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Ask HN: How do you get better at debugging/finding a solution?

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Ask HN: How do you get better at debugging/finding a solution?

#1

Post by recvonline »

Software dev with more than 10 years of experience. I always gotten praise by colleagues and companies I worked for. But, there are always moments where, without help from a colleague, I wouldn't have found a solution to a problem.

When joining a new company, 2 months in, and facing a problem where code wouldn't compile, I dig deep into the codebase but for the love of me, can't find a solution.

I wonder, is that normal? Or how can I say: "I don't care, if I am alone, I can figure this out and solve it."

Did anyone here evolve from this state of reliance of others and turned themselves into a "I can do it myself in a good amount of time"?

Re: Ask HN: How do you get better at debugging/finding a solution?

#2

Post by groffee »

It's probably not so much your colleague that helps but the act of just talking through a problem, inanimate objects work too https://en.wikipedia.org/wiki/Rubber_duck_debugging

What also helps is just shutting the computer off and going for a walk, generally the moment you step away you'll figure it out!

Re: Ask HN: How do you get better at debugging/finding a solution?

#4

Post by Fnoord »

groffee wrote: post #2

It's probably not so much your colleague that helps but the act of just talking through a problem, inanimate objects work too https://en.wikipedia.org/wiki/Rubber_duck_debugging What also helps is just shutting the computer off and going for a walk, generally the moment you step away you'll figure it out!

> What also helps is just shutting the computer off and going for a walk, generally the moment you step away you'll figure it out!

Underrated. Diffused mode of brain.

Re: Ask HN: How do you get better at debugging/finding a solution?

#5

Post by ramesh31 »

The most important thing I’ve learned as a dev is to be comfortable in a space I know nothing about, and to have the confidence to know “I know nothing now, but I will eventually reach the solution and fully understand it”. It’s a process. You start out groping blindly in the dark for a handhold. When you find the first one, suddenly others start falling into place. Then there’s a tiny pinhole of light that you start working towards. And all of a sudden you’re in full daylight, striding from ledge to ledge fearlessly. It’s the most beautiful thing about programming; to do this over and over again.

Re: Ask HN: How do you get better at debugging/finding a solution?

#6

Post by andrewstuart »

I've mostly worked alone as a developer. No-one is going to fix it but me.

Actually I think I enjoy problem solving more than the actual programming. Though frankly programming and problem solving are so closely related they are almost the same thing.

I can solve most problems I come up against day to day. I guess I can't solve them all because I do ask questions on Stack Overflow sometimes.

I'm not sure why, I guess it's a few things:

1: As I said, I enjoy problem solving - it feels like a game

2: I have more than 35 years hard computer problem solving, so there's alot of experience which helps.

3: I understand, and make a deliberate effort to understand, as much as I possibly can about every aspect of computer systems from hardware to operating system to database, to cloud to front end to back end.

4: I use the tried and tested problem solving method of divide and conquer - when you have a problem, break the software in half and keep doing so until you find where the problem is.

5: If you are still stuck, try to create a minimal test case the demonstrates the problem - this often solves it, and if it doesn't then you can post the minimal test case on StackOverflow.

6: Only ever work on one thing at a time.

7: Work hard to learn how to use problem solving tools.... the debugger in the browser, make sure you know a little strace for doing things like tracking what file the operating system is trying to open, ngrep so you can watch data passing over the network.

8: Be relentless. Sometimes I think this is a personality "issue", but I literally will work for 10 hours at a time trying to solve a problem until I crack it. I really don't like finishing work without having all the days problems solved. I just grind and grind and grind on problems until I work it out.

9: Have a really thorough knowledge of the technologies you are working with - don't be satisfied with learning as you go - actually take the time to read the language specification for the languages you program with, stuff like that.

10: Use a really good IDE and make sure you know how to use its ability to jump through the code, to jump to function definitions. You need to be good at following the logic of the program.

11: And finally, if no matter what you do the error remains the same, then you are probably not even working on the correct code.

In the case for example of why a program won't compile, well just start cutting code out until something compiles, then add it back in little by little until you work out where the line is that fails. Even better is to use appropriate debugging tools, but divide and conquer always works.

There's also no shame in scattering these everywhere you suspect the problem might be:

print('got here!')

Re: Ask HN: How do you get better at debugging/finding a solution?

#7

Post by samuell »

I have often found myself being able to dig forward way after many of my peers (not all) are out of ideas. I have seen a shift in my own ability to debug problems after I realized that with increasing "hardness" of the bug, you need to just increase the level of systematicness and rigor of your method.

The very first thing should probably be to carefully check which commit introduced the error, and then carefully study the code changes in that one for clcues.

After that, and possibly based on that, what probably most people will do is start their debugging process by running a debugger through some suspicious parts of the code, based on varying degrees of well-informed suggestions.

For problems that escape those first tries though, what you often need to do is to start a systematic process of ruling out possible sources for the bug. In many ways this resembles scientific studies where you try to control as many variables as possible, and also include control samples with known states, trying to zoom in on only the particular variable you are studying without noise from other things.

That can mean feeding the system or code under study with carefully set up data for which you know what the effect should be, and then carefully trying to change each part of it and observing the outcomes. Things like that.

In my experience, this type of effort will eventually most often lead to the solution. The main challenge I think though, is to realize how deeply you might need to go with the systematization and automation of things, to really rule out possible sources and start zooming in on the general area around where the bug is. You might need to take some real drastic measures, and this is where I see most people who fail, don't go far enough. Here you might need to really get away from the screen to get your thoughts flowing more freely ... but not in an undirected way, but rather trying to answer the question "How can I do this in an even more systematic way ... to rule out even more possible sources, or identify unexpected behavior".

Not super easy to put into words, but this is in my experience the way to go.

Finally, one caveat is that there are certain things you should probably check before even going the systematic path. Things that can totally screw things up so that whatever you do, you never get any systematic pattern of behavior or behavior change. These things often are related to caches in various form. Make sure to turn off any and all kinds of caches in the system. They will almost guaranteed drive you insane otherwise.

Re: Ask HN: How do you get better at debugging/finding a solution?

#8

Post by nicbou »

groffee wrote: post #2

It's probably not so much your colleague that helps but the act of just talking through a problem, inanimate objects work too https://en.wikipedia.org/wiki/Rubber_duck_debugging What also helps is just shutting the computer off and going for a walk, generally the moment you step away you'll figure it out!

If rubber ducking fails, try to write a GitHub issue that starts with "it's probably my fault, but".

By the time you're done describing the problem and its symptoms, you'll have a solution.

I can also recommend going for a walk. I usually return from long motorcycle trips with the best ideas. Tea on the balcony is also effective.

Re: Ask HN: How do you get better at debugging/finding a solution?

#9

Post by xyzzy4747 »

If you can’t figure out a problem, just go back to the basics.

Comment out or delete the code until the fundamentals of the system works. Then add stuff back until errors happen. Also add better logging to track down the problem. Tear down the system and build it back up. Delete nonstandard approaches you can’t figure out and use standard ones from QuickStart tutorials. It might be slow progress but progress will be made.

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