System monitoring daemon that can generate alerts
 

Hi Folks,
I'm looking for some kind of monitoring daemon to beat the system near-freezes that I've been seeing on my Ubuntu install on a regular basis. These are not due to one particular app, and it's partly due to memory leaks in apps that I won't stop using anytime soon (Firefox etc).

However, in the mean time my rig freezes pretty regularly due to memory/CPU overload.

I'm looking for something that'll ideally do the following:
1. Monitor CPU usage of the system as a whole, and notify me when it hits a user-defined high-water mark.
2. Similarly monitor memory usage.
3. As part of the notification, tell me which app ( or apps ) contribute the max to the CPU/memory usage.
4. At a 2nd high-water mark for CPU/memory, trigger a separate user-defined action ( typically kill the offending process ) as a preemptive measure to having the system freeze.

Do you know of any software that can do this, or something similar, or can be adapted by me to do this ? ( using scripting )

I'm looking for a deamon kind of process that does it's thing unobtrusively in the background and notifies me when required, and not a process like top ( or its derivatives ) where I need to keep an eye on the output.

Appreciate any thoughts or suggestions.

I can remember Nagios, ZenOss and cacti.
They are intended to monitoring several servers ans devices, not just one, thought.
However, if you go with one of theses programs, you can have all the features you listed and much more.
The best approach is to install one of theses programs in a monitoring machine (your desktop ?) and install the so called "agents" on the monitored machine (your problematic server).
By your description looks like it is not exactly what you are looking for. But may be you can take a look and expand your original requirements.

I am a big fan of Nagios and I use it to get an overview of all the network I am responsible for. I am considering to switch to Zenoss which is more advanced and easy to configure and manage.