我有一个django站点，后端使用sqlite，最近我们升级到MySQL，现在收到间歇性错误：
'MySQL服务器已经消失'
启动网站后，它加载正常，点击更改页面通常会在查看1到6页后导致错误。它出现的页面似乎是无关紧要的，同一页面可能第一次加载但第二次抛出错误。
这是我的环境：
我尝试使用本地MySQL服务器而不是谷歌云MySQL，它没有什么区别。我也尝试使用MySQL Connector / Python DB驱动程序而不是mysqlclient。它产生了一个不同的（但相似的）错误消息和回溯。
如果我回到SQLite，它运作正常。在django开发服务器而不是nginx下运行也可以正常工作。
我已经看到这个错误的帖子说明django CONN_MAX_AGE应该小于MySQL wait_timeout，但是我使用默认的CONN_MAX_AGE设置为0.根据django文档，将此设置为0（默认值）会导致django创建每个请求的新数据库连接。大于0的值将定义连接保持打开的时间长度，以便其他请求可以重用它。如果我将其设置为大于0的值，则错误消失，但我担心我只是将错误推迟到持久连接到期之后。此外，django开发Web服务器为每个请求创建一个新连接（类似于CONN_MAX_AGE=0），但我没有使用开发服务器获取错误。 1.6之前的Django版本不支持持久连接，所以看起来我应该能够保持默认的CONN_MAX_AGE=0设置。
我必须为uwsgi启用日志记录，它的错误日志显示以下内容：
*** Starting uWSGI 2.0.13.1 (64bit) on [Fri Nov 18 22:15:33 2016] ***
compiled with version: 4.8.4 on 18 May 2016 17:48:05
os: Linux-4.4.0-45-generic #66-Ubuntu SMP Wed Oct 19 14:12:37 UTC 2016
nodename: 083c33814e43
machine: x86_64
clock source: unix
detected number of CPU cores: 8
current working directory: /
detected binary path: /usr/local/bin/uwsgi
!!! no internal routing support, rebuild with pcre support !!!
uWSGI running as root, you can use --uid/--gid/--chroot options
*** WARNING: you are running uWSGI as root !!! (use the --uid flag) ***
chdir() to /srv/ftc
your memory page size is 4096 bytes
detected max file descriptor number: 65536
lock engine: pthread robust mutexes
thunder lock: disabled (you can enable it with --thunder-lock)
uwsgi socket 0 bound to UNIX address /srv/ftc/ftc.sock fd 3
Python version: 3.4.3 (default, Oct 14 2015, 20:31:36) [GCC 4.8.4]
Set PythonHome to /srv/env/ftc
*** Python threads support is disabled. You can enable it with --enable-threads ***
Python main interpreter initialized at 0x22a73d0
your server socket listen backlog is limited to 100 connections
your mercy for graceful operations on workers is 60 seconds
mapped 1476189 bytes (1441 KB) for 10 cores
*** Operational MODE: preforking ***
Loading configuration from /srv/ftc/data/settings_local.py
WSGI app 0 (mountpoint='') ready in 2 seconds on interpreter 0x22a73d0 pid: 9 (default app)
*** uWSGI is running in multiple interpreter mode ***
spawned uWSGI master process (pid: 9)
spawned uWSGI worker 1 (pid: 17, cores: 1)
spawned uWSGI worker 2 (pid: 18, cores: 1)
spawned uWSGI worker 3 (pid: 19, cores: 1)
spawned uWSGI worker 4 (pid: 20, cores: 1)
spawned uWSGI worker 5 (pid: 21, cores: 1)
spawned uWSGI worker 6 (pid: 22, cores: 1)
spawned uWSGI worker 7 (pid: 23, cores: 1)
spawned uWSGI worker 8 (pid: 24, cores: 1)
spawned uWSGI worker 9 (pid: 25, cores: 1)
spawned uWSGI worker 10 (pid: 26, cores: 1)
[pid: 21|app: 0|req: 1/1] 192.168.1.15 () {38 vars in 637 bytes} [Fri Nov 18 17:15:39 2016] GET /faq/ => generated 13018 bytes in 3021 msecs (HTTP/1.1 200) 8 headers in 412 bytes (1 switches on core 0)
[pid: 21|app: 0|req: 2/2] 192.168.1.15 () {40 vars in 707 bytes} [Fri Nov 18 17:16:20 2016] GET /find-local-food/ => generated 20480 bytes in 1510 msecs (HTTP/1.1 200) 7 headers in 290 bytes (2 switches on core 0)
[pid: 21|app: 0|req: 3/3] 192.168.1.15 () {40 vars in 711 bytes} [Fri Nov 18 17:16:23 2016] GET /my-programs/ => generated 9297 bytes in 1454 msecs (HTTP/1.1 200) 7 headers in 290 bytes (2 switches on core 0)
[pid: 21|app: 0|req: 4/4] 192.168.1.15 () {40 vars in 683 bytes} [Fri Nov 18 17:16:26 2016] GET / => generated 13562 bytes in 3037 msecs (HTTP/1.1 200) 8 headers in 412 bytes (2 switches on core 0)
[pid: 21|app: 0|req: 5/5] 192.168.1.15 () {40 vars in 683 bytes} [Fri Nov 18 17:16:30 2016] GET /about/ => generated 10064 bytes in 1586 msecs (HTTP/1.1 200) 7 headers in 290 bytes (2 switches on core 0)
[pid: 21|app: 0|req: 6/6] 192.168.1.15 () {40 vars in 685 bytes} [Fri Nov 18 17:16:33 2016] GET /faq/ => generated 13018 bytes in 1145 msecs (HTTP/1.1 200) 8 headers in 412 bytes (2 switches on core 0)
[pid: 21|app: 0|req: 7/7] 192.168.1.15 () {40 vars in 691 bytes} [Fri Nov 18 17:16:35 2016] GET /contact/ => generated 8734 bytes in 1352 msecs (HTTP/1.1 200) 7 headers in 290 bytes (2 switches on core 0)
[pid: 21|app: 0|req: 8/8] 192.168.1.15 () {40 vars in 711 bytes} [Fri Nov 18 17:16:38 2016] GET /find-local-food/ => generated 20480 bytes in 1484 msecs (HTTP/1.1 200) 7 headers in 290 bytes (2 switches on core 0)
[pid: 21|app: 0|req: 9/9] 192.168.1.15 () {40 vars in 699 bytes} [Fri Nov 18 17:16:41 2016] GET /about/ => generated 10064 bytes in 1723 msecs (HTTP/1.1 200) 7 headers in 290 bytes (2 switches on core 0)
Traceback (most recent call last):
File "/srv/env/ftc/lib/python3.4/site-packages/django/core/urlresolvers.py", line 393, in urlconf_module
return self._urlconf_module
AttributeError: 'RegexURLResolver' object has no attribute '_urlconf_module'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/srv/env/ftc/lib/python3.4/site-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
File "/srv/env/ftc/lib/python3.4/site-packages/django/db/backends/mysql/base.py", line 124, in execute
return self.cursor.execute(query, args)
File "/srv/env/ftc/lib/python3.4/site-packages/MySQLdb/cursors.py", line 250, in execute
self.errorhandler(self, exc, value)
File "/srv/env/ftc/lib/python3.4/site-packages/MySQLdb/connections.py", line 42, in defaulterrorhandler
raise errorvalue
File "/srv/env/ftc/lib/python3.4/site-packages/MySQLdb/cursors.py", line 247, in execute
res = self._query(query)
File "/srv/env/ftc/lib/python3.4/site-packages/MySQLdb/cursors.py", line 411, in _query
rowcount = self._do_query(q)
File "/srv/env/ftc/lib/python3.4/site-packages/MySQLdb/cursors.py", line 374, in _do_query
db.query(q)
File "/srv/env/ftc/lib/python3.4/site-packages/MySQLdb/connections.py", line 270, in query
_mysql.connection.query(self, query)
_mysql_exceptions.OperationalError: (2006, 'MySQL server has gone away')
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "/srv/env/ftc/lib/python3.4/site-packages/django/core/handlers/wsgi.py", line 170, in __call__
self.load_middleware()
File "/srv/env/ftc/lib/python3.4/site-packages/django/core/handlers/base.py", line 52, in load_middleware
mw_instance = mw_class()
File "/srv/env/ftc/lib/python3.4/site-packages/django/middleware/locale.py", line 24, in __init__
for url_pattern in get_resolver(None).url_patterns:
File "/srv/env/ftc/lib/python3.4/site-packages/django/core/urlresolvers.py", line 401, in url_patterns
patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
File "/srv/env/ftc/lib/python3.4/site-packages/django/core/urlresolvers.py", line 395, in urlconf_module
self._urlconf_module = import_module(self.urlconf_name)
File "/srv/env/ftc/lib/python3.4/importlib/__init__.py", line 109, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 2254, in _gcd_import
File "<frozen importlib._bootstrap>", line 2237, in _find_and_load
File "<frozen importlib._bootstrap>", line 2226, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 1200, in _load_unlocked
File "<frozen importlib._bootstrap>", line 1129, in _exec
File "<frozen importlib._bootstrap>", line 1471, in exec_module
File "<frozen importlib._bootstrap>", line 321, in _call_with_frames_removed
File "./ftc/urls.py", line 23, in <module>
url(r'^', include('areas.public.urls')),
File "/srv/env/ftc/lib/python3.4/site-packages/django/conf/urls/__init__.py", line 33, in include
urlconf_module = import_module(urlconf_module)
File "/srv/env/ftc/lib/python3.4/importlib/__init__.py", line 109, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 2254, in _gcd_import
File "<frozen importlib._bootstrap>", line 2237, in _find_and_load
File "<frozen importlib._bootstrap>", line 2226, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 1200, in _load_unlocked
File "<frozen importlib._bootstrap>", line 1129, in _exec
File "<frozen importlib._bootstrap>", line 1471, in exec_module
File "<frozen importlib._bootstrap>", line 321, in _call_with_frames_removed
File "./areas/public/urls.py", line 36, in <module>
url(r'^paypal/', include('areas.public.paypal.urls')),
File "/srv/env/ftc/lib/python3.4/site-packages/django/conf/urls/__init__.py", line 33, in include
urlconf_module = import_module(urlconf_module)
File "/srv/env/ftc/lib/python3.4/importlib/__init__.py", line 109, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 2254, in _gcd_import
File "<frozen importlib._bootstrap>", line 2237, in _find_and_load
File "<frozen importlib._bootstrap>", line 2226, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 1200, in _load_unlocked
File "<frozen importlib._bootstrap>", line 1129, in _exec
File "<frozen importlib._bootstrap>", line 1471, in exec_module
File "<frozen importlib._bootstrap>", line 321, in _call_with_frames_removed
File "./areas/public/paypal/urls.py", line 5, in <module>
from . import payment_complete
File "./areas/public/paypal/payment_complete.py", line 9, in <module>
PublicCommon = PublicCommon()
File "./areas/public/common/__init__.py", line 34, in __init__
self.login_page = self.get_cms_page('pu_login')
File "./areas/public/common/__init__.py", line 27, in get_cms_page
return get_object_or_404(Page, reverse_id=reverse_id, publisher_is_draft=False)
File "/srv/env/ftc/lib/python3.4/site-packages/django/shortcuts.py", line 155, in get_object_or_404
return queryset.get(*args, **kwargs)
File "/srv/env/ftc/lib/python3.4/site-packages/django/db/models/query.py", line 328, in get
num = len(clone)
File "/srv/env/ftc/lib/python3.4/site-packages/django/db/models/query.py", line 144, in __len__
self._fetch_all()
File "/srv/env/ftc/lib/python3.4/site-packages/django/db/models/query.py", line 965, in _fetch_all
self._result_cache = list(self.iterator())
File "/srv/env/ftc/lib/python3.4/site-packages/django/db/models/query.py", line 238, in iterator
results = compiler.execute_sql()
File "/srv/env/ftc/lib/python3.4/site-packages/django/db/models/sql/compiler.py", line 840, in execute_sql
cursor.execute(sql, params)
File "/srv/env/ftc/lib/python3.4/site-packages/django/db/backends/utils.py", line 79, in execute
return super(CursorDebugWrapper, self).execute(sql, params)
File "/srv/env/ftc/lib/python3.4/site-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
File "/srv/env/ftc/lib/python3.4/site-packages/django/db/utils.py", line 98, in __exit__
six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/srv/env/ftc/lib/python3.4/site-packages/django/utils/six.py", line 685, in reraise
raise value.with_traceback(tb)
File "/srv/env/ftc/lib/python3.4/site-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
File "/srv/env/ftc/lib/python3.4/site-packages/django/db/backends/mysql/base.py", line 124, in execute
return self.cursor.execute(query, args)
File "/srv/env/ftc/lib/python3.4/site-packages/MySQLdb/cursors.py", line 250, in execute
self.errorhandler(self, exc, value)
File "/srv/env/ftc/lib/python3.4/site-packages/MySQLdb/connections.py", line 42, in defaulterrorhandler
raise errorvalue
File "/srv/env/ftc/lib/python3.4/site-packages/MySQLdb/cursors.py", line 247, in execute
res = self._query(query)
File "/srv/env/ftc/lib/python3.4/site-packages/MySQLdb/cursors.py", line 411, in _query
rowcount = self._do_query(q)
File "/srv/env/ftc/lib/python3.4/site-packages/MySQLdb/cursors.py", line 374, in _do_query
db.query(q)
File "/srv/env/ftc/lib/python3.4/site-packages/MySQLdb/connections.py", line 270, in query
_mysql.connection.query(self, query)
django.db.utils.OperationalError: (2006, 'MySQL server has gone away')
[pid: 20|app: 0|req: 1/10] 192.168.1.15 () {40 vars in 701 bytes} [Fri Nov 18 17:16:43 2016] GET /my-programs/ => generated 0 bytes in 258 msecs (HTTP/1.1 500) 0 headers in 0 bytes (1 switches on core 0)
...brutally killing workers...
worker 1 buried after 1 seconds
worker 2 buried after 1 seconds
worker 3 buried after 1 seconds
worker 4 buried after 1 seconds
worker 5 buried after 1 seconds
worker 6 buried after 1 seconds
worker 7 buried after 1 seconds
worker 8 buried after 1 seconds
worker 9 buried after 1 seconds
worker 10 buried after 1 seconds
binary reloading uWSGI...
chdir() to /
closing all non-uwsgi socket fds > 2 (max_fd = 65536)...
found fd 3 mapped to socket 0 (/srv/ftc/ftc.sock)
running /usr/local/bin/uwsgi
[uWSGI] getting INI configuration from /srv/ftc/conf/uwsgi.ini
在此先感谢您的帮助！
这通常是一个mysql配置问题。您要为网站调整的设置特别是：
但是如果你看看你的日志，mysql消失的问题只是在处理由其他地方引起的异常时。在尝试解决mysql问题之前，我会首先尝试解决此异常
Traceback (most recent call last):
File "/srv/env/ftc/lib/python3.4/site-packages/django/core/urlresolvers.py", line 393, in urlconf_module
return self._urlconf_module
AttributeError: 'RegexURLResolver' object has no attribute '_urlconf_module'
我找到了解决方案。我向uwsgi.ini添加了lazy-apps。见ningx, uwsgi, python permanent mysql error after some time from starting application
我没有使用sql炼金术，但这确实修复了mysql服务器已经消失的错误。