Debugging

At some point you will be writing code that does not work as expected. This is a normal part of the development process. The following sections provide some tips on how to debug your code.

Tracing

The tracing system is a powerful tool for debugging. It allows you to trace the execution of your code and see what is happening at each step, with minimal effort from the developer. You can use the tracing system to see what functions are being called, what arguments are being passed, and what values are being returned. You can also use the tracing system to see what messages are being sent and received. See Tracing in Erlang with dbg.

Debugger

Debugger is a graphical user interface for the Erlang interpreter, which can be used for debugging and testing of Erlang programs. For example, breakpoints can be set, code can be single-stepped, and variable values can be displayed and changed. Modules that will be debugged should be compiled with debug_info. See Debugger for Erlang.

Print debugging

While dbg offers powerful and fine-grained tracing capabilities, sometimes a simpler "printf debugging" approach is sufficient. This involves strategically inserting io:format/2 or io:format/3 statements into your code to observe variable values or execution flow. Remember to clean up your io:format statements once debugging is complete, or transition them to logger calls if the information is valuable for ongoing diagnostics.