When ColdFusion is maxing out the CPU, how do I find out what it's chewing/choking on?

Question

I\'m running CF 9.0.1 on Ubuntu on an \"Medium\" Amazon EC2 instance. CF has been seizing-up intermittently (several times per day...but notably not isolated to hours of pea

Answer 1

To find out what is maxing out your procs requires a lot of information that is "internal" to your system. It's hard to do it from outside looking at things like queued requests etc. One thing is certain - altering simultaneous request setting to a very high number is not going to do the trick :) All it will do is remove something that is designed to keep CF from gloaming onto too much processor.

Here's my list of things that max out CPU usage.

• Client vars in the registry. I have a couple of excellent articles on why this problem can "crop up" out of no where. check out my blog (coldfusion muse).
• intermitent problems connecting to the database. This is actually a little bit exacerbated in the cloud where networking and restrictions on bandwidth usage can sort of "throttle" connections to a DB. Most CF apps make heavy use of the DB. If something interferes with or slows connections the result is the number of connections rises til it hits that simultaneous number then requests start to queue - but this issue isn't necessarily related to CF itself - it's a symptom.
• JVM issues - tuning your JVM to handle garbage collection, have enough New and Perm gen space etc is very important... although frankly the items above are often the first at fault.

There are many other reasons this can happen - among them (as you surmise) code issues that crop up as certain scripts are run. Long running requests, file uploads, heavy lifting scheduled tasks, index bot traffic generating traffic or spawning too many sessions.... the list goes on.

Hopefully something on this list I provided will strike you as possible. good luck.

(and yes FR or even the CF monitor are good tools to help you tease all this out :).