Rails产生“PGError：服务器意外关闭连接”经过一段时间后 [英] Rails produces "PGError: server closed the connection unexpectedly" after some timeout

问题描述

我的Rails应用程序设置如下：

• 在RHEL 5.6上运行的Rails：3.0.5


• Postgres：8.4，在Windows Server 2008上运行
  两个服务器在同一个LAN上。

问题是，在一些空闲时间后，当我向Rails应用程序发出新的请求时，它会给我以下错误：

  ActiveRecord :: StatementInvalid（PGError：服务器意外关闭连接
这可能意味着服务器在处理请求前或处理请求时异常终止
 
  

根据我研究的内容，似乎数据库连接在Postgres超时后被删除，在这段时间内， / p>

• 如果我向Rails发出请求（第一个请求），它将显示上面的连接错误

<如果我向Rails发出另一个请求（第二个请求），Rails似乎重新连接到Postgres并正常工作。

我将永远遇到第一个连接错误，然后将所有的正常操作，这是非常严重的在我的情况，因为我想提交一个无错误的响应，我的客户端。

我已查看过以下问题和答案，但它们似乎不适合我的情况：

• PGError：没有到服务器的连接 （Ubuntu for DB server）


• 如何在Postgresql中使用tcp_keepalives设置？（MacOS中的Keepalive）

任何建议，以使我的应用程序从db连接错误免费？谢谢。

解决方案

我们在Heroku上有很多问题。作为一个hackish解决方案，这里是我们做的。将以下内容放在您的ApplicationController中：

  prepend_before_filter：confirm_connection 
 def confirm_connection 
c = ActiveRecord :: Base.connection 
 begin 
 c.select_allSELECT 1
 rescue ActiveRecord :: StatementInvalid 
 ActiveRecord :: Base.logger.warn重新连接到数据库 
 c.reconnect！ 
 end 
 end 
  

基本上，测试每个控制器命中的连接。可扩展？不是真的。但它为我们解决了这个问题。

I have the setup of my Rails app as following:

• Rails: 3.0.5 (under Apache proxy) running on RHEL 5.6
• Postgres: 8.4, running on Windows Server 2008 The 2 servers are on the same LAN.

The problem is, after some idle time, when I make a new request to the Rails app, it gives me the following error:

ActiveRecord::StatementInvalid (PGError: server closed the connection unexpectedly
    This probably means the server terminated abnormally
    before or while processing the request.

From what I have researched, it seems that the database connections are dropped after some timeout by Postgres. During this time, from the Rails side,

• if I make a request to Rails (1st request), it will display the connection error as above
• if I make another request to Rails (2nd request), Rails seems to reconnect to Postgres and functions correctly.

It means that I will always experience the first connection error then will have all normal operation again, which is very serious in my case since I'd like to deliver a non-error response to my client.

I have looked in following questions and answers, but they do not seem to be appropriate for my case:

• "PGError: no connection to the server" after idle (Ubuntu for DB server)
• How to use tcp_keepalives settings in Postgresql? (keepalives in MacOS)

Do you have any advice in order to make my app free from db connection errors? Thank you.

解决方案

We had this problem on Heroku, a lot. As a hackish solution, here's what we did. Put the following in your ApplicationController:

prepend_before_filter :confirm_connection
def confirm_connection
  c = ActiveRecord::Base.connection
  begin
    c.select_all "SELECT 1"
  rescue ActiveRecord::StatementInvalid
    ActiveRecord::Base.logger.warn "Reconnecting to database"
    c.reconnect!
  end
end

Basically, tests the connection on each controller hit. Scalable? Not really. But it fixed the problem for us.

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