Hacker News Reader

Comment by hinkley | Hacker News Reader

Pair debugging is an exercise in patience that I often lose.

If I had a dollar for every time I asked someone "Okay, look for other uses of this variable" and they grab the mouse and stare at the screen because THEY'RE READING THE ENTIRE FILE LOOKING FOR A PIECE OF TEXT, instead of using any of the dozens of search mechanisms at their disposal, I could retire and write self-help books for programmers.

Stop trying to white-knuckle everything all the time, you masochistic people. Use tools like a sentient creature is supposed to.

View on HN

Maybe the other person in the pair is forgetting to use their tools because they are stressed out by the aggressive person standing over their shoulder looking for any excuse to grab the keyboard?

Sometimes, this might be the case, however after the nth time of nicely saying "oh btw you can just do [insert shortcut] and find it right away!" it's hard to not get frustrated. I have definitely worked with people who for whatever reason, absolutely refuse to learn their text editors and debugging aids.

Usually this becomes an interpersonal issue when you're working with someone who has a track record of only changing 90% of the code that needs to be changed to implement a feature/bug fix because they keep missing one spot where the information is used.

cough I have no idea what you're talking about.

Mostly I think the exploratory phase of debugging is a battle between your limited short term memory and your imagination. It's a think you need to do alone and without someone stopping you to ask why every fifteen seconds. I think that's why people are so big on repro steps, so they can go off and start the process of elimination without having to dump state while defending checking possibility A before checking possibility B.

I think the only reason (besides tenacity) that I fix bugs that others gave up on is that I have tricks that let me walk the code faster, which lets me make forward progress on deduction before I forget WHY I was looking under this rock in the first place. My debugging practices look not unlike a guy looking for his missing keys. You have to be careful about when to hit him for questions, and most of the time it's better to just start your own parallel search if you want to help.

> which lets me make forward progress on deduction before I forget WHY I was looking under this rock in the first place.

There's nothing quite as deflating as finally getting to the end of diagnosing a particularly pernicious bug just to have the understanding trigger the realization that you've encountered this bug before a year or two prior, spent just as much time originally figuring it out, and had somehow forgotten about it the interim. Yay for wasted days of our lives.

Whenever I unravel a hard-to-diagnose bug, my first step is always to put a better error message in the place where it would have been properly diagnosed.

Sure. I can't recall the last bug that brought this feeling (sigh, the circle continues), but I vaguely recall it being a weird interaction or behavior when interacting with some remote system, and it wasn't in fixing a bug that popped up, but in implementing a new feature or system that interacted in a similar way, but the prior implementation was either in a different project or had since been discarded. I know that's vague. That probably means I'll encounter this again and not identify it as the same problem. :/

I think I need to make a concerted effort to get more sleep.

// Increment this number every time you end up here

// time spent = 30

If you haven't recognized your "old bug friend" during the figuring-out process, maybe the path that lead to the bug was different this time? I.e. you have an old bug in a new context, which is almost like a fresh new bug.

Personally, when I find out / solve something tricky I note down the details in a notes file exactly for cases like this. I'm yet to use it though, because I usually remember the weirder bugs I've seen.

I'm pretty sure it was. From what little I remember of it now, I think it was probably best classed as "weird and esoteric undocumented or wrong behavior in a remote system or API".

Are you willing to share your tricks publicly?

Yeah, it's not that. Lots of programmers inherently don't use the tools at their disposal... something which also shows on the code they right...

Maybe tooling doesn't always go deep enough where it matters. For example, your spell checker didn't help you at all in that last sentence.

I didn't use it, which further proves my point!

How would it have? What you have isn't a spelling error, it's a grammatical/word choice error.

Spell checkers also have grammar checking modes...

Assuming you mean right/write, it would need to be a grammar checker, and a damned good one at that.

Or just one that uses statistical probabilities...

A good example, graphical debuggers.

Already in late 90's I couldn't believe what UNIX coders considered state of art, versus what we had on Mac/Windows/Amiga environments (the ones I knew before UNIX).

Maybe sometimes. I've certainly worked with someone who explicitly said "if your first instinct on seeing an error is to reach for a debugger you're probably not a good programmer", and as a result he'd spend hours tracking down a bug that could be solved in minutes by someone willing to actually use tools. Even more unfortunately, a lot of the junior programmers on the project listened to him and wouldn't use debuggers either.

It's your fault for saying "look for". They're doing just that. They're using all their available brain power thinking about the code so they don't have any to spare to interpret unclear instructions. Instead say "search for", or if that's still unclear say "control-F for" (or whatever shortcut activates search).

Have you tried suggesting that exact trick (using search rather than scanning) to your pair whenever they default to the Mark One Eyeball?

Having paired quite a bit, it's rather amazing how many programmers just don't know the full utility of their existing tooling. Not because they are stupid, but just because they never made that particular connection.

I have been on the receiving end of this dozens of times, and it is one of my favorite things about pairing as a programmer: where my pair shares a neat trick that saves me a notable amount of time and/or aggravation.

Reply on news.ycombinator.com