运行gunicorn后显示如下错误：
root@iZ2ze2gihbn4ot85zlcdxdZ:~/myproject# gunicorn -w 4 -b 0.0.0.0:5000 myapp:app
[2018-03-16 15:48:33 +0800] [9555] [INFO] Starting gunicorn 19.7.1
[2018-03-16 15:48:33 +0800] [9555] [ERROR] Connection in use: ('0.0.0.0', 5000)
[2018-03-16 15:48:33 +0800] [9555] [ERROR] Retrying in 1 second.
[2018-03-16 15:48:34 +0800] [9555] [ERROR] Connection in use: ('0.0.0.0', 5000)
[2018-03-16 15:48:34 +0800] [9555] [ERROR] Retrying in 1 second.
[2018-03-16 15:48:35 +0800] [9555] [ERROR] Connection in use: ('0.0.0.0', 5000)
[2018-03-16 15:48:35 +0800] [9555] [ERROR] Retrying in 1 second.
[2018-03-16 15:48:36 +0800] [9555] [ERROR] Connection in use: ('0.0.0.0', 5000)
[2018-03-16 15:48:36 +0800] [9555] [ERROR] Retrying in 1 second.
[2018-03-16 15:48:37 +0800] [9555] [ERROR] Connection in use: ('0.0.0.0', 5000)
[2018-03-16 15:48:37 +0800] [9555] [ERROR] Retrying in 1 second.
[2018-03-16 15:48:38 +0800] [9555] [ERROR] Can't connect to ('0.0.0.0', 5000)
显示正在运行的gunicorn进程，发现没有已经运行zai 0.0.0.0：5000的进程：
root@iZ2ze2gihbn4ot85zlcdxdZ:~/myproject# pstree -ap|grep gunicorn | |-grep,9539 --color=auto gunicorn
这时查看服务器（主机）运行的全部进程：
root@iZ2ze2gihbn4ot85zlcdxdZ:~/myproject# ps -a PID TTY TIME CMD 9446 pts/0 00:00:00 su 9447 pts/0 00:00:00 bash 9488 pts/0 00:00:00 sudo 9489 pts/0 00:00:00 bash 9514 pts/0 00:00:00 python3 9516 pts/0 00:00:00 python3 9551 pts/0 00:00:00 ps
这时发现有两个python3的进程，其中有一个是运行的myapp.py文件的进程，而gunicorn要运行的就是该文件，因此产生冲突。
删掉进程：
root@iZ2ze2gihbn4ot85zlcdxdZ:~/myproject# kill -9 9516 [2]+ Killed python3 myapp.py
这时再运行gunicorn就好了：
root@iZ2ze2gihbn4ot85zlcdxdZ:~/myproject# gunicorn -w 4 -b 0.0.0.0:5000 myapp:app [2018-03-16 15:49:41 +0800] [9558] [INFO] Starting gunicorn 19.7.1 [2018-03-16 15:49:41 +0800] [9558] [INFO] Listening at: http://0.0.0.0:5000 (9558) [2018-03-16 15:49:41 +0800] [9558] [INFO] Using worker: sync [2018-03-16 15:49:41 +0800] [9561] [INFO] Booting worker with pid: 9561 [2018-03-16 15:49:41 +0800] [9563] [INFO] Booting worker with pid: 9563 [2018-03-16 15:49:41 +0800] [9564] [INFO] Booting worker with pid: 9564 [2018-03-16 15:49:42 +0800] [9565] [INFO] Booting worker with pid: 9565