HOW TO TURN A GREAT APP INTO A KILLER APP Trade secrets from Red Gate Software

Transcription

1 HOW TO TURN A GREAT APP INTO A KILLER APP Trade secrets from Red Gate Software By Red Gate Software

2 Introduction Developing a.net application is a bit like running the gauntlet. You spend months solving one complex problem after another, all the time working to tight deadlines. However many issues you fix, one recurring and frustrating problem remains Performance. Web pages that take too long to load, an unresponsive shopping cart or, worse still, an application that hangs performance issues can manifest themselves in all sorts of ways. Whether you're developing desktop applications, web applications, or Windows services, all good.net developers need optimum performance from their code. Here, we aim to show you that.net developers don't need to spend hours blindly chasing performance problems, when they could quickly and easily achieve that optimum performance. We also outline why it is crucial to investigate performance early on in the development process. Optimize your.net code the quick and easy way When an application a few thousand lines long runs slower than it should, you need a good code profiling tool. ANTS Profiler Pro takes the guesswork out of optimizing.net code. Easy to use The design of ANTS Profiler Pro means that you can profile your application within minutes, without having to read any manual. The simple four-step wizard makes.net code profiling straightforward. There is no scripting involved, and you do not need to spend time learning how the profiler works. Integrated into Visual Studio The integration of ANTS Profiler within Visual Studio 2003 and 2005 makes life even easier, since you can now launch the profiler from within VS.NET, while writing your application.

3 ANTS Profiler is launched, and the wizard opens up with the executable path already set Fast Mode or Detailed Mode With ANTS Profiler Pro, you can choose a fast profiling mode or a detailed one. When you just need an overview of your slowest methods, the Fast Mode is recommended. It introduces a minimum overhead into your application and shows you how long each.net method spends executing. The Detailed Mode profiles methods and lines, showing how long individual lines of code take to execute. This is particularly useful if you need to drill down into the slowest methods, or when you need to know the exact lines of code where performance bottlenecks are occurring.

4 Clear results The user-friendly results display is divided into two panes. The upper pane displays a summary of the profiling, and lists the 10 slowest lines of code, and the 10 slowest methods. The lower pane shows the source code, with line numbers, hit counts, and the time spent executing each line. Red bars show you where the total time spent executing particular lines is high, and an inefficient algorithm has been implemented. Profiling API More advanced users will find the profiling API particularly useful for the extra flexibility and control which it gives you over the profiling process. It lets you take snapshots exactly where you want within your application, and enable or disable performance profiling where you choose.

5 Below is an example of how the profiling API can used: Public static void CreateObjects (int p) { RedGate.Profiler.Api.Reset(); RedGate.Profiler.Api.Enable(); Hashtable ht = new Hashtable(); LinkedList<Object> 11 = new LinkedList<Object>(); ArrayList al = new ArrayList(); For (int i = 0; i < p; i++) { NClass1 newobj = new NClass1(); ht.add(newobj, null); 11.AddLast(newObj); a1.add(newobj); } GC.Collect(); } RedGate.Profiler.Api.TakeSnapshot(); RedGate.Profiler.Api.Disable(); By inserting the RedGate.Profiler.Api commands within your code as shown above, you will get just the results you need, and everything else will be ignored. Profiling earlier in the development phase When an application is first being written, the immediate focus is on the features, rather than the performance. Features need to be built, and good, sensible code written, in order to create those features and make them work. A general perception is that, once a feature is complete and covers the basics, the application can be optimized by tweaking elements of the code without wrecking any of the work already done. This perception is idealistic, and usually a long way from brutal reality. A developer will often have to rewrite large amounts of code, after discovering that parts of the code do not perform as well as expected. Then, of course, once the new pieces of code are created and tested, something else breaks and needs fixing. Code profiling three short weeks before shipping puts your whole project at risk. It leaves very little time to fix issues and, where it is deemed too risky to drastically optimize code at such a late stage, it greatly increases the likelihood that a poorly performing application will be released. When this happens, bosses, colleagues, and users, are quick to find fault. Reputations and, in extreme case, jobs, are unnecessarily put at risk. So, how do you minimize this risk? Profile your.net code early on during the development phase.

6 Code profiling after reaching any milestone (i.e. alpha, beta, final release) is essential. It gives developers the chance to catch performance issues much earlier, and to realize early on before anyone else notices if a piece of code has been badly implemented. At Red Gate Software, we use ANTS Profiler to profile our own products. In fact, ANTS Profiler was recently used, not only find out why a piece of software was performing poorly, but also to make a design choice, based on the performance-profiling results. Dan Archer is a key member of the Red Gate development team working on SQL Backup 5, Red Gate s desktop application for creating and securing SQL Server backups. His remarks, arising from his experience with ANTS Profiler during the development cycle, illustrate the case. "One of the most anticipated features of this new version is the timeline, which permits users to visualize their server s Backup and Restore history, current activity and future scheduled jobs." The timeline has quite a lot of work to do: fetching historical data from disk, calculating future job schedules based on job information retrieved from SQL Server, and monitoring current activity. Its graphical display naturally cannot synchronously perform these activities each time it has to be redrawn, since the display may be redrawn many times a second, as the user explores the timeline; so SQL Backup 5 has a system whereby items are fetched and cached on demand, and subsequently retrieved from the cache as and when they are needed. The caching system has to file and categorize items based on assorted criteria, and is an important subsystem of the timeline in itself. A lot of time was spent prototyping different caching approaches and trading them off against each other. Analyzing each prototype, Dan was surprised to discover that one of the largest performance hits in one candidate approach was a simple binary search. The complex and multilayered logic of the algorithm ran really quickly; memory allocation was, as can often be the case with.net, no overhead at all to speak of; but this binary chop was proving a bit of an issue due to the distribution of the data in question. "Fortunately, we had multiple approaches to hand, so the Profiler permitted us to make a design choice based on performance" stated Dan, adding "We also encountered a fairly trivial piece of 'Friday afternoon'code, whereby an O(n2) loop had crept into a trivial part of the caching system which, due to design changes, was now called rather frequently. ANTS Profiler was quick to point out the vast number of calls to the offending line, which was quickly and easily fixed." Conclusion A vital ingredient in turning a great app into a killer app is the decision when to start profiling your code after the first milestone, or just before the final release. With its line-level accuracy, ANTS Profiler Pro makes it significantly easier for busy developers to quickly identify performance bottlenecks..net code profiling can now become a stroll in the park, and developers can build highly optimized applications in far less time. For more information, and to download your 14-day free trial of ANTS Profiler Pro, visit Red Gate Software St John s Innovation Centre, Cowley Road, Cambridge, CB4 0WS, UK tel: +44 (0) toll-free: RED GATE ( ) sales@red-gate.com web: ingeniously simple tools