FIX: Reduce symbol subscription batch size

Author: nmacholl

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Changelog
 
+## 0.22.2 - TBD
+
+#### Bug fixes
+- Fixed issue where a large unreadable symbol subscription message could be sent
+
 ## 0.22.1 - 2023-10-24
 
 #### Bug fixes

databento/live/protocol.py

@@ -5,6 +5,7 @@
 from collections.abc import Iterable
 from functools import singledispatchmethod
 from numbers import Number
+from typing import Final
 
 import databento_dbn
 from databento_dbn import Schema
@@ -30,7 +31,8 @@
 from databento.live.gateway import SubscriptionRequest
 
 
-RECV_BUFFER_SIZE: int = 64 * 2**10  # 64kb
+RECV_BUFFER_SIZE: Final = 64 * 2**10  # 64kb
+SYMBOL_LIST_BATCH_SIZE: Final = 64
 
 logger = logging.getLogger(__name__)
 
@@ -278,7 +280,7 @@ def subscribe(
         stype_in_valid = validate_enum(stype_in, SType, "stype_in")
         symbols_list = optional_symbols_list_to_list(symbols, stype_in_valid)
 
-        for batch in chunk(symbols_list, 128):
+        for batch in chunk(symbols_list, SYMBOL_LIST_BATCH_SIZE):
             batch_str = ",".join(batch)
             message = SubscriptionRequest(
                 schema=validate_enum(schema, Schema, "schema"),

tests/test_live_client.py

@@ -399,14 +399,24 @@ async def test_live_subscribe_large_symbol_list(
     first_message = mock_live_server.get_message_of_type(
         gateway.SubscriptionRequest,
         timeout=1,
-    )
+    ).symbols.split(",")
 
     second_message = mock_live_server.get_message_of_type(
         gateway.SubscriptionRequest,
         timeout=1,
-    )
+    ).symbols.split(",")
+
+    third_message = mock_live_server.get_message_of_type(
+        gateway.SubscriptionRequest,
+        timeout=1,
+    ).symbols.split(",")
+
+    fourth_message = mock_live_server.get_message_of_type(
+        gateway.SubscriptionRequest,
+        timeout=1,
+    ).symbols.split(",")
 
-    reconstructed = first_message.symbols.split(",") + second_message.symbols.split(",")
+    reconstructed = first_message + second_message + third_message + fourth_message
     assert reconstructed == large_symbol_list