The Knitting Fiend

To all: I installed a new plugin: WP-Cache-2. I noticed some minor weirdness when I first installed, but figured out how to fix that very quickly. Altogether, it took me about 10 minutes to install the plugin. However, this plugin can have a major effect on my site. So, if you notice any ‘weirdness’ of any type while reading the blog, let me know! (If you notice it loads more quickly or slowly, let me know that too. It should mostly load more quickly– that’s a side effect!)

Those interested in why I installed WP-Cache-2, read below. Since this is a knitting blog, I’ve tried to discuss the issue in terms a typical knit - blogger might understand.

Surfing some other blogs, it came to my attention that Dreamhost and other web hosts sometimes get huffy if someone with a low priced account uses up way too much cpu One of the blogs I read had some difficulties in that regard.¹ Being curious, I checked out my cpu usage at Dreamhost and discovered that I use nearly an hour of cpu a day!

Now, I use Dreamhost, and strictly speaking, Dreamhost, doesn’t have a limit on cpu usage. Dreamhost’s official policy is that as long as a customer isn’t bringing a server to it’s knees², they will work with the customer. But, the fact is, I don’t have the slightest clue how much cpu might bring a server to its knees. Could an hour/day of cpu do that? 10 hours/day? 100 hours/ day? Am I anywhere near “close” to the flexible limit?

To educate myself, I decided to surf and discovered that Dreamhost used to impose a 1 hour a day cpu limit on economy users like myself. So, I figure that means 1 hour is approaching my ‘fair share’ of cpu. I concluded it would be wise to explore methods to cut cpu usage.

I read a bit, and discovered many recommend installing WP-Cache-2, which ‘caches’ pages on the server. What’s this mean? Well, ordinarily, when a visitor loads a url for a Wordpress blog, what really happens is they send the server a request to run a program. That program creates the html for the page and then sends the html to the visitors browser. In contrast, static web pages are stored as html files on the server; the server doesn’t need to run a program to create them every time a visitor loads a page.

Running the program requires ‘cpu’. I use 1 hour a day. That’s a bunch; I want to use less.

So, WP-Cache-2 save cpu? WP-Cache-2 does several things, but the important part from the point of saving cpu is that after someone view a page, WP-Cache-2 saves the html and stores it in a “cache”. The next time someone visits, WP-Cache-2 checks to see if a page is stored in cache, if it is, it shows them that page; if there is no cached page, it recreates one.³

Ok, so where is the downside? Well, in principle, the downside is that when pages are cached, they take up bandwidth. Years ago, people on economy hosting packages had fairly small bandwidth limits. This is no longer the case, my $7.95/month hosting gives me more bandwidth than I could ever, ever, ever use. Nowadays, CPU is expensive, bandwidth is cheap. So as far as I can tell, there is no big downside to caching the pages.⁴

I’ll be testing this over the next few days, and I’ll report whether I save any CPU. Let’s hope so!

---

Footnotes:
1. Alas A Blog’s cpu problems.
2. The specific comment plugin Barry Deutsch of “Alas a Blog” used really can, and did bring a server to its knees. He runs a political blog, and feels using a fairly complex plugin for his comments is important. Like most knit bloggers, I don’t run the type of comments list Barry Deutch uses, so I’m not likely to experience exactly the problem he had.
3. WP-Cache-2 also periodically deletes the page from cache, and does some rational things like automatically delete the page from cache when comments are added. That way people can still read the comments.
4. Caching may also not do you much good if your blog gets a new comment every minute and you display any sort of recent comments on the sidebar.
5. If you are looking for inexpensive hosting, I am happy with Dreamhost’s inexpensive hosting.