This page gives an overview on how to debug GRAMPS.
When a hard crash occurs, you typically have no idea where the crash occurs. It is important to know the line where the crash occurs. So if you are able to reproduce the crash, restart GRAMPS with the command:
python -m trace -t src/gramps.py
Add debug statements
GRAMPS is run with the optimize flag.
python -O gramps.py
This gives you the option of adding debug statements. You can use the __debug__ variable or the assert statement for this. This allows us to add code to GRAMPS that will be printed out when GRAMPS runs without the optimize flag:
More info: 
Use the log infrastructure
GRAMPS has built in the python log infratructure. GRAMPS runs with logging level logging.DEBUG to stderrh.
More info: Logging system
Short: in your code add data to the logger with: log.warning(), log.error(), log.info()... Start Gramps with the --debug flag: pyhon gramps.py --debug="name_of_the_logger"
This is usefull when working in different parts, adding info output, and selecting on the commandline with --debug the logger you want to see output with.
GRAMPS has a convenience hook to allow you to do profiling. Profiling gives an overview how many times methods are called in a code fragment and how long each one took. It helps to find perfermance bottlenecks.
An example usage:
Add at the top of the file you want to use profiling:
from Utils import profile
Then, suppose you want to profile a save function on one of the editors. The save is called due to a connect done in the method _connect_signals. So, change the connect to save to a new method testsave you make:
#self.define_ok_button(self.top.get_widget("ok"), self.save) self.define_ok_button(self.top.get_widget("ok"), self.testsave)
Now add the testsave function as follows, where you use the profile convenience function:
def testsave(self, *obj): profile(self.save, *obj)
Then run gramps, everytime you save, the profiler kicks in and prints to command line a report with the time for each function.
So in short: replace the call to a function/method to calling profile with as first parameter the function/method, and other parameters the parameters of the function/method.