feat: CONTRACT_THREADS env (#786)

* feat: CONTRACT_THREADS env

* chore: `black .`

* Update contracts.py

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

y/ENVIRONMENT_VARIABLES.py

@@ -10,6 +10,15 @@
 )
 """TTL for contract cache, defaults to :obj:`CACHE_TTL` if not set"""
 
+CONTRACT_THREADS = _envs.create_env(
+    "CONTRACT_THREADS",
+    PruningThreadPoolExecutor,
+    default=10,
+    string_converter=int,
+    verbose=False,
+)
+"""The number of threads to use to fetch contract abis"""
+
 GETLOGS_BATCH_SIZE = _envs.create_env("GETLOGS_BATCH_SIZE", int, default=0)
 """Batch size for getlogs operations, 0 will use default as determined by your provider."""
 

y/contracts.py

@@ -49,8 +49,6 @@
 
 logger = logging.getLogger(__name__)
 
-contract_threads = a_sync.PruningThreadPoolExecutor(16)
-
 _brownie_deployments_db_lock = threading.Lock()
 
 # These tokens have trouble when resolving the implementation via the chain.
@@ -473,7 +471,7 @@ async def _coroutine(
         Returns:
             A Contract instance for the given address.
         """
-        contract = await contract_threads.run(
+        contract = await ENVS.CONTRACT_THREADS.run(
             cls, address, require_success=require_success
         )