But the CF Server Monitor does have an Achilles Heel: you may turn on one of its "start" buttons, especially "memory tracking", and find that it's crippling your server. You may not be able to then turn off the feature.
I talked about this potential issue in an entry when CF 8 was released back in 2007, CF Server Monitor: what's the impact on production? you may be surprised. I clarify there that the monitor will not, as some assert, "always kill your server". See that for more details.
And I discussed in an entry earlier today that you can't just "close the monitor" or even restart CF to make the problem go away, because that won't stop the functionality. See CF911: Using the #ColdFusion Server Monitor? Be aware that the "Start" buttons remain enabled.
So what if you are in a situation where using one of the features, especially typically "memory tracking", has in fact sent your server into a tizzy. If you can't even get into the monitor to turn it off, you're going to be in quite a pickle, and understandably panicked.
Easy solution if you're on CF 9.0.1
Fortunately, if you're on CF 9.01 and above, Adobe has addressed this problem. A hidden gem is that they added a new "monitoring settings" option in the CF Admin, and on that page there are checkboxes where you can control enabling/disabling the 3 start buttons from within the Admin, without having to open the Server Monitor.
Assuming you can at least get into the CF Admin, just disable one or all of the tracking features, and it will take effect immediately. (There could be a lingering impact that may last a little while as things settle down.)
That's a great addition.
But what if you are not on 9.0.1? Or what if you can't get into the Admin? Well, in the latter case you could try restarting CF to see if you could get in during the moments before it starts going nuts again, but you may have to resort to the following solution.
What to do in CF 8 or 9.0, or if you can't get into the Admin in 9.0.1
If you're on CF 8, 8.0.1, or 9.0, you won't have that feature above. And if you can't get into the monitor to turn them off (or even can't get into the Admin on 9.0.1), then you'll need to edit an xml file yourself to disable the feature(s) and restart CF.
(Let me say first that if you find that you simply "can't SEE" the "start" buttons at the top of the server monitor to turn them off, that's a different problem. Just hit the refresh button in your browser. Generally, that makes them appear. I've reported this problem to Adobe and let's hope they may fix it some day.)
Fortunately, you can disable the "start" buttons by directly editing the [cf]\lib\neo-monitoring.xml file. (On multiple instances, it's deep within the instance, such as for instance C:\JRun4\servers\cfusion\cfusion-ear\cfusion-war\WEB-INF\cfusion\lib.)
Warning: make a copy of the xml file before editing it, to be able to restore it in case you make any sort of mistake and need to recover.
In the xml file, set the entries related to monitoring to be "false", such as for:
The others are monitoringenabled and profilingenabled.
You will need to restart for these to take affect (and sometimes it's necessary to stop CF before changing these files, to ensure CF doesn't write to them on shutdown.)
Hope that's helpful to someone.
What about the "monitoring server" option in CF 9.0.1?
Some may wonder if the the other new setting in CF 9.0.1's "monitoring settings" page, the "Enable Monitoring Server" option, may be of significance here. Well, yes and no. That, too, is deserving of its own entry. But it does not change at all what I talk about above. More to come.