[Fix] Fix eval stage is extremely slow

[xming521]

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[Copilot]

Pull request overview

This PR targets a performance issue where the eval stage is extremely slow due to Python code formatting being applied during config dump operations in the LocalRunner. By setting _format_python_code = False on the task config object before calling dump(), the expensive code formatting step is skipped.

Changes:

• Disables Python code formatting on the task config before dumping it to a temporary file in LocalRunner._launch()

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[Copilot]

The fix to disable Python code formatting during config dump (line 219) is only applied in the _launch method (the non-debug path of LocalRunner), but the same slow behavior can occur in:

1. The debug path of LocalRunner (local.py line 110), which also calls task.cfg.dump(param_file) without the fix.
2. All other runners that call cfg.dump(param_file) without this optimization: slurm.py (line 99), dlc.py (line 127), rjob.py (line 185), volc.py (line 115), slurm_sequential.py (line 182), and local_api.py (line 200).

The fix should be applied consistently to all cfg.dump() call sites across all runners to fully address the performance issue.

[Copilot]

Using object.__setattr__() to set _format_python_code on the mmengine Config object is a fragile approach that bypasses the class's __setattr__ mechanism and relies on the internal implementation of mmengine's Config. If mmengine changes its internal attribute names or layout, this will silently fail to have any effect (without raising an error), causing the performance issue to reappear undetected.

The rest of the codebase (e.g., opencompass/cli/main.py:301 and opencompass/utils/run.py:98) passes format_python_code=False directly to Config.fromfile(). Since the task config is already a Config object at this point, a more robust alternative is to reload it with the correct flag, or to check if mmengine's Config exposes a public setter for format_python_code and use that instead.

Suggested change

	object.__setattr__(task.cfg, "_format_python_code", False)
	# Prefer using a public API to control python code formatting if available
	if hasattr(task.cfg, 'format_python_code'):
	try:
	task.cfg.format_python_code = False
	except Exception:
	# If setting fails, fall back to default behavior
	pass