"Plugins" Posts
April 23, 2008 by Charles
Posted in Plugins | no comments 
Sometimes, the simplest ideas make for the best plugins.
Let’s say you have some process that always needs to be running (maybe that’s a ferret server or a backgrounDRb server) or maybe it’s just Apache.
Install the Keep Process Running Plugin and Scout will help make sure that process is always running.
The plugin simply scans the active running processes, and checks to see if that process is running. If it can’t find it in the active process list, it will attempt to run the restart action. You can specify anything, so if you need to perform some special startup task (/usr/bin/apachectl start) it can do that. If you do not specify a restart action, it simply re-runs the command it is looking for. This actually works well in most cases.
If you have any feedback or suggestions on this plugin feel free to comment on the plugin itself.
April 22, 2008 by Derek
Posted in Plugins | no comments
Ever wanted to track how many people are logged into your server? Mark Hasse built an Active Logins plugin that does just that, returning the total number of people logged in via console, ssh, telnet, etc.
Mark has built several other plugins as well:
It’s easy to create a Scout a plugin and we’re here to help. Some useful plugin resources:
April 17, 2008 by Derek
Posted in Plugins | no 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
April 16, 2008 by Derek
Posted in Plugins | no 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.
