *, body):
+        super().__init__(logger, dict(
             k8s_skip=False,
             k8s_ref=dict(
                 apiVersion=body.get('apiVersion'),
@@ -95,39 +91,6 @@ def __init__(self, *, body, event_level=logging.INFO, event_queue=None):
                 namespace=body.get('metadata', {}).get('namespace'),
             ),
         ))
-        self.queue = event_queue  # for kopf.event()&co explicit posting
-
-    def __del__(self):
-        # When an object logger is garbage-collected, purge its handlers & posting queues.
-        # Note: Depending on the garbage collection setup, this can never happen or be delayed.
-        # In this case, the object logger stays ready to log, i.e. keeps its handler+queue.
-        # TODO: also remove the dynamic logger itself, to avoid memory leaks.
-        for handler in list(self.logger.handlers):
-            if isinstance(handler, K8sPoster):
-                self.logger.removeHandler(handler)
-                handler.close()
-
-    def _make_logger(self, event_level, event_queue):
-        """
-        Get-or-create a logger for this event queue, and setup the k8s poster.
-
-        If only one global queue is used, it will be one logger.
-
-        If multiple queues are used, each queue uses its own logger
-        with its own handler. This is currently needed for tests
-        (every test provides and later asserts its own k8s-event queue).
-
-        In the future, or now via user tweaks, the framework can create
-        separate k8s-event-queues per resource kind, per individual objects,
-        or on another grouping basis. They should not duplicate each other
-        by posting the same log-message to k8s more than once.
-        For this purpose, separate `logging.Logger` instances are used:
-        strictly one per an `ObjectLogger` instance, dynamically created.
-        """
-        logger = logging.getLogger(f'kopf.objects.{id(event_queue)}')
-        if not logger.handlers:
-            logger.addHandler(K8sPoster(level=event_level, queue=event_queue))
-        return logger
 
     def process(self, msg, kwargs):
         # Native logging overwrites the message's extra with the adapter's extra.
@@ -139,3 +102,7 @@ def log(self, level, msg, *args, local=False, **kwargs):
         if local:
             kwargs['extra'] = dict(kwargs.pop('extra', {}), k8s_skip=True)
         super().log(level, msg, *args, **kwargs)
+
+
+logger = logging.getLogger('kopf.objects')
+logger.addHandler(K8sPoster(level=logging.INFO))

kopf/engines/posting.py

@@ -24,6 +24,10 @@
 from kopf.structs import dicts
 from kopf.structs import hierarchies
 
+# Logging and event-posting can happen cross-thread: e.g. in sync-executors.
+# We have to remember our main event-loop with the queue consumer, to make
+# thread-safe coro calls both from inside that event-loop and from outside.
+event_queue_loop_var: ContextVar[asyncio.AbstractEventLoop] = ContextVar('event_queue_loop_var')
 event_queue_var: ContextVar[asyncio.Queue] = ContextVar('event_queue_var')
 
 
@@ -38,12 +42,35 @@ class K8sEvent(NamedTuple):
     message: Text
 
 
-def event(objs, *, type, reason, message=''):
+def enqueue(ref, type, reason, message):
+    loop = event_queue_loop_var.get()
     queue = event_queue_var.get()
+    event = K8sEvent(ref=ref, type=type, reason=reason, message=message)
+
+    # Events can be posted from another thread than the event-loop's thread
+    # (e.g. from sync-handlers, or from explicitly started per-object threads),
+    # or from the same thread (async-handlers and the framework itself).
+    try:
+        running_loop = asyncio.get_running_loop()
+    except RuntimeError:
+        running_loop = None
+
+    if running_loop is loop:
+        # Posting from the same event-loop as the poster task and queue are in.
+        # Therefore, it is the same thread, and all calls here are thread-safe.
+        # Special thread-safe cross-event-loop methods make no effect here.
+        queue.put_nowait(event)
+    else:
+        # No event-loop or another event-loop - assume another thread.
+        # Use the cross-thread thread-safe methods. Block until enqueued there.
+        future = asyncio.run_coroutine_threadsafe(queue.put(event), loop=loop)
+        future.result()  # block, wait, re-raise.
+
+
+def event(objs, *, type, reason, message=''):
     for obj in dicts.walk(objs):
         ref = hierarchies.build_object_reference(obj)
-        event = K8sEvent(ref=ref, type=type, reason=reason, message=message)
-        queue.put_nowait(event)
+        enqueue(ref=ref, type=type, reason=reason, message=message)
 
 
 def info(obj, *, reason, message=''):

kopf/reactor/handling.py

@@ -89,7 +89,8 @@ async def custom_object_handler(
     patch = {}
 
     # Each object has its own prefixed logger, to distinguish parallel handling.
-    logger = logging_engine.ObjectLogger(body=body, event_queue=event_queue)
+    logger = logging_engine.ObjectLogger(body=body)
+    posting.event_queue_loop_var.set(asyncio.get_running_loop())
     posting.event_queue_var.set(event_queue)  # till the end of this object's task.
 
     # If the global freeze is set for the processing (i.e. other operator overrides), do nothing.

tests/posting/conftest.py

@@ -0,0 +1,24 @@
+import asyncio
+
+import pytest
+
+from kopf.engines.posting import event_queue_var, event_queue_loop_var
+
+
+@pytest.fixture()
+def event_queue_loop(event_loop):
+    token = event_queue_loop_var.set(event_loop)
+    try:
+        yield event_loop
+    finally:
+        event_queue_loop_var.reset(token)
+
+
+@pytest.fixture()
+def event_queue(event_loop):
+    queue = asyncio.Queue(loop=event_loop)
+    token = event_queue_var.set(queue)
+    try:
+        yield queue
+    finally:
+        event_queue_var.reset(token)

tests/posting/test_log2k8s.py

@@ -1,5 +1,3 @@
-import asyncio
-
 import pytest
 
 from kopf.engines.logging import ObjectLogger
@@ -16,14 +14,14 @@
     ['error', "Error"],
     ['critical', "Fatal"],
 ])
-def test_posting_normal_levels(caplog, logstream, logfn, event_type):
-    queue = asyncio.Queue()
-    logger = ObjectLogger(body=OBJ1, event_queue=queue)
+async def test_posting_normal_levels(caplog, logstream, logfn, event_type, event_queue, event_queue_loop):
+    logger = ObjectLogger(body=OBJ1)
+    logger_fn = getattr(logger, logfn)
 
-    getattr(logger, logfn)("hello %s", "world")
+    logger_fn("hello %s", "world")
 
-    assert queue.qsize() == 1
-    event1 = queue.get_nowait()
+    assert event_queue.qsize() == 1
+    event1 = event_queue.get_nowait()
     assert event1.ref == REF1
     assert event1.type == event_type
     assert event1.reason == "Logging"
@@ -34,14 +32,15 @@ def test_posting_normal_levels(caplog, logstream, logfn, event_type):
 @pytest.mark.parametrize('logfn', [
     'debug',
 ])
-def test_skipping_debug_level(caplog, logstream, logfn):
-    queue = asyncio.Queue()
-    logger = ObjectLogger(body=OBJ1, event_queue=queue)
+async def test_skipping_hidden_levels(caplog, logstream, logfn, event_queue, event_queue_loop):
+    logger = ObjectLogger(body=OBJ1)
+    logger_fn = getattr(logger, logfn)
 
-    getattr(logger, logfn)("hello %s", "world")
+    logger_fn("hello %s", "world")
+    logger.info("must be here")
 
-    assert queue.empty()
-    assert caplog.messages == ["hello world"]
+    assert event_queue.qsize() == 1  # not 2!
+    assert caplog.messages == ["hello world", "must be here"]
 
 
 @pytest.mark.parametrize('logfn', [
@@ -51,11 +50,12 @@ def test_skipping_debug_level(caplog, logstream, logfn):
     'error',
     'critical',
 ])
-def test_skipping_when_local_with_all_level(caplog, logstream, logfn):
-    queue = asyncio.Queue()
-    logger = ObjectLogger(body=OBJ1, event_queue=queue)
+async def test_skipping_when_local_with_all_levels(caplog, logstream, logfn, event_queue, event_queue_loop):
+    logger = ObjectLogger(body=OBJ1)
+    logger_fn = getattr(logger, logfn)
 
-    getattr(logger, logfn)("hello %s", "world", local=True)
+    logger_fn("hello %s", "world", local=True)
+    logger.info("must be here")
 
-    assert queue.empty()
-    assert caplog.messages == ["hello world"]
+    assert event_queue.qsize() == 1  # not 2!
+    assert caplog.messages == ["hello world", "must be here"]

tests/posting/test_poster.py

@@ -4,7 +4,7 @@
 from asynctest import call
 
 from kopf import event, info, warn, exception
-from kopf.engines.posting import poster, K8sEvent, event_queue_var
+from kopf.engines.posting import poster, K8sEvent, event_queue_var, event_queue_loop_var
 
 OBJ1 = {'apiVersion': 'group1/version1', 'kind': 'Kind1',
         'metadata': {'uid': 'uid1', 'name': 'name1', 'namespace': 'ns1'}}
@@ -42,7 +42,7 @@ def _cancel(*args, **kwargs):
     )
 
 
-def test_queueing_fails_with_no_queue(mocker):
+def test_queueing_fails_with_no_queue(event_queue_loop):
     # Prerequisite: the context-var should not be set by anything in advance.
     sentinel = object()
     assert event_queue_var.get(sentinel) is sentinel
@@ -51,11 +51,18 @@ def test_queueing_fails_with_no_queue(mocker):
         event(OBJ1, type='type1', reason='reason1', message='message1')
 
 
-def test_via_event_function(mocker):
+def test_queueing_fails_with_no_loop(event_queue):
+    # Prerequisite: the context-var should not be set by anything in advance.
+    sentinel = object()
+    assert event_queue_loop_var.get(sentinel) is sentinel
+
+    with pytest.raises(LookupError):
+        event(OBJ1, type='type1', reason='reason1', message='message1')
+
+
+async def test_via_event_function(mocker, event_queue, event_queue_loop):
     post_event = mocker.patch('kopf.clients.events.post_event')
 
-    event_queue = asyncio.Queue()
-    event_queue_var.set(event_queue)
     event(OBJ1, type='type1', reason='reason1', message='message1')
 
     assert not post_event.called
@@ -74,11 +81,9 @@ def test_via_event_function(mocker):
     pytest.param(warn, "Warning", id='warn'),
     pytest.param(exception, "Error", id='exception'),
 ])
-def test_via_shortcut(mocker, event_fn, event_type):
+async def test_via_shortcut(mocker, event_fn, event_type, event_queue, event_queue_loop):
     post_event = mocker.patch('kopf.clients.events.post_event')
 
-    event_queue = asyncio.Queue()
-    event_queue_var.set(event_queue)
     event_fn(OBJ1, reason='reason1', message='message1')
 
     assert not post_event.called