Over the pond, America is gearing up for Thanksgiving and their online retailers are preparing for their busiest weekend of the year. In common with America, in the UK there is a significant shift away from bricks and mortar retailers, towards online shopping. Visa Europe has already dubbed 2nd December “Mega Monday” and anticipates £450m of online spending on that day (£5,208 per second).
It may be too late to consider comprehensive performance testing to improve your website’s performance in time for this Christmas rush; but it isn’t too late to do some last minute housekeeping to help your web servers survive the onslaught. My friend and fellow performance testing specialist, James Pulley (PerfBytes, LoadRunner by the hour and NewCOE) posted this advice on Facebook earlier this week. Following his advice could just save you from embarrassment when your retail site comes under load….
“Ladies and Gentleman, it is time for your final cache management checks":
(1) If you have a CDN provider then make sure your provider settings are “primary” for your cache management. In other words, double check that the cache is being used.
(2) Check your logs. Count the number of instances of each request for the past 24 hours. Hint: Splunk and LogParser are great tools for this. Where you have large numbers of requests for specific object types, such as fonts, images, style sheets, etc..., make sure this MIME class is covered effectively by both your on-web-server cache management settings and your CDN provider. This is a “belts and braces” model in case cache priority gets switched accidentally.
(3) A 404 is always a cache “miss” and an expensive one at that because it involves network, CPU and multiple disk writes for the error. Check your error logs and count the number of errors by request. Consider "faking out" some high volume requests with an empty single byte file of the name requested for text format, or a single pixel alpha channel image where an image has been requested.
"Make the changes as soon as you can so that hopefully it will propagate through to your CDN caches in time for the rush!”
At Trust IV we take a keen interest in web application performance. We use our own in-house developed application to monitor the performance of hundreds of retail and other websites sites on a daily basis, and we’re looking forward to seeing the winners and losers in this Christmas’ web performance battle. We’ll publish our findings on this blog and through our Twitter feed, but if you’re interested in how your site is performing, you can always use our public WebPageTest instance. Hosted in Manchester you can see how real users experience your website. (Browse to http://www.webpagetest.org/ and choose Manchester, UK from the “Test Location” drop-down.)