Don't use database in app.ready

safe_transaction_service/contracts/tx_decoder.py

@@ -2,6 +2,7 @@
 import operator
 from functools import cache, cached_property
 from logging import getLogger
+from threading import Lock
 from typing import (
     Any,
     Dict,
@@ -118,6 +119,9 @@ class MultisendDecoded(TypedDict):
     data_decoded: Optional[DataDecoded]
 
 
+mutex = Lock()
+
+
 @cache
 def get_db_tx_decoder() -> "DbTxDecoder":
     """
@@ -127,16 +131,19 @@ def get_db_tx_decoder() -> "DbTxDecoder":
         the ``DbTxDecoder`` multiple times, and depending on the number of Contracts in the database it could
         take a lot.
     """
-
-    def _get_db_tx_decoder() -> "DbTxDecoder":
-        return DbTxDecoder()
-
-    if running_on_gevent():
-        # It's a very intensive CPU task, so to prevent blocking
-        # http://www.gevent.org/api/gevent.threadpool.html
-        pool = gevent.get_hub().threadpool
-        return pool.spawn(_get_db_tx_decoder).get()
-    return _get_db_tx_decoder()
+    with mutex:
+        if is_db_tx_decoder_loaded():
+            return get_db_tx_decoder()
+
+        def _get_db_tx_decoder() -> "DbTxDecoder":
+            return DbTxDecoder()
+
+        if running_on_gevent():
+            # It's a very intensive CPU task, so to prevent blocking
+            # http://www.gevent.org/api/gevent.threadpool.html
+            pool = gevent.get_hub().threadpool
+            return pool.spawn(_get_db_tx_decoder).get()
+        return _get_db_tx_decoder()
 
 
 def is_db_tx_decoder_loaded() -> bool:

safe_transaction_service/history/apps.py

@@ -1,5 +1,3 @@
-import sys
-
 from django.apps import AppConfig
 
 
@@ -9,14 +7,3 @@ class HistoryConfig(AppConfig):
 
     def ready(self):
         from . import signals  # noqa
-
-        for argument in sys.argv:
-            if "gunicorn" in argument:  # pragma: no cover
-                # Just run this on production
-                # TODO Find a better way
-                from safe_transaction_service.contracts.tx_decoder import (
-                    get_db_tx_decoder,
-                )
-
-                get_db_tx_decoder()  # Build tx decoder cache
-                break