Stopping ipdb debugging in Jupyter

Question

I am using Jupiter and trying to learn how to debug. However, I cannot complete exit from the debugging mode.

for i in np.arange(1,10, 0.01):
    a = someFunc(i)
    # I want to check the value of "a" in each iteration
    # here!
    from IPython.core.debugger import Tracer; Tracer()() #this one triggers the debugger

If I run this code and type "q" or "exit" in the debugging ipdb prompt, it just keeps running the code until the next break point, and I cannot stop debugging. How can I stop debugging? I looked into the documentation, but could not find any other command than "q".

mikitk · Accepted Answer · 2016-10-24 08:15:52Z

3

You need to start tracing before you enter the loop. What happens currently is that you create a new debugger instance with every loop step.

You code would look like this:

from IPython.core.debugger import Tracer

for i in np.arange(1,10, 0.01):
    a = someFunc(i)
    Tracer()()

You will get a command line prompt where all standard ipdb functions can be used. By calling Tracer right after you execute someFunc(i) you will get a new prompt with every iteration. To continue execution until the next iteration use c command. To set breakpoints use b <line number>. q will stop execution all together.

edited Oct 24, 2016 at 8:15

answered Oct 23, 2016 at 7:27

mikitk

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5 Comments

noclew Over a year ago

Thanks miktik. Then, if I want to check the value of 'a' inside of the loop as above, how can I set the breakpoint inside of the for-loop?

mikitk Over a year ago

Tracer()() acts as a breakpoint, you can put it right before or after the line you want to check. I've updated my answer, hope it helps (please accept the answer if it does).

noclew Over a year ago

Thanks for the update. However, if I run the code above, I still cannot exit from the loop by typing "q". For example, if I type "q" in one iteration, I just get to the next iteration, meaning that I have to press "q" 1000 times to exit the loop. Is there anyway to get out from the loop when the break point is inserted in the loop?

mikitk Over a year ago

Interesting. For me, if Tracer is imported outside of the loop and initialized inside the loop, q quits the debugger and breaks the loop execution

noclew Over a year ago

hmmmmm... this is really annoying :(

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