tutorial: heob (heap profiler; memory leak analysis)

Heob is an OSS project, short for ‘heap observer’.

How to configure and use?
0. The official documentation from Qt/QtCreator is – like always :’D – a bit sparse: https://doc.qt.io/qtcreator/creator-heob.html
1. Get it from: https://github.com/ssbssa/heob/releases (I’ll use here release 3.1 from July 2019) and extract to the directory of your choice. This directory has to be set later as configuration path.
If you use gcc/mingw, then make sure you’ve dwarf-stack enabled. Since I’m just using the MSVC, not much had to be done.
2. Inside QtCreator (I am using right now 4.12 from the Maintenance Installer) go to “Analyze > Heob” and configure it like this:

The floppydisk-icon can be saved to store ONE configuration.
I leave most of the time the tracing to simple, else time-critical processes can fail. The output-files should be named if you do several runs, which you want to compare or post-process. Most of the time it makes sense to start disabled, because else heob tracks already all the losses at start and this will delay the start.
3. As example, I’ve set Cullendula as UUT (unit under test).

Since heob was started disabled, the leak recording is off: Activate it by pressing ‘n’. If you resize the terminal, the last line can become invisible due to some glitch. So better leave the size of the window untouched!
4. Do your favorite workflow in the UUT. Then close/quit the UUT.
5. Depending on how much allocations were done, heob takes more (up to ten minutes!) or less time (seconds in the case of Cullendula) to evaluate the leaks.

The results are sorted in descending order. Expand the entries to check the stack-trace of the cause.
Some can be triggered by leaks in the underlying libraries (Qt .. I am lookin at you: https://bugreports.qt.io/browse/QTBUG-59621), some by your own buggy implementation.

Hint: the generated xml-report can be later loaded again in the results-tab. Or specify “-o leaks20200617.html” for an optically more pleasing result.