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Devon Hillard Tech Blog

Java, ATG, Seam, and related Technologies

Why Is User Experience Performance So Important?December 31 2008

In my ATG Performance Tuning post I mentioned that how a user perceives the site performance impacts their behavior on the site, and that a fast site leads to more purchases/traffic/etc...

Here are some numbers to back that up:

• Amazon found that a 100ms increase in page response time led to a 1% DROP in sales, or conversely improving a page response time by 100ms will increase sales 1%. I suspect that this effect continues beyond the 100ms mark, but probably tapers off at some point.
• Google found that an 500ms increase in page response time led to a 20% drop in traffic and revenue. This is despite the 3X increase in search results delivered (30 results instead of the default 10) to the test group.
• Google also found that a 30% reduction in page size resulted in 30% more traffic/usage due to faster loading and rendering.

Given the relatively low cost/time in performance tuning your application, the resultant gain of 1%-20%+ in revenue makes it a smart move.

"As Google gets faster, people search more, and as it gets slower, people search less"
-- Marissa Mayer, Google vice president of search products and user experience

This is also true for your website, just replace search with "buy", "read", etc...

In fact, I'll lay down a wager: If you improve the page rendering time of the mo

Apache mod_deflate and mod_cache issuesNovember 18 2008

The Problem: Using Apache mod_deflate and mod_disk_cache (or other mod_cache) together can create far too many cached files.

The Background: Apache is a web server with many different modules you can load in to enhance it. Two common ones are mod_deflate and mod_cache (or mod_disk_cache).

Mod_deflate compresses content that is sent to the webserver using gzip. It can take 100k of html, css, or javascript, and compress it down to ~10k, before transmitting it to the user's browser. The browser then uncompresses it, and displays the page. Most web servers (depending on how your site/application is structured anyway) are not CPU limited. Therefore, you can spend some extra CPU doing the compression, and get much faster content delivery times to your users, who are often bandwidth limited. Not only does this make pages load faster for your users, but it also allows request handling threads to complete sooner, letting your web server handle more requests.

Some web browsers are not able to handle gzipped content correctly, therefore it's important to add in some logic to only send gzipped content to browsers who can handle it. Also, there are different types of files which are already compressed and hence trying to gzip them is a waste of time and resources, such as images, video, etc...

A common configuration may look like this:

# Insert filter SetOutputFilter DEFLATE # Netscape 4.x has some problems... BrowserMatch ^Mozilla/4 gzip-only

Why I Won’t Deal With Trans-AmericanOctober 30 2008

Generally I'd never post about a negative business interaction. We've all worked with bad recruiters, bad employers, bad contractors, and so on. I like to give people the benefit of the doubt, and I don't want to bad-mouth anyone.

That said, Trans-American has pushed my limits too far. These guys are some sort of ATG recruiting firm or something, I really don't know. They started calling me perhaps 6 weeks ago, asking if I was interested in a position. I told them very clearly, that I was on a contract which I was very happy with. That I would be at least through the end of the year. And they could call again in January. The same guy called again the next week. And twice every week since. I could not have been more clear, every single time. I was polite, but clear that I was not interested. And it was the same guy calling every time. I don't know how many ATG architects named Devon at my phone number he's dealing with, but the complete inability to respect my clear wishes, is amazing.

I will never do business with Trans-American, and I would recommend that everyone else avoid them as well.

10MinuteMail Performance ImprovementOctober 21 2008

After having a clearly better approach to mail delivery pointed out to me by a friend yesterday, I pushed a new version of 10MinuteMail out last night. End users shouldn't notice anything different, but behind the scenes the mail acceptance and delivery is MUCH higher performing. There should be less incoming mail delays, slow pages, and less domain changing. Inactive e-mail addresses will return a bounce notice now, as they probably should have done from the start.

I apologize for the delivery issues yesterday, before I made the change, the amount of incoming junk was really slamming on the server. Hopefully that's a thing of the past now.

Huge Logs and OS XAugust 22 2008

Another reason that I love my mac: it can handle 1.3 GB log files easily with built in tools. I recently received a huge log file in zipped form from a co-worker with the warning "good luck opening it, textpad won't open it."

After unzipping it to the full 1.3 GB size I was able to open it using the built in Apple log viewer Console.

I ended up mostly using the terminal and tools like cat, less, grep, etc... to quickly find what I wanted and view the log lines surrounding the events I was interested in.

No problem.