定位python内存泄漏问题及解决_开发_开发者

背景

上周使用我的python web框架开发的第二个项目上线了，但是没运行几天机器内存就报警了，8G内存使用了7G，怀疑有内存泄漏，这个项目提供的功能就是一堆机器学习模型，对历史数据进行训练，挑选出最优的5个模型，用作未来数据的预测，所以整个项目有着数据量大，运行时间长的特点，就是把策略的离线工作搬到了线上。

定位内存泄漏

第一步：确定是否有内存泄漏

上pympler检查是否有内存泄漏,程序入口处初始化该工具

from pympler import tracker,summary,muppy
memory_tracker = tracker.SummaryTracker()

接口返回处打印内存差异，观察内存是否有泄漏

memory_tracker.print_diff() # 本次内存和上次内存块的差异

我们用的sanic，所以直接在main.py文件添加如下代码:

 from pympler import tracker,summary,muppy
 memory_tracker = tracker.SummaryTracker()

 @app.middleware('request')
 async def set_request_id(request):
     log_id = request.headers.get('log-id')
     threading.currentThread().logid = log_id
     gc.collect()
     memory_tracker.print_diff()

然后我们访问接口，多触发几次，不用看前两次，等输出稳定后，如果有内存泄漏是如下输出：

定位python内存泄漏问题及解决

上图显示每次都有4类泄漏对象，一共泄漏约60K的内存

如果没有内存泄漏，没有数据输出

定位python内存泄漏问题及解决

第二步：确定内心泄漏的代码块

我们确定程序有内存泄漏后，就想办法定位到代码块，就是我们自己写的代码，通过一步一步debug，注释，return，continue等方式定位到造成泄漏的代码块，下面的代码块就是遍历所有模型，然后挨个执行训练方法，因为有20多个模型，我不能挨个注释每次对象来定位，卡在这里了。

定位python内存泄漏问题及解决

第三步：确定泄漏点

上tracemalajjoqrTloc定位泄漏点，python3.7.3自带，在main.py中添加如下代码：

tracemalloc.start(25)
snapshot = tracemalloc.take_snapshot()
@app.middleware('response')
async def print_on_response(request, response):
    global snapshot
    gc.collect()
    snapshot1 = tracemalloc.take_snapshot()
    top_stats = snapshot1.compare_to(snapshot, 'lineno')
    print("[ Top 10 differences ]")
 	for stat in top_stats[:10]:
    	 if stat.size_diff < 0:
			continue
 		 print(stat)
 	snapshot = tracemalloc.take_snapshot()

继续访问接口，多访问几次，输出如下，直接定位到具体泄漏的代码位置

定位python内存泄漏问题及解决

图中所有的泄漏点都定位到pandas库，但是我用这些文件搜索内存泄漏，都没有搜到相关内存泄漏的问题，所以得寻找谁调用这些地方，以

/home/doctorq/.local/share/virtualenvs/scscore-K9x97I77/lib/python3.7/site-packages/pandas/core/window.py:859

www.devze.com

为例，我们要找到我们写的代码哪里调用触发泄漏点

第四步：打印调用链

看了tracemalloc文档也没找到打印调用链的方法，后来灵机一动直接在这个文件加了下面代码：

raise Exception("doctorq")

然后在接口里catch异常，添加logging.exception(e)，然后触发接口，打印堆栈信息：

ERROR:root:doctorq
Traceback (most recent call last):
File "/home/doctorq/python-dev/scscore/src/forecasting/forecast.py", line 83, in update_method
n_fraction=n_fraction)
File "/home/doctorq/python-dev/scscore/src/forecasting/trainer.py", line 113, in training
n_fraction=n_fraction)
File "/home/doctorq/python-dev/scscore/src/forecasting/trainer.py", line 205, in train_MAChine_learning_model
is_train=True).dropna()
File &qu编程ot;/home/doctorq/python-dev/scscore/src/feature_engineering/features.py", line 34, in get_feature
history_same_periods=history_same_periods, zero_replace=zero_replace)
File "/home/doctorq/python-dev/scscore/src/feature_engineering/sale_relate_feature.py", line 65, in get_feature
store_and_sku=store_and_sku)
File "/home/doctorq/python-dev/scscore/src/feature_engineering/sale_relate_feature.py", line 85, in get_rolling_feature
rolling_result = self.get_rolling_result(window, rolling_obj, rolling_types)
File "/home/doctorq/python-dev/scscore/src/feature_engineering/sale_relate_feature.py", line 169, in get_rolling_result
rolling_result = self.rolling__(rolling_obj, rolling_type)
File "/home/doctorq/python-dev/scscore/src/feature_engineering/sale_relate_feature.py", line 190, in rolling__
return rolling_obj.min()
File "/home/doctorq/.local/share/vihttp://www.devze.comrtualenvs/scscore-K9x97I77/lib/python3.7/site-packages/pandas/core/window.py", line 1723, in min
return super(Rolling, self).min(*args, **kwargs)
File "/home/doctorq/.local/share/virtualenvs/scscore-K9x97I77/lib/python3.7/site-packages/pandas/core/window.py", line 1069, in min
return self._apply('roll_min', 'min', **kwargs)
File "/home/doctorq/.local/share/virtualenvs/scscore-K9x97I77/lib/python3.7/site-packages/pandas/core/window.py", line 879, in _apply
result = np.apply_along_axis(calc, self.axis, values)
File "/home/doctorq/.local/share/virtualenvs/scscore-K9x97I77/lib/python3.7/site-packages/numpy/lib/shape_base.py", line 380, in apply_along_axis
res = asanyarray(func1d(inarr_view[ind0], *args, **kwargs))
File "/home/doctorq/.local/share/virtualenvs/scscore-K9x97I77/lib/python3.7/site-packages/pandas/core/window.py", line 875, in calc
closed=self.closed)
File "/home/doctorq/.local/share/virtualenvs/scscore-K9x97I77/lib/python3.7/site-packages/pandas/core/window.py", line 858, in func
&ajjoqrTnbsp; raise Exception("doctorq")
Exception: doctorq