在参数优化，老是出现下面内容
Exception in thread Thread-4:
Traceback (most recent call last):
File "D:\vnstudio D\lib\threading.py", line 917, in _bootstrap_inner
self.run()
File "D:\vnstudio D\lib\threading.py", line 865, in run
self._target(*self._args, **self._kwargs)
File "D:\vnstudio D\lib\site-packages\vnpy\app\cta_backtester\engine.py", line 295, in run_optimization
output=False
File "D:\vnstudio D\lib\site-packages\vnpy\app\cta_strategy\backtesting.py", line 555, in run_optimization
settings = optimization_setting.generate_setting()
File "D:\vnstudio D\lib\site-packages\vnpy\app\cta_strategy\backtesting.py", line 89, in generate_setting
settings.append(setting)
MemoryError
