In 2019, I optimized QStringList::removeDuplicates() by using std::pmp::unordered_set with a std::pmr::monotonic_buffer_resource, when available. The class that I wrote to encapsulate this optimization has since been re-implemented three times. The latest iteration has recently landed in KDToolBox. If you have code that looks a bit like this: then you should read on. Before my change, the […]

Some time ago, I noticed that a unit test was quite slow, using 100% CPU for a number of seconds at one point in the test. I used perf and KDAB's Hotspot to record and examine where the CPU cycles were spent in that unit test, and I quickly noticed that a lot of time […]

Note: This is the English translation of the article first published in German Intro The ESE Congress is one of the lead events for Embedded Software Engineering in Germany. This year it was held digitally for the first time, so that participation was also possible via video. Over five days, there were 3 keynotes and […]

For many developers, QNX is the operating system of choice, when it comes to developing on embedded systems. However, the performance limits are exceeded quickly, especially if you're working on low-end hardware. As a result, you'll likely need to perform an investigation to find the bottlenecks that contribute to reaching these limits, in order to […]

Another day, another blog post about KDToolBox, KDAB's collection of miscellaneous useful C++ classes and stuff. Today, we'll talk about ways to throttle your signal/slots connections -- in other words, how to activate a slot less often than the emission rate of the signal it's connected to. The usual reason why you may want something […]

A long time ago, I wrote a post about creating custom shapes in Qt Quick, via the scene-graph APIs. That post covered defining suitable geometry to draw a part of a circle, known also as a 'sector', efficiently, since such sectors occur commonly in instrument and vehicle interfaces. I started writing the second part, about […]

This is the third and last installment of our series about full stack tracing. If you haven’t read them yet, you’ll probably want to check out the introduction and tool setup portions first. In this blog, we’re going to focus on visualizing and interpreting full stack traces. At this point, we’re going to assume that […]

Some time ago, I wrote about how to build C++ projects with ASAN on Windows. Now, if you happen to deal with Qt projects you may want to take this one step further and sanitize Qt itself. Why bother with a sanitized Qt build? Let's have a closer look on why having a sanitized Qt […]

Wait, there’s more? Yes, indeed. Qt Desktop Days delivered a lot of great content we’ve just got to share. VLC and Qt, a history If you need to play the widest variety of audio, video, or streaming formats on the planet, you probably know about VLC (the “cone player”). But did you know that VLC […]

If you’ve read the first article in this series, you’ll know what full stack tracing is and why you definitely want it. This time, we’ll show you how to setup full stack tracing on your Linux system. There are two steps – first get everything configured to capture a trace, and then view and interpret […]

A few days ago, a customer using our KD Soap library reported an interesting problem with it. The library worked perfectly to access the SOAP server, but there was some noticeable latency when doing a series of requests in short succession from the client. This latency should not have been there, as both the server […]

Full stack tracing is a tool that should be part of every software engineer’s toolkit. It's the best way to investigate and solve certain classes of hard problems in optimization and debugging. Because of the power and capability it gives the developer, we’ll be writing a series of blogs about it: when to use it, […]

GammaRay 2.11.2 We have released version 2.11.2 of our Qt application introspection tool GammaRay, bringing support for Qt 5.15 and improved Qt Quick item picking. GammaRay is a software introspection tool for Qt applications developed by KDAB. Leveraging the QObject introspection mechanism it allows you to observe and manipulate your application at runtime. This works […]

Memory bugs are tricky. Leaks have a clear impact on performance, and quickly become hard to spot when heap allocated objects move too much. Memory access bugs, on the other hand, make your program crash right away, if you're lucky. In less desirable cases, they may end up corrupting random objects on the heap, and […]

What is Akademy? Akademy is the yearly conference for the KDE community, which is a community devoted to creating free software for desktop and mobile. Typically, Akademy takes place in a different city each year. However, due to the pandemic, the conference was online this time around. September 4-11 marked the dates of Akademy 2020. […]

We have just released version 1.2.0 of Heaptrack, the fast heap memory profiler for C++/Linux applications. A bit of Background The Heaptrack fast heap memory profiler allows you to track all heap memory allocations at run-time. Afterwards, you can use the accompanying GUI tool to find optimization opportunities in your code by analyzing the recorded […]

We are pleased to announce a new release of our Hotspot Linux perf performance analysis GUI, Hotspot version 1.3.0! Hotspot is a replacement for perf reportthat takes a perf.data file, parses and evaluates its contents, and then displays the result in a graphical form. You can read a bit more about Hotspot here. Overview of […]

After four months of intensive development work, I am happy to announce that the first QStringTokenizer commits have landed in what will eventually become Qt 6.0. The docs should show up, soon. While the version in Qt will be Qt 6-only, KDAB will release this tool for Qt 5 as part of its KDToolBox productivity […]

In the last blog post we saw an essential, C++ oriented, Visual Studio Code setup. That was enough to get going right away, but we can still definitely do more and better. Here I'll show you how to get a complete setup for your qmake and CMake projects, all this while also wearing a Qt […]

Part 2 If you are here from Part 1, welcome back. If you are wondering why we started at Part 2, go to Part 1. So, you tried everything from the first part (that was relative to you), and your screen is still a backlighting test? No problem. (Well.. I mean, clearly there is but […]