"Plugins" Posts

Memory Profiler Plugin

By Derek Bullet_white Posted in Plugins Bullet_white Comments Comments

Swap memory is like pushing your car downhill when it’s all out of gas. Sure you’ll keep going, but just not as fast. Oh, and use too much, and you could be in trouble.

In our experience, when a significant amount of swap memory is used, our web application performance slows down dramatically. Swap memory is just a lot slower than physical memory.

Eric Lindvall has created a nice plugin that profiles a system’s memory usage, returning the following information:
  • Swap Total
  • Swap Used
  • % Swap Used
  • Memory Total
  • Memory Used
  • % Memory Used

View the Memory Profiler Plugin


Monitoring Your Rails Sessions With Scout

By Derek Bullet_white Posted in Plugins Bullet_white Comments Comments

An oft-forgotten maintenance issue on Ruby on Rails applications is forgetting to expire old sessions. Lots of sessions in your database can dramatically slow performance.

You can use a cron job to expire old sessions, but it’s not always foolproof. We’ve seen timeouts when attempting to delete lots of session records and it’s not out of the range of possibilities to mistakenly disable multiple cron jobs.

Tim Morgan provided the inspiration for our latest plugin, Rails Session Monitoring. The plugin is dirt simple, reporting back the total number of sessions and the number of old sessions (you can define what constitutes old – the default is 14 days).

Here’s what I saw when I ran it on of our apps:


This is also the type of plugin that you don’t really need to run frequently – once-per-day is probably fine.


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