Debugging

How to debug and profile Qman.

Debugger

Use gdb (standalone or integrated with your editor/IDE).

To make sure the program gets fully rebuilt between debug sessions, use:

meson compile --clean && meson compile

Memory leaks

Test for memory leaks using:

valgrind --leak-check=full --show-leak-kinds=all --show-reachable=no --track-origins=yes --log-file=valgrind.out ./qman <arguments>

Then, examine valgrind.out.

Reports of lost memory that has been allocated by initscr() and doupdate_sp() can safely be ignored. They are caused by ncurses, which has a tendency not to fully deallocate its own memory.

For more granularity, we may want to pass --show-reachable=yes to valgrind. This, however, will result in even more spurious errors caused by ncurses.

Profiling

Use the following command:

valgrind --tool=callgrind --dump-instr=yes --simulate-cache=yes --collect-jumps=yes ./qman <arguments>

This will produce a file named callgrind.out.<pid> where <pid> is the process ID assigned to valgrind by the O/S. Use kcachegrind to open this file for further examination.

Debug logging

Developers can use function loggit() or macro logprintf(), both in util.h, to print messages to ./qman.log during development.

All calls to loggit() and logprintf() must be removed before committing to either main or devel.