Aaron Bushnell's questions

I’d like to know if there is a PHP/MySQL configuration option (or combination of options) that can prevent long-running PHP scripts in a small number of places from creating hanging and sleeping MySQL transactions that accumulate and can cause the entire MySQL server to crash.

Here’s the scenario I’m looking to avoid:

Let’s say I've launched a new site and one of the sections has a really inefficient PHP loop that never got addressed or was unforeseen. Once the site launches and it sees a huge amount of traffic the query rears its head and we receive 504 errors.

At this point we're accumulating a massive amount of sleeping MySQL connections and, if we hit our max connection limit, it brings down the database server and the rest of the site with it. All because one query on one page.

What I'm hoping to do is to prevent badly performant Twig/PHP code from having even the possibility of bringing down the server. Some mechanism or set of server config options that would cause the user on just that page to see an error, preventing hanging transactions, and keeping the database from a catastrophic failure that would affect everyone else.

I’m aware that, ultimately, the query itself needs optimization. But what I’d like to do is setup preventative measures that keep the servers from crashing for the other users on the site.

Does something out there exist to prevent this?

I am deploying my Github repo to a Media Temple Grid Server using Capistrano. In order to do this, I've setup the following:

• Enabled logging into the remote server with SSH keys (following this guide)
• Created an SSH key on the remote server and added the SSH keys to Github (so I can pull/clone a repo from Github)
• Setup my Capistrano deploy.rb file with set :use_sudo, false and default_run_options[:pty] = true because I am connecting and deploying with SSH keys and want to be as secure as possible

I'd like to know if this is:

1. Secure: Is my workflow secure?
2. Conventional: Is this the orthodox way of setting up this workflow?

Unfortunately, I was unable to use SSH agent forwarding with the Grid Server. I understand this is easier (and potentially safer) than creating SSH keys on the remote server and sharing them with Github.