Collect_events Error: deadlock detected

> [!NOTE]
> Migrated from [augurlabs/augur#3170](https://github.com/augurlabs/augur/issues/3170)
> Originally opened by `@cdolfi` on 2025-06-05

---

We are seeing over 100 of these

```
Traceback (most recent call last):
File "/opt/venv/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 1938, in _exec_single_context
self.dialect.do_executemany(
File "/opt/venv/lib/python3.9/site-packages/sqlalchemy/dialects/postgresql/psycopg2.py", line 794, in do_executemany
cursor.executemany(statement, parameters)
psycopg2.errors.DeadlockDetected: deadlock detected
DETAIL: Process 1969098 waits for ShareLock on transaction 145676170; blocked by process 1969078.
Process 1969078 waits for ShareLock on transaction 145676175; blocked by process 1969098.
HINT: See server log for query details.
CONTEXT: while locking tuple (2423229,6) in relation "contributors"
SQL statement "SELECT 1 FROM ONLY "augur_data"."contributors" x WHERE "cntrb_id" OPERATOR(pg_catalog.=) $1 FOR KEY SHARE OF x"

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
File "/opt/venv/lib/python3.9/site-packages/celery/app/trace.py", line 451, in trace_task
R = retval = fun(*args, **kwargs)
File "/opt/venv/lib/python3.9/site-packages/celery/app/trace.py", line 734, in __protected_call__
return self.run(*args, **kwargs)
File "/augur/augur/tasks/github/events.py", line 46, in collect_events
collection_strategy.collect(repo_git, key_auth, core_data_last_collected)
File "/augur/augur/tasks/github/events.py", line 124, in collect
self._process_events(events, repo_id)
File "/augur/augur/tasks/github/events.py", line 167, in _process_events
update_issue_closed_cntrbs_by_repo_id(repo_id)
File "/augur/augur/application/db/lib.py", line 567, in update_issue_closed_cntrbs_by_repo_id
connection.execute(update_stmt, update_data)
File "/opt/venv/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 1416, in execute
return meth(
File "/opt/venv/lib/python3.9/site-packages/sqlalchemy/sql/elements.py", line 516, in _execute_on_connection
return connection._execute_clauseelement(
File "/opt/venv/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 1639, in _execute_clauseelement
ret = self._execute_context(
File "/opt/venv/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 1848, in _execute_context
return self._exec_single_context(
File "/opt/venv/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 1988, in _exec_single_context
self._handle_dbapi_exception(
File "/opt/venv/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 2343, in _handle_dbapi_exception
raise sqlalchemy_exception.with_traceback(exc_info[2]) from e
File "/opt/venv/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 1938, in _exec_single_context
self.dialect.do_executemany(
File "/opt/venv/lib/python3.9/site-packages/sqlalchemy/dialects/postgresql/psycopg2.py", line 794, in do_executemany
cursor.executemany(statement, parameters)
sqlalchemy.exc.OperationalError: (psycopg2.errors.DeadlockDetected) deadlock detected
DETAIL: Process 1969098 waits for ShareLock on transaction 145676170; blocked by process 1969078.
Process 1969078 waits for ShareLock on transaction 145676175; blocked by process 1969098.
HINT: See server log for query details.
CONTEXT: while locking tuple (2423229,6) in relation "contributors"
SQL statement "SELECT 1 FROM ONLY "augur_data"."contributors" x WHERE "cntrb_id" OPERATOR(pg_catalog.=) $1 FOR KEY SHARE OF x"

[SQL:
UPDATE issues
SET cntrb_id = %(cntrb_id)s
WHERE issue_id = %(issue_id)s
AND repo_id = %(repo_id)s
]
[parameters: [{'cntrb_id': UUID('0105275d-6400-0000-0000-000000000000'), 'issue_id': 24652500, 'repo_id': 64768}, {'cntrb_id': UUID('0102bfea-9500-0000-0000-000000000000'), 'issue_id': 24652501, 'repo_id': 64768}, {'cntrb_id': UUID('01017e42-7700-0000-0000-000000000000'), 'issue_id': 24652502, 'repo_id': 64768}, {'cntrb_id': UUID('01017e42-7700-0000-0000-000000000000'), 'issue_id': 24652503, 'repo_id': 64768}, {'cntrb_id': UUID('0101e0c8-0a00-0000-0000-000000000000'), 'issue_id': 24652505, 'repo_id': 64768}, {'cntrb_id': UUID('01017e42-7700-0000-0000-000000000000'), 'issue_id': 24652507, 'repo_id': 64768}, {'cntrb_id': UUID('0105275d-6400-0000-0000-000000000000'), 'issue_id': 24652508, 'repo_id': 64768}, {'cntrb_id': UUID('01017e42-7700-0000-0000-000000000000'), 'issue_id': 24652509, 'repo_id': 64768} ... displaying 10 of 685 total bound parameter sets ... {'cntrb_id': UUID('01000488-dd00-0000-0000-000000000000'), 'issue_id': 228519090, 'repo_id': 64768}, {'cntrb_id': UUID('01000488-dd00-0000-0000-000000000000'), 'issue_id': 230637437, 'repo_id': 64768}]]
(Background on this error at: https://sqlalche.me/e/20/e3q8)
```