Re: How to debug python blocks.

[Marcus Müller]

What I've *done* in the past, but I can't remember how pretty that was:

GDB has python integration (essentially, a large gdb script + python debug 
infos). If you
can break at a C++ function that your python work() calls, you should be able 
to e.g.
py-bt into the mother frames etc.

Cheers,
Marcus

On 17.01.21 22:52, Jeff Long wrote:
> Yah, there might be some kind of hack, but you're right ... since a Python 
> block is being
> exec'd via a C++-to-Python gateway it's in a no man's land from the debugger 
> perspective.
> 
> On Sun, Jan 17, 2021 at 4:46 PM Nicholas Long <nicholaslong94@gmail.com
> <mailto:nicholaslong94@gmail.com>> wrote:
> 
>     So I get the fact that GNURadio is highly parallel, that is fine. I debug 
> C++ OOT
>     blocks all the time and it is super easy, generally I make specific 
> effort to isolate
>     the OOT block that I am currently working on in a test flowgraph.
> 
>     For C++ OOT blocks I just run the python top_block.py in gdb (via 
> vscode), and place a
>     breakpoint in my C++ OOT block, and it works.
> 
>     If I want to debug the python flowgraph, (generated from GRC or custom), 
> I can do that
>     via the python debug tool, I cannot step through the internals of blocks, 
> but can see
>     if things are hooking up correctly.
> 
>     my problem, (and I personally don't think that there is a solution, but 
> am happy to be
>     wrong) is that there is no way to place a breakpoint inside a python 
> block, like I do
>     in the c++ blocks. presumably the swig (I'm still on 3.8) process removes 
> all the
>     information?.
> 
>     As for specific use cases, the more complex blocks I write are all C++, 
> but sometimes
>     it is useful to write a quick and dirty python block which I can then use 
> for
>     debugging purposes. However when I do this I have to resort to using 
> print statements
>     to make sure everything is working like I expect. It's ok and workable, 
> but I am not
>     that good of a programmer and tend to do guess and check, which a 
> debugger, rather
>     than adding/removing print statements really speeds up. 
> 
>     So I guess there is nothing in particular to debug, but If there is a 
> more efficient
>     way to work I would love to know.
> 
>     Nick
> 
>     On Sat, Jan 16, 2021 PM Jeff Long  wrote:
> 
>         Python includes a debugger (pdb) and IDEs like VSCode have decent 
> Python
>         debugging. This should work fine for Python scripts like those 
> generated by GRC.
>         Internally, GNU Radio is highly parallel, which creates additional 
> challenges not
>         related to language ... how do you stop one block when that changes 
> the behavior
>         of, or crashes, the whole framework?
> 
>         Anything in particular you are trying to debug?
> 
>         On Sat, Jan 16, 2021 at 6:51 PM Nicholas Long 
> <nicholaslong94@gmail.com
>         <mailto:nicholaslong94@gmail.com>> wrote:
> 
>             So this is a relatively generic question about what people's 
> processes for
>             writing and debugging python blocks are. 
> 
>             In C++ I use VScode and just run the gdb debugger - I can place 
> breakpoints,
>             look at variables, and step through the program super easily. 
> 
>             Ideally I would like to be able to do the same with python 
> blocks, but am not
>             sure if it is possible.
> 
>             Thanks, 
>             Nick
>