def get_instance(cls, max_workers: int = 16, reset_threshold: int = 100000) -> 'GlobalProcessPool':
        """Get or create the singleton instance of GlobalProcessPool."""
        if cls._instance is None:
            with cls._lock:
                if cls._instance is None:
                    cls._instance = cls(max_workers=max_workers, reset_threshold=reset_threshold)
        return cls._instance
Get or create the singleton instance of GlobalProcessPool.
verl/utils/reward_score/hf_math_verify.py