I dont know who did it first, but its certainly a useful alternative to instrumented profiling.Hes also enjoyed working with SVG, Java 3D, Java FX and Swing.Profiling Vs. Sampling in Javas VisualVM April 24, 2014 1 min read Most people will already be familiar with profiling, but you might be less aware of the different types of profilers on offer.A recent issue we had upon the release of Java 8 proved awkward to resolve using a traditional profiler, but Sampling proved well suited to the task.
Helpfully, Java comes with both a traditional profiler and a sampler in the form of VisualVM. Im just going to be talking about CPU profiling, although the approaches to memory are similar. VisualVMs Sampler and Profiler tabs VisualVMs profiler works by instrumenting all of the methods of your code. ![]() VisualVMs sampler, however, takes a dump of all of the threads of execution on a fairly regular basis, and uses this to work out how roughly how much CPU time each method spends. Java Cpu Profiler Software By RunningSo what was our problem with profiling We test our software by running our PDF to HTML5 converter on a large number of diverse PDF files which make use of different parts of the PDF specification and flagging up any changes in the output. One problem with instrumented profiling is that it adds a constant amount of extra execution time to every single method call. Sometimes such as in image processing small, quick methods are called many, many times, adding a great deal of time to the execution. Profiling our tests this way would take hours Sampling, however, takes a more or less constant amount of time each second to record stack traces for each thread. This only added 5 10 minutes of execution time in total, and still provided us with a good idea of where the problems lay. One quirk of sampling is that the number of invocations recorded is not necessarily accurate, since a short method could easily start and finish between stack dumps. It appeared as though a method in our library was called three times as often in Java 8 as it was in Java 7 the truth, however, is that it was taking three times as long, and thus was three times as likely to be caught in a dump. Perhaps the lesson here is that sampling is most useful for recording the amount of CPU time spent, rather than the number of invocations. Still, theres a very high chance that this will identify any problems, and do it much faster than the standard profiler. IDRsolutions develop a Java PDF library, a PDF forms to HTML5 converter, a PDF to HTML5 or SVG converter and a Java Image Library that doubles as an ImageIO replacement. On the blog our team post about anything interesting they learn about. Sam Howard Follow Sam is a developer at IDRsolutions who specialises in font rendering and conversion. Java Java visualvm Major change to Color performance in newer Java releases Blend modes in Java2D and JavaFX How does Java handle different Images and ColorSpaces Mark Stephens Jan 29, 2020 1 min read How does Java handle different Images and ColorSpaces Mark Stephens Jan 22, 2020 1 min read How does Java handle different Images and ColorSpaces Mark Stephens Jan 2, 2020 1 min read 8 Replies to Profiling Vs. Sampling in Javas VisualVM Prakash says: September 20, 2016 at 7:38 am Hello Sam, Very well said on above issue. ![]()
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