always finalize the serialized transaction so that it doesn't leak ou… (#2843)

* always finalize the serialized transaction so that it doesn't leak outside the function

* re-raise the exception and log it

backend/danswer/background/indexing/run_indexing.py

@@ -387,6 +387,7 @@ def _prepare_index_attempt(
     # after the next commit:
     # https://docs.sqlalchemy.org/en/20/orm/session_transaction.html#setting-isolation-for-individual-transactions
     db_session.connection(execution_options={"isolation_level": "SERIALIZABLE"})  # type: ignore
+    try:
         if tenant_id is not None:
             # Explicitly set the search path for the given tenant
             db_session.execute(text(f'SET search_path TO "{tenant_id}"'))
@@ -401,7 +402,9 @@ def _prepare_index_attempt(
         )
 
         if attempt is None:
-        raise RuntimeError(f"Unable to find IndexAttempt for ID '{index_attempt_id}'")
+            raise RuntimeError(
+                f"Unable to find IndexAttempt for ID '{index_attempt_id}'"
+            )
 
         if attempt.status != IndexingStatus.NOT_STARTED:
             raise RuntimeError(
@@ -409,9 +412,15 @@ def _prepare_index_attempt(
                 f"Current status is '{attempt.status}'."
             )
 
-    # only commit once, to make sure this all happens in a single transaction
         mark_attempt_in_progress(attempt, db_session)
 
+        # only commit once, to make sure this all happens in a single transaction
+        db_session.commit()
+    except Exception:
+        db_session.rollback()
+        logger.exception("_prepare_index_attempt exceptioned.")
+        raise
+
     return attempt