Debugging

Some useful tips for debugging a recipe or the framework itself:

• when developing code for a transform or debugging errors, it can be really useful to start an interactive console by adding:

  start_ipython_dbg_cmdline(user_ns=locals())
  

  into the code in the recipe and running single-threaded by adding --worker 1 --single-threaded to the command line. This also allows modifying data and plots on the fly and continue the normal program flow afterwards.

• alternatively, one can insert a start_debug() at the desired breakpoint. This will drop into a ipdb debugger session, which allows traversing the stack of the interpreter. The program flow can be continued with a continue command. Unfortunately, code contained in a extra_code parameter is not visible in source form.

• alternatively, one can just raise an exception and it will be caught by the top level exception handler in run_recipe.py and then drop into an ipdb debugger session if the --debug flag has been set. It is also necessary to set --single-threaded, otherwise the data and other worker/thread-local variables are not accessible.