feat(tracing): spans not sent to agent after tracer shut down (#3483) (#3518)

Warns users when Tracer.trace() or Tracer.start_span() is called after a tracer is shutdown.

Co-authored-by: Munir Abdinur <[email protected]>

Author: mergify[bot]

ddtrace/tracer.py

@@ -35,7 +35,6 @@
 from .internal import debug
 from .internal import forksafe
 from .internal import hostname
-from .internal import service
 from .internal.dogstatsd import get_dogstatsd_client
 from .internal.logger import get_logger
 from .internal.logger import hasHandlers
@@ -46,6 +45,7 @@
 from .internal.processor.trace import TraceTagsProcessor
 from .internal.processor.trace import TraceTopLevelSpanProcessor
 from .internal.runtime import get_runtime_id
+from .internal.service import ServiceStatusError
 from .internal.utils.formats import asbool
 from .internal.writer import AgentWriter
 from .internal.writer import LogWriter
@@ -332,8 +332,8 @@ def configure(
 
         try:
             self._writer.stop()
-        except service.ServiceStatusError:
-            # It's possible the writer never got started in the first place :(
+        except ServiceStatusError:
+            # It's possible the writer never got started
             pass
 
         if writer is not None:
@@ -394,7 +394,20 @@ def _child_after_fork(self):
 
         self._new_process = True
 
-    def start_span(
+    def _start_span_after_shutdown(
+        self,
+        name,  # type: str
+        child_of=None,  # type: Optional[Union[Span, Context]]
+        service=None,  # type: Optional[str]
+        resource=None,  # type: Optional[str]
+        span_type=None,  # type: Optional[str]
+        activate=False,  # type: bool
+    ):
+        # type: (...) -> Span
+        log.warning("Spans started after the tracer has been shut down will not be sent to the Datadog Agent.")
+        return self._start_span(name, child_of, service, resource, span_type, activate)
+
+    def _start_span(
         self,
         name,  # type: str
         child_of=None,  # type: Optional[Union[Span, Context]]
@@ -589,6 +602,8 @@ def start_span(
         self._hooks.emit(self.__class__.start_span, span)
         return span
 
+    start_span = _start_span
+
     def _on_span_finish(self, span):
         # type: (Span) -> None
         active = self.current_span()
@@ -878,6 +893,8 @@ def shutdown(self, timeout=None):
             atexit.unregister(self._atexit)
             forksafe.unregister(self._child_after_fork)
 
+        self.start_span = self._start_span_after_shutdown  # type: ignore[assignment]
+
     @staticmethod
     def _use_log_writer():
         # type: () -> bool

releasenotes/notes/add-warning-after-shutdown-tracer-dd8799467c4d29c8.yaml

@@ -0,0 +1,4 @@
+---
+upgrade:
+  - |
+    Spans started after the tracer has been shut down will no longer be sent to the Datadog Agent.

tests/contrib/gevent/test_monkeypatch.py

@@ -24,7 +24,8 @@ def test_gevent_warning(monkeypatch):
 def test_gevent_auto_patching():
     import ddtrace
 
-    ddtrace.patch_all()
+    # Disable tracing sqlite3 as it is used by coverage
+    ddtrace.patch_all(sqlite3=False)
     # Patch on import
     import gevent  # noqa
 

tests/tracer/test_tracer.py

@@ -571,6 +571,21 @@ def test_tracer_shutdown():
     mock_write.assert_not_called()
 
 
+def test_tracer_shutdown_warning():
+    t = ddtrace.Tracer()
+    t.shutdown()
+
+    with mock.patch.object(logging.Logger, "warning") as mock_logger:
+        with t.trace("something"):
+            pass
+
+    mock_logger.assert_has_calls(
+        [
+            mock.call("Spans started after the tracer has been shut down will not be sent to the Datadog Agent."),
+        ]
+    )
+
+
 def test_tracer_dogstatsd_url():
     t = ddtrace.Tracer()
     assert t._writer.dogstatsd.host == "localhost"