Comments on: Tangling with the Template Cache

By: charlie arehart

charlie arehart — Thu, 01 Mar 2007 15:40:37 +0000

Thanks, Ashwin. Are you saying that the CF8 monitoring *will* offer this as a measure? That’s good to hear. It doesn’t help all those on 6 and 7 who really need a way to measure this statistic.

I’ve not yet tried it (reconfigured my machine and run tests to confirm) but since the CFSTAT still reports it, can anyone reading this indicate if they’ve seen it showing a value when indeed the template cache size is set lower than the number of templates requested?

I offer that (as well as the nod to CF8) to give some consolation to others who may come along here and ask/look for this. Thanks again.

By: ashwin

ashwin — Thu, 01 Mar 2007 08:23:26 +0000

For CF 8, need I say - server monitoring?
As to why it’s not there, I don’t have a clue. Perhaps just one of those things that were dropped as we went from CF 5 to MX.

By: charlie arehart

charlie arehart — Thu, 01 Mar 2007 08:06:54 +0000

Ah, thanks for that clarification. Ok, so it does them seem we need a way to know when such pops are happening. That counter was the way before. Any thoughts on why it’s not there? And if an oversight, might it be put back in 8?

By: ashwin

ashwin — Thu, 01 Mar 2007 06:53:21 +0000

On the contrary, Charlie, the template cache is most definitely popped. The soft cache can grow only as large as the JVM will allow it to; templates that need to get compiled beyond the limits of the soft cache will trigger a cache pop of an older template so they can get in.

The more common case is that the soft cache will grow in size initially, and then shrink whenever the JVM needs memory, causing cache pops again.

Increasing the perm size, as Brandon suggests in his presentation, is probably a good idea if you’re sizing your template cache up. As he also points out, this is a trial and error kind of thing - it is also highly dependent on the size of the templates, and hence the generated class files.

Oh, and I’ll see about getting a Wordpress plugin to automatically send out email for comments.

By: charlie arehart

charlie arehart — Thu, 01 Mar 2007 05:57:43 +0000

Thanks, but here’s a more pertinent question: would it even matter? Now that I think of it, on rereading your entry, it seems possible that you’re saying that the template cache is never popped, with the new soft cache you describe. So that would be the question to ask: can the template cache ever fill? If not, then there will never be a cache pop.

The real question, then, is simply how does one go about choosing the best size for the template cache? What measure do we have to know if we’ve made it too large or too small?

Also, Ashwin, can you configure your WordPress setup to enable us to choose to receive email notifications of new comments posted here? Since it asks for our email address I assumed it would, but I’m not finding that it does. Thanks
And I’ve seen other info (http://www.bpurcell.org/presentations/usergroups/ColdFusion_Performance_Tuning.pdf) to suggest that if one does increase it over the default of 1024 then one should also double the maxpermsize. Any thoughts on that?

By: ashwin

ashwin — Wed, 28 Feb 2007 05:14:59 +0000

Charlie - I don’t have an answer for your myself, since I haven’t been around long enough. However, a quick poll in the team indicates that cache pops is probably not reported in Perfmon with CFMX.

By: charlie arehart

charlie arehart — Tue, 27 Feb 2007 07:32:33 +0000

Ashwin, I just observed that while the cp/sec stat is indeed still reported by CFSTAT in CFMX 6 and 7, I was working with a client running CFMX 6 and we couldn’t find it reported in his Perfomon’s CFMX6 performance object. And I couldn’t find it in my Perfmon’s CFMX 7 performance object. Do you know, or can anyone else report, if this is a known limitation in CFMX and above? It’s there in my CF5 performance object. Thanks.

By: ashwin

ashwin — Fri, 08 Sep 2006 13:42:24 +0000

No whitepaper, as far as I know, but I believe you can find the necessary information in the “Configuring and Administering ColdFusion MX” book that comes in the box with CF.

By: Marc Esher

Marc Esher — Fri, 08 Sep 2006 11:37:53 +0000

Is there an official whitepaper that describes the cache behavior, i.e. demonstrating that CF doesn’t actually access the .cfm file every time it is requested?

We’re trying to move all of our code off of our webservers and onto a central location (SAN), but the network people aren’t letting us because they claim it’ll result in much increased network overhead since “the webservers will have to travel the network every time to fetch the file from the SAN”.

Thanks.

By: monkeywoo

monkeywoo — Wed, 19 Jul 2006 17:39:02 +0000

Bob Everland,

You can clear your template cache with some code like this:

createObject(”component”,”cfide.adminapi.administrator”).login(”ohnoyoudont”);
createObject(”component”,”cfide.adminapi.runtime”).clearTrustedCache();