Handle non-serializable objects when dumping benchmark results (vllm-project#19114)

Author: huydhn

.pre-commit-config.yaml

@@ -11,6 +11,8 @@ repos:
   hooks:
   - id: yapf
     args: [--in-place, --verbose]
+    # Keep the same list from yapfignore here to avoid yapf failing without any inputs
+    exclude: '(.buildkite|benchmarks|build|examples)/.*'
 - repo: https://github.com/astral-sh/ruff-pre-commit
   rev: v0.11.7
   hooks:

benchmarks/benchmark_utils.py

@@ -66,4 +66,9 @@ def iterencode(self, o: Any, *args, **kwargs) -> Any:
 
 def write_to_json(filename: str, records: list) -> None:
     with open(filename, "w") as f:
-        json.dump(records, f, cls=InfEncoder)
+        json.dump(
+            records,
+            f,
+            cls=InfEncoder,
+            default=lambda o: f"<{type(o).__name__} object is not JSON serializable>",
+        )