我通过由Supervisor管理的uWSGI运行Flask应用程序（并且网络服务器正在使用Nginx）。
整个设置似乎完美无缺，但是，我注意到每天或两天，我的烧瓶应用程序开始抛出500个错误（这意味着有一个Sqlalchemy db.commit（）错误）我无法恢复直到我进入并重新加载uwsgi，之后，一切都完美无缺。为了重新加载，我通常会杀死uwsgi进程，并且主管将它们重新带回来并且它很好。一旦我通过触摸wsgi文件就可以让它工作。
同样奇怪的是，每当我使用processes = 1运行supervisor时，它会自动加载两个uwsgi实例。第一个PID是由主管操作记录的PID，另一个不在任何地方注册。然而，无论如何，杀死第二个进程 - 它总会回来。
以下是我的uwsgi启动命令由主管运行
[program:{{ app_name }}]
command=/usr/local/bin/uwsgi
--socket=/tmp/{{ app_name }}.sock
--logto={{ log_dir }}/application.log
--home={{ site_dir }}/env
--pythonpath={{ site_dir }}
--virtualenv={{ env_path }}
--wsgi-file={{ webapps_dir }}/manage.py
--callable={{ wsgi_callable }}
--max-requests=1000
--master
--processes=1
--uid={{ deployment_user }}
--gid=www-data
--chmod-socket=664
--chown-socket={{ deployment_user }}:www-data
directory={{ webapps_dir }}
autostart=true
autorestart=true
编辑：以下是从服务器吐出的错误。
2015-03-19 15:03:38,389 ERROR: Exception on /api/v1/account/login [POST] [in /var/www/website.com/env/local/lib/python2.7/site-packages/flask/app.py:1423]
Traceback (most recent call last):
File "/var/www/website.com/env/local/lib/python2.7/site-packages/flask/app.py", line 1817, in wsgi_app
response = self.full_dispatch_request()
File "/var/www/website.com/env/local/lib/python2.7/site-packages/flask/app.py", line 1477, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/flask_cors.py", line 272, in wrapped_function
return cors_after_request(app.make_response(f(*args, **kwargs)))
File "/var/www/website.com/env/local/lib/python2.7/site-packages/flask/app.py", line 1381, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/flask/app.py", line 1475, in full_dispatch_request
rv = self.dispatch_request()
File "/var/www/website.com/env/local/lib/python2.7/site-packages/flask/app.py", line 1461, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/flask_classy.py", line 200, in proxy
response = view(**request.view_args)
File "./webportal/account/api.py", line 34, in login_user
user = auth.authenticate(username=email, password=password)
File "/var/www/website.com/server/webportal/auth.py", line 23, in authenticate
user = User.query.filter_by(email=username).first()
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2367, in first
ret = list(self[0:1])
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2228, in __getitem__
return list(res)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2438, in __iter__
return self._execute_and_instances(context)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2453, in _execute_and_instances
result = conn.execute(querycontext.statement, self._params)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 729, in execute
return meth(self, multiparams, params)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/sql/elements.py", line 322, in _execute_on_connection
return connection._execute_clauseelement(self, multiparams, params)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 826, in _execute_clauseelement
compiled_sql, distilled_params
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 958, in _execute_context
context)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1159, in _handle_dbapi_exception
exc_info
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/util/compat.py", line 199, in raise_from_cause
reraise(type(exception), exception, tb=exc_tb)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 951, in _execute_context
context)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/engine/default.py", line 436, in do_execute
cursor.execute(statement, parameters)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/MySQLdb/cursors.py", line 205, in execute
self.errorhandler(self, exc, value)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/MySQLdb/connections.py", line 36, in defaulterrorhandler
raise errorclass, errorvalue
OperationalError: (OperationalError) (2006, 'MySQL server has gone away') 'SELECT `Users`.id AS `Users_id`, `Users`.email AS `Users_email`, `Users`.password AS `Users_password`, `Users`.`emailConfirmed` AS `Users_emailConfirmed`, `Users`.`createdAtUtc` AS `Users_createdAtUtc`, `Users`.`updatedAtUtc` AS `Users_updatedAtUtc`, `Users`.`roleId` AS `Users_roleId` \nFROM `Users` \nWHERE `Users`.email = %s \n LIMIT %s' ('user@website.demo', 1)
2015-03-19 15:06:22,089 ERROR: Exception on /api/v1/account/login [POST] [in /var/www/website.com/env/local/lib/python2.7/site-packages/flask/app.py:1423]
Traceback (most recent call last):
File "/var/www/website.com/env/local/lib/python2.7/site-packages/flask/app.py", line 1817, in wsgi_app
response = self.full_dispatch_request()
File "/var/www/website.com/env/local/lib/python2.7/site-packages/flask/app.py", line 1477, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/flask_cors.py", line 272, in wrapped_function
return cors_after_request(app.make_response(f(*args, **kwargs)))
File "/var/www/website.com/env/local/lib/python2.7/site-packages/flask/app.py", line 1381, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/flask/app.py", line 1475, in full_dispatch_request
rv = self.dispatch_request()
File "/var/www/website.com/env/local/lib/python2.7/site-packages/flask/app.py", line 1461, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/flask_classy.py", line 200, in proxy
response = view(**request.view_args)
File "./webportal/account/api.py", line 34, in login_user
user = auth.authenticate(username=email, password=password)
File "/var/www/website.com/server/webportal/auth.py", line 23, in authenticate
user = User.query.filter_by(email=username).first()
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2367, in first
ret = list(self[0:1])
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2228, in __getitem__
return list(res)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2438, in __iter__
return self._execute_and_instances(context)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2453, in _execute_and_instances
result = conn.execute(querycontext.statement, self._params)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 729, in execute
return meth(self, multiparams, params)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/sql/elements.py", line 322, in _execute_on_connection
return connection._execute_clauseelement(self, multiparams, params)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 826, in _execute_clauseelement
compiled_sql, distilled_params
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 893, in _execute_context
None, None)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1159, in _handle_dbapi_exception
exc_info
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/util/compat.py", line 199, in raise_from_cause
reraise(type(exception), exception, tb=exc_tb)
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 887, in _execute_context
conn = self._revalidate_connection()
File "/var/www/website.com/env/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 242, in _revalidate_connection
"Can't reconnect until invalid "
StatementError: Can't reconnect until invalid transaction is rolled back (original cause: InvalidRequestError: Can't reconnect until invalid transaction is rolled back) u'SELECT `Users`.id AS `Users_id`, `Users`.email AS `Users_email`, `Users`.password AS `Users_password`, `Users`.`emailConfirmed` AS `Users_emailConfirmed`, `Users`.`createdAtUtc` AS `Users_createdAtUtc`, `Users`.`updatedAtUtc` AS `Users_updatedAtUtc`, `Users`.`roleId` AS `Users_roleId` \nFROM `Users` \nWHERE `Users`.email = %s \n LIMIT %s' [immutabledict({})]
根据https://dev.mysql.com/doc/refman/5.0/en/gone-away.html，MySQL会在8小时后关闭连接......一旦发生这种情况，应用就会处于某种状态。