我有一个生产中的rails应用程序，我前几天部署了一些更改。突然之间，我每天多次收到错误ActiveRecord::ConnectionTimeoutError: could not obtain a database connection within 5.000 seconds (waited 5.000 seconds)，并且必须重新启动puma才能解决问题。
我完全不知道造成这种情况的原因。我没有更改服务器上的任何内容，我所做的更改非常简单（添加到视图并添加到控制器方法）。
我在日志文件中看不到任何内容。
我使用的是rails 4.1.4和ruby 2.0.0p481
关于为什么我的关系填满的任何想法？我的连接池设置为10，我使用默认的puma配置。
这是一个堆栈跟踪：
ActiveRecord::ConnectionTimeoutError (could not obtain a database connection within 5.000 seconds (waited 5.000 seconds)):
activerecord (4.1.4) lib/active_record/connection_adapters/abstract/connection_pool.rb:190:in `block in wait_poll'
activerecord (4.1.4) lib/active_record/connection_adapters/abstract/connection_pool.rb:181:in `loop'
activerecord (4.1.4) lib/active_record/connection_adapters/abstract/connection_pool.rb:181:in `wait_poll'
activerecord (4.1.4) lib/active_record/connection_adapters/abstract/connection_pool.rb:136:in `block in poll'
/usr/local/rvm/rubies/ruby-2.0.0-p481/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'
activerecord (4.1.4) lib/active_record/connection_adapters/abstract/connection_pool.rb:146:in `synchronize'
activerecord (4.1.4) lib/active_record/connection_adapters/abstract/connection_pool.rb:134:in `poll'
activerecord (4.1.4) lib/active_record/connection_adapters/abstract/connection_pool.rb:418:in `acquire_connection'
activerecord (4.1.4) lib/active_record/connection_adapters/abstract/connection_pool.rb:351:in `block in checkout'
/usr/local/rvm/rubies/ruby-2.0.0-p481/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'
activerecord (4.1.4) lib/active_record/connection_adapters/abstract/connection_pool.rb:350:in `checkout'
activerecord (4.1.4) lib/active_record/connection_adapters/abstract/connection_pool.rb:265:in `block in connection'
/usr/local/rvm/rubies/ruby-2.0.0-p481/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'
activerecord (4.1.4) lib/active_record/connection_adapters/abstract/connection_pool.rb:264:in `connection'
activerecord (4.1.4) lib/active_record/connection_adapters/abstract/connection_pool.rb:541:in `retrieve_connection'
activerecord (4.1.4) lib/active_record/connection_handling.rb:113:in `retrieve_connection'
activerecord (4.1.4) lib/active_record/connection_handling.rb:87:in `connection'
activerecord (4.1.4) lib/active_record/query_cache.rb:51:in `restore_query_cache_settings'
activerecord (4.1.4) lib/active_record/query_cache.rb:43:in `rescue in call'
activerecord (4.1.4) lib/active_record/query_cache.rb:32:in `call'
activerecord (4.1.4) lib/active_record/connection_adapters/abstract/connection_pool.rb:621:in `call'
actionpack (4.1.4) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
activesupport (4.1.4) lib/active_support/callbacks.rb:82:in `run_callbacks'
actionpack (4.1.4) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (4.1.4) lib/action_dispatch/middleware/remote_ip.rb:76:in `call'
airbrake (4.1.0) lib/airbrake/rails/middleware.rb:13:in `call'
actionpack (4.1.4) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
actionpack (4.1.4) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
railties (4.1.4) lib/rails/rack/logger.rb:38:in `call_app'
railties (4.1.4) lib/rails/rack/logger.rb:20:in `block in call'
activesupport (4.1.4) lib/active_support/tagged_logging.rb:68:in `block in tagged'
activesupport (4.1.4) lib/active_support/tagged_logging.rb:26:in `tagged'
activesupport (4.1.4) lib/active_support/tagged_logging.rb:68:in `tagged'
railties (4.1.4) lib/rails/rack/logger.rb:20:in `call'
actionpack (4.1.4) lib/action_dispatch/middleware/request_id.rb:21:in `call'
rack (1.5.2) lib/rack/methodoverride.rb:21:in `call'
dragonfly (1.0.5) lib/dragonfly/cookie_monster.rb:9:in `call'
rack (1.5.2) lib/rack/runtime.rb:17:in `call'
activesupport (4.1.4) lib/active_support/cache/strategy/local_cache_middleware.rb:26:in `call'
rack (1.5.2) lib/rack/sendfile.rb:112:in `call'
airbrake (4.1.0) lib/airbrake/user_informer.rb:16:in `_call'
airbrake (4.1.0) lib/airbrake/user_informer.rb:12:in `call'
railties (4.1.4) lib/rails/engine.rb:514:in `call'
railties (4.1.4) lib/rails/application.rb:144:in `call'
railties (4.1.4) lib/rails/railtie.rb:194:in `public_send'
railties (4.1.4) lib/rails/railtie.rb:194:in `method_missing'
puma (2.9.0) lib/puma/configuration.rb:71:in `call'
puma (2.9.0) lib/puma/server.rb:490:in `handle_request'
puma (2.9.0) lib/puma/server.rb:361:in `process_client'
puma (2.9.0) lib/puma/server.rb:254:in `block in run'
puma (2.9.0) lib/puma/thread_pool.rb:92:in `call'
puma (2.9.0) lib/puma/thread_pool.rb:92:in `block in spawn_thread'
Puma init.d脚本
#!/bin/sh
# Starts and stops puma
#
case "$1" in
start)
su myuser -c "source /etc/profile && cd /var/www/myapp/current && rvm gemset use myapp && puma -d -e production -b unix:///var/www/myapp/myapp_app.sock -S /var/www/myapp/myapp_app.state"
;;
stop)
su myuser -c "source /etc/profile && cd /var/www/myapp/current && rvm gemset use myapp && RAILS_ENV=production bundle exec pumactl -S /var/www/myapp/myapp_app.state stop"
;;
restart)
$0 stop
$0 start
;;
*)
echo "Usage: $0 {start|stop|restart}"
exit 1
esac
修改
我认为我最终使用airbrake方法current_user或{{1}将问题缩小为 devise gem和 } user_signed_in?中的application_controller.rb。
这是我的应用程序控制器：
before_action如果我删除class ApplicationController < ActionController::Base
protect_from_forgery
before_filter :authenticate_user!, :get_new_messages
# Gets the unread messages for the logged in user
def get_new_messages
@num_new_messages = 0 # Initially set to 0 so login page, etc works
# If the user is signed in, fetch the new messages
if user_signed_in? # I also tried !current_user.nil?
@num_new_messages = Message.where(:created_for => current_user.id).where(:viewed => false).count
end
end
...
end
块，我没有问题。自从我介绍了该代码以来，我的应用程序似乎耗尽了连接。如果我保留if块并删除airbrake gem，我的应用程序似乎运行得很好，只有我的if文件池中默认的5个连接设置。
修改
我终于弄明白，如果我在database.yml文件config/environments/production.rb中注释掉这一行，我就不会收到错误消息。似乎应用程序控制器before_action中的自定义路由+设计是原因。我在github上创建了一个问题和一个可重现的项目。
https://github.com/plataformatec/devise/issues/3422 https://github.com/toymachiner62/devise-connection-failure/blob/master/config/environments/production.rb#L84
答案 0 :(得分：6)
我遇到了同样的问题，这些问题是由于数据库的打开连接太多造成的。当您在控制器之外（模型，邮件程序，pdf生成器......）中有数据库查询时，就会发生这种情况。
我可以通过在这个自动关闭连接的块中包装这些查询来修复它。
ActiveRecord::Base.connection_pool.with_connection do
# your code
end
由于Puma工作多线程，因此池大小（如提到的eabraham）也可能是一个限制。尝试增加它（一点点）......
我希望这有帮助！
答案 1 :(得分：2)
在设计家伙的帮助下，我想我终于弄明白了这个问题。似乎通过使用自己的控制器自定义错误页面，我没有跳过before_action get_new_messages。所以非常简单的解决方法是添加：
skip_before_filter :get_new_messages
到我的自定义错误控制器。
此问题详细说明了这背后的原因：https://github.com/plataformatec/devise/issues/3422
答案 2 :(得分：0)
最终这个问题仍然困扰着我一年左右。我终于通过与美洲狮人一起工作得到了很好的解决方案。
将你的美洲狮升级到至少2.15.x。