python web服务问题排查

一、排查uwsgi web服务异常的一般步骤

top命令 简单查看 cpu 内存
查看监控面板（查看组件是否异常 连接数 内存 硬盘）
uwsgitop 拿到busy的pid 使用py-spy查看
py-spy 查看调用栈
elk查看日志 最后根据调用栈和日志分析问题

二、cpu负载异常排查

查看当前进程负载信息
py-spy top --pid 7670 或者
py-spy top-python myprogram.py

生成火焰图分析
py-spy record -o profile.svg --pid 7670 或者
py-spy record -o profile.svg-python myprogram.py

三、内存泄露排查

last_snapshot = None
start_snapshot = None

import gc
import tracemalloc


class BeginShow(APIView):
    """
    刚启动程序时执行，记录下创世内存快照
    """
    authentication_classes = ()
    permission_classes = ()
    def get(self, request):
        tracemalloc.start()
        
        global last_snapshot
        global start_snapshot
        last_snapshot = None
        
        start_snapshot = tracemalloc.take_snapshot()
        return Response({"start_snapshot":"ok"})


class ShowMem(APIView):
    authentication_classes = ()
    permission_classes = ()
    def get(self, request):
        """
        用当前快照分别跟上次快照，创世快照对比，找出没释放的内存差值
        """
    
    
        dump_string = ""
        try:
            # gc.collect()  # 在快照之前手动回收
            snapshot = tracemalloc.take_snapshot()
            top_stats = snapshot.statistics('lineno')
            
            for stat in top_stats[:50]:
                dump_string += "%s\n" % stat
            
            global last_snapshot
            global start_snapshot
            if last_snapshot:
                
                dump_string += "\ncompare to last:\n"
                top_stats = snapshot.compare_to(last_snapshot, 'lineno')
                for stat in top_stats[:50]:
                    dump_string += "%s\n" % stat
            
            if start_snapshot:
                
                dump_string += "\ncompare to start:\n"
                top_stats = snapshot.compare_to(start_snapshot, 'lineno')
                for stat in top_stats[:50]:
                    dump_string += "%s\n" % stat
            
            last_snapshot = snapshot
        
        
        except Exception as e:
            dump_string += "%s\n" % str(e)
        return Response({"dump_string": dump_string})

先调用 BeginShow
后面再调用 ShowMem 查看内存差值