[core] restrict logging of quant config based on the header size. (#14262)

restrict logging of quant config based on the header size.

Author: sayakpaul

src/diffusers/models/modeling_utils.py

@@ -98,6 +98,11 @@ def __exit__(self, *args, **kwargs):
 
 _REGEX_SHARD = re.compile(r"(.*?)-\d{5}-of-\d{5}")
 
+# The `user_agent` dict is flattened into a single `user-agent` HTTP header. Serializing an
+# unbounded `quantization_config` into it can exceed server header size limits, so we only
+# attach the serialized config for telemetry when it stays under this many characters.
+_MAX_QUANT_CONFIG_USER_AGENT_CHARS = 2048
+
 TORCH_INIT_FUNCTIONS = {
     "uniform_": nn.init.uniform_,
     "normal_": nn.init.normal_,
@@ -1162,7 +1167,11 @@ def from_pretrained(cls, pretrained_model_name_or_path: str | os.PathLike | None
 
             # In order to ensure popular quantization methods are supported. Can be disabled with `disable_telemetry`
             user_agent["quant"] = hf_quantizer.quantization_config.quant_method.value
-            user_agent["quant_config"] = json.dumps(hf_quantizer.quantization_config.to_dict(), sort_keys=True)
+            # Attach the full serialized config for telemetry, but skip it when it is large enough to
+            # risk exceeding HTTP header size limits (see `_MAX_QUANT_CONFIG_USER_AGENT_CHARS`).
+            serialized_quant_config = json.dumps(hf_quantizer.quantization_config.to_dict(), sort_keys=True)
+            if len(serialized_quant_config) <= _MAX_QUANT_CONFIG_USER_AGENT_CHARS:
+                user_agent["quant_config"] = serialized_quant_config
 
             # Force-set to `True` for more mem efficiency
             if low_cpu_mem_usage is None: