uwsgi网络积压数扩增

前言

生产环境遇到了并发产生的错误：服务在被调用的过程中超时。

排查后原因是flask+uwsgi部署方案中的请求积压队列大小默认只有100，所以如果短时间服务收到大量的请求并没来得及处理，积压的队列如果超过了100，后续的请求系统就不再响应了。

Note that a “listen backlog” of 100 connections doesn’t mean that your server can only handle 100 simultaneous (or total) connections - this is instead dependent on the number of configured processes or threads. The listen backlog is a socket setting telling the kernel how to limit the number of outstanding (as yet unaccapted) connections in the listen queue of a listening socket. If the number of pending connections exceeds the specified size, new ones are automatically rejected. A functioning server regularly servicing its connections should not require a large backlog size.

所以可以从两个角度来优化:

(1) 增加积压队列的大小，从100调整到1000

(2) 增加flask的处理速度，调高进程的数量

处理方案

1.修改uwsgi的文件

[uwsgi]
module = main
callable = app
processes = 8
master = 1
listen = 10240

调整processes的大小为8，listen的大小为10240

2.修改主机的网络连接限制

sysctl -w net.core.somaxconn=10240

对于docker容器部署，则是设置容器中的内核参数

对于docker-compose:

https://www.runoob.com/docker/docker-compose.html

sysctls:
      - net.core.somaxconn=10240

对于k8s:

https://kubernetes.io/zh/docs/tasks/administer-cluster/sysctl-cluster/

apiVersion: v1
kind: Pod
metadata:
  name: sysctl-example
spec:
  securityContext:
    sysctls:
    - name: kernel.shm_rmid_forced
      value: "0"
    - name: net.core.somaxconn
      value: "1024"
    - name: kernel.msgmax
      value: "65536"
  ...