ref(transactions): option for not doing transactions sampling in post…

…_process (#81079)

in lockstep with #81077, stops
doing work in post_process on transactions. part of
#81065

src/sentry/tasks/post_process.py

@@ -16,6 +16,7 @@
 from sentry import features, projectoptions
 from sentry.eventstream.types import EventStreamEventType
 from sentry.exceptions import PluginError
+from sentry.features.rollout import in_rollout_group
 from sentry.issues.grouptype import GroupCategory
 from sentry.issues.issue_occurrence import IssueOccurrence
 from sentry.killswitches import killswitch_matches_context
@@ -611,7 +612,9 @@ def get_event_raise_exception() -> Event:
         # Simplified post processing for transaction events.
         # This should eventually be completely removed and transactions
         # will not go through any post processing.
-        if is_transaction_event:
+        if is_transaction_event and not in_rollout_group(
+            "transactions.do_post_process_in_save", event.project_id
+        ):
             record_transaction_name_for_clustering(event.project, event.data)
             with sentry_sdk.start_span(op="tasks.post_process_group.transaction_processed_signal"):
                 transaction_processed.send_robust(

tests/sentry/tasks/test_post_process.py

@@ -2734,6 +2734,41 @@ def test_process_transaction_event_clusterer(
             mock.call(ClustererNamespace.TRANSACTIONS, self.project, "foo")
         ]
 
+    @patch("sentry.ingest.transaction_clusterer.datasource.redis._record_sample")
+    @override_options({"transactions.do_post_process_in_save": 1.0})
+    def test_process_transaction_event_clusterer_flag_on(
+        self,
+        mock_store_transaction_name,
+    ):
+        min_ago = before_now(minutes=1)
+        event = process_event(
+            data={
+                "project": self.project.id,
+                "event_id": "b" * 32,
+                "transaction": "foo",
+                "start_timestamp": str(min_ago),
+                "timestamp": str(min_ago),
+                "type": "transaction",
+                "transaction_info": {
+                    "source": "url",
+                },
+                "contexts": {"trace": {"trace_id": "b" * 32, "span_id": "c" * 16, "op": ""}},
+            },
+            group_id=0,
+        )
+        cache_key = write_event_to_cache(event)
+        post_process_group(
+            is_new=False,
+            is_regression=False,
+            is_new_group_environment=False,
+            cache_key=cache_key,
+            group_id=None,
+            project_id=self.project.id,
+            eventstream_type=EventStreamEventType.Transaction,
+        )
+
+        assert mock_store_transaction_name.mock_calls == []
+
 
 class PostProcessGroupGenericTest(
     TestCase,