[Python-Dev] short-circuiting runtime errors/exceptions in python debugger. (original) (raw)

Nathaniel Smith njs at pobox.com
Mon Oct 29 20:09:22 EDT 2018

On Mon, Oct 29, 2018 at 11:59 AM, Chris Jerdonek <chris.jerdonek at gmail.com> wrote:

A simpler feature that could possibly help him (assuming there isn't any external state to deal with) would be the ability to save everything at a certain point in time, and then resume it later. He could rig things up to save the state e.g. after every hour: 1 hour, 2 hours, etc. Then if an error occurs after 2.5 hours, he could at least start resuming after 2 hours. This could be viewed as a cheap form of a reverse debugger, because a reverse debugger has to save the state at every point in time, not just at a few select points.

That's very difficult to implement without help from the operating system, but there is prior art...

On Unix, you can use fork() as a hacky way to do this – fork() off a process every once and a while, and have the children enter some kind of loop waiting for instructions (continue / enter debugger / exit / ...).

Or, on Linux, there's: https://www.criu.org/

I also wonder if it would be useful to give pdb the ability to break when an exception is raised, rather than when it's caught?

-n

-- Nathaniel J. Smith -- https://vorpus.org

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