一个奇怪的问题，在uwsgi配置使用socket与Nginx通信，且在Django/Flask等使用了多进程时，请求会卡住，具体配置如下：
UWSGI配置：
[uwsgi] chdir = /home/pi/uwsgiapp wsgi-file = app.py callable=app master = true processes = 2 vhost = true socket=127.0.0.1:5050 chmod-socket = 664 http-keepalive=3000 stats=127.0.0.1:1717
Nginx配置：
user www-data; worker_processes 1; pid /run/nginx.pid; include /etc/nginx/modules-enabled/*.conf; events { worker_connections 768; # multi_accept on; } http { server { listen 80; server_name 127.0.0.1; charset utf-8; client_max_body_size 75M; # adjust to taste location / { include uwsgi_params; uwsgi_pass 127.0.0.1:5050; proxy_buffering off; } } include /etc/nginx/conf.d/*.conf; include /etc/nginx/sites-enabled/*; }
app.py内容
import time from multiprocessing import Process from flask import Flask, jsonify, request app = Flask(__name__) app.config[‘JSON_AS_ASCII‘] = False def hello(): while True: print("ohhhh") time.sleep(5) @app.route(‘/test/‘, methods=[‘GET‘,‘POST‘]) def getProxiesList(): p = Process(target=hello) p.start() return jsonify({‘data‘:‘ok‘})
启动Nginx和uwsgi后，curl访问http://127.0.0.1/test，uwsgi后台可见已返回请求并每隔5秒打印ohhhh，但curl卡住
curl -v http://127.0.0.1/test/ * Expire in 0 ms for 6 (transfer 0x11fb7c0) * Trying 127.0.0.1... * TCP_NODELAY set * Expire in 200 ms for 4 (transfer 0x11fb7c0) * Connected to 127.0.0.1 (127.0.0.1) port 80 (#0) > GET /test/ HTTP/1.1 > Host: 127.0.0.1 > User-Agent: curl/7.64.0 > Accept: */* >
最终触发Nginx超时：[error] 32702#32702: *11 upstream timed out (110: Connection timed out) while reading upstream, client: 127.0.0.1, server: 127.0.0.1, request: "GET /test HTTP/1.1", upstream: "uwsgi://127.0.0.1:5050", host: "127.0.0.1"
更改uwsgi中process，threads，lazy-apps，close-on-exec均无效。
但以下两种情况多进程可以正常运行
1. uwsgi配置为http服务器，Nginx使用proxy_pass模式转发
2. uwsgi配置enable-threads=true，同时app.py里将多进程替换为多线程模块
目前笔者尚未分析出出现此现象的原因。