I really like the concept of Getting Things Done. I’m also a fan of Inbox Zero. Well, at least try to be. Here’s how I implement GTD using my gmail account…
Continue reading GMail Getting Things Done – a poor man’s version
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Here’s an idea… Ever been in a LoadRunner contract where you’ve got a ton of scripts to write for business transactions that have many many design steps? Even worse, have you had to write those scripts against a development environment with an unstable code base and shocking performance? Sound familiar? Ever felt the frustration of re-recording manual test cases back into LoadRunner in said environments. Why wouldn’t you just automate the script recording process?
I’m often required to poll a database resource in some sort of daemon. For example, check a table for some asynchronous tasks to complete. If you have a lot of threads polling this resource at quick intervals, the impact on the resource can be excessive/high. Rather than poll at a set interval, I use a Fibonacci sequence to determine what the next sleep interval will be. Following are code examples of this polling technique hosted on GitHub in my most commonly used programming languages… Version control is not something you often associate with performance testing scripts. The reasons generally vary. A significant one is the lack of any version control support in commercial toolsets like LoadRunner. Another reason is the perceived short-term shelf life of test scripts. You tend to write them once and throw them away right? If you work with more agile teams/developers you will probably start to require a lot of re-use out of your scripts, especially when the release cycle increases in terms of frequency. It starts to make sense to use version control and some form of scripting framework. In this post I’m going to use JMeter as the tool of choice here and I’m going to re-introduce concepts which I normally force upon others whilst contracting. That is, use of Application Simulation Models (ASMs) to hep define the load and use of the Application Performance Index (Apdex) to help present results. I’m also going to use GitHub (or git) as my tool for maintaining version control and implementing a wiki as a dashboard replacement for other test management tools. A colleague recently asked me if %D, when used in your LogFormat for apache2 access logs includes the ‘download’ time of transmitting the response back to the client. Following are observations from my apache2 access logs when using the %D format code. The first column is %D in the following log entries. # 5 second pause on server side code. In this test case I deliberately induce a 5 second delay on server side code using the php sleep function. This delay can be seen in the timestamp (microseconds) # Static image open bandwidth. In this test case I let the browser download a static image as fast as my mobile broadband permits. The time takes approx 4.8 secs to download approx 900KB. # Static image restricted bandwidth. In this case I restrict the bandwidth to any destination port of 80 to 1KB/sec using ipfw[1]. This time it takes approx 12.8 secs to download the same file. [1] to restrict bandwidth on my mac I did this: To sum up, when using %D in LogFormat for apache2, this timestamp is increased by any: QED Here’s a simple Ruby script that will parse a remote GC log using Perl for specific date time entries. The scenario in which you might use this script is where you have rather large remote GC logs sitting on another platform like AIX that doesn’t have Ruby installed. It’s useful in the sense you can execute a load test, then just parse the GC log for the entries from the native_stderr.log that represent your test run. YMMV.
A colleague recently asked me if it was possible to test SAP portals using JMeter. The short answer is yes. Some people get confused with the additional protocols that LoadRunner sports for SAP, particularly the SAP GUI. But if your SAP portal uses plain old HTTP (or HTTPS) then JMeter can do the job. There are a few gotchas which I will continue to update on this post, namely around correlation. In JMeter, correlation is particularly *easier* because you don’t have to worry about where to position a correlation rule. The equivalent function to use is a Post Processor -> Regular Expression Extractor. I’ve been thinking about some promotional material for the company I work for. What inspired me was seeing a vi coffee mug… Unfortunately only available in the US. I’ve been endeavouring to wean myself off textmate and the like so thought this was a brilliant idea. But with limited space, what essential commands should go on a vim cheat sheet? What other cheat sheets would you like to see in this format? “Sparklines: Intense, Simple, Word-Sized Graphics” If you’ve been reading this blog for sometime, you will know I’ve got a certain penchant for sparklines, a term coined by Edward Tufte and referred to in his book titled “Beautiful Evidence” True sparklines are meant to be word-like graphics, such that they fit inline with the body of the text, however I’ve had difficulty implementing this with tools such as Excel or custom chart libraries like JFreeChart. The Google Chart API makes this relatively simple. To that end, my choice of implementation is to present inline with a paragraph. Say for example I wanted to display the amount of jobs advertised over 4 months, then my version of a sparkline would look like this: Sure, it’s pixelated, the colours are a little hard to differentiate, and the vertical axis is lacking a scale or unit of measurement. However this simple column chart does convey quite succinctly, when jobs are advertised, whether it is the start, middle of end of a month, and how many jobs are available per month. So what makes a perfect sparkline? To be honest, I don’t ever think sparklines should be used as a supplement for detail. I believe sparklines are best used in situations where you want to convey a lot of data in a small space. They really should be thought of as triggers, not from which you conduct a detailed analysis, but something which triggers the thought to pursue more information in the first place. Here’s another example recently used to show size of allocation failures on an IBM JVM heap. Cool? Go get em: http://en.wikipedia.org/wiki/Sparkline Well, as a performance test lead I’ve been getting more involved in the hiring process. To cut through the chaff, these are some of the questions I like to ask potential candidates. What’s your favourite questions? How might you answer these? I also like to follow up these questions with a half hour practical scripting in VuGen (or your tool of choice). You can learn alot about someone by the way they write their scripts. The point? Determine if the person has recently used the tool (you’d be surprised) and suss out general knowledge of performance testing… |
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