GitHub Git Merge 2022, 18 Oct 2022

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From YouTube: Git driven debugging - Git Merge 2022

Description

Presented by Rizel Scarlett, Junior Developer Advocate @ GitHub

Developers often debate using print statements or the debugger to trace bugs within their code. But what if I were to tell you that you can use Git? In this lightning talk, we'll explore using Git to quickly identify and resolve bugs and regressions.

About Git Merge:
Git Merge is dedicated to amplifying new voices in the Git community and showcasing the most thought-provoking projects from developers, maintainers, and teams around the world. Git Merge 2022 took place at Morgan Manufacturing in Chicago, IL on September 14th and 15th.

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Cool hello, everybody. um Today we are going to talk about git, driven debugging and I'm gonna ask for.

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Like a little bit of audience, interaction, because that makes me feel more relaxed.

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um So I have a question for y'all and you don't have to yell it out. I'm gonna let y'all do like.

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Indicators, what is your favorite method for debugging and I'm gonna give you two choices. Do.

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You prefer using the debugger, or do you prefer using print statements if you prefer using the.

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Debugger do like a heart hand, all right. We got a couple. Cool cool cool, all right, see one over.

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There and over there all right and then for people who, like using print statements, do this.

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Yeah, all right cool, all right, I'll, tell y'all what my favorite is. I mean. Maybe nobody cares.

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But I'ma share it anyways, so I prefer print statements 20, because I'm a little bit lazy.

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As a developer, but the other 80 is, I don't think the buggers like me, I swear it. Doesn't.

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Matter what company or project I'm working in my debugger is always broken, and then I have to.

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Like edit the launch.json file and then I feel like I'm just debugging my debugger, so I could.

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Debug my code and it feels really inefficient. However, I do like see the value of it um when I'm.

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Dealing with like race condition, issues or state management issues, so it has been helpful there.

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um But we're not really here to talk about like print statements versus the debugger.

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um I'm actually here to introduce you or reintroduce you to a faster way to identify.

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And resolve regressions using it. I thought it was going to be like the first person to talk.

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About that at this conference, but I've heard like more than one person talk about this already so.

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um But it's called get bisect and we're going to go into it a little bit deeper, but first.

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I'm going to introduce myself to y'all because you're probably like who's this.

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Amazing person on the stage, um so my name is roselle. I'm a junior developer advocate.

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At github prior to working at github, I was a software engineer for about three years.

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um I'm currently an advisor, and I was a director at g-code house, which is an organization that.

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Teaches women of color and non-binary people of color about web development, I'm pretty passionate.

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About like empowering and educating people about tech, but I'm also passionate about using social.

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Media, some might say, I'm like a little addicted to twitter, but you know um so if you also use social.

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Media you can go ahead and follow me at black girl bites. uh That's my handle on twitter on hashnode.

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And dev.2 I write a lot of blog posts on github on instagram youtube whatever, um but on twitch.

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And black girl bites one because I forgot my password and got myself locked out of my account.

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So I only have a little bit of time here, so this is the agenda. We're going to talk about how I.

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Discovered git bisect what it is and how to use it, and then I will wrap up. So I discovered it while.

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Working at a startup that was this started was a little bit toxic, but I will give it to the startup.

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I learned so many things like that. A junior engineer probably wouldn't be getting a lot of.

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Experience with I learned about like dynamodb and cloud watch and cloud formation and twilio, and I.

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Learned a lot about git and prior to that startup. I really was kind of scared of git and github. It.

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um So I went to coding bootcamp, I attended a coding boot camp and I was very confused by.

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All of it, so I was like I'm just gonna memorize, these four commands, and hopefully that will get.

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Me through life I was like all I need to know- is git init,, git add, git commit, git push. I didn't.

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Even know how to do pull requests, um instead of like doing a pull request, I would just delete.

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The whole repo edit it locally and then push it back up, because I was scared to break something.

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um But after that boot camp I went to internship and we were using mercurial. So I forgot everything.

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About git, um but then I started out this startup and I met my co-worker called the get tater you.

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Would think it's like I'm I'm bullying him or something, but he liked that name like that was a.

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Name that he coined for himself, um and he saw that our our team- our company, was not using a great git.

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Workflow, so he really got us together. He taught me how to rebase. He would sit down with me every.

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Time I needed to rebase and start yelling at me. He's like no don't do that. Do this, I'm like okay,.

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Got you and then um he also introduced me to git bisect and you're? Probably like you, keep talking.

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About git bisect, what is it um so git bisect to me is one of the secret ways to faster debugging. The.

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Way it works, is it's powered by a binary search algorithm and it searches through your project's.

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Commit history to identify when a bug was first introduced, so what it needs from you is for you.

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To give it a good commit or a moment in time, when the bug wasn't present and then a bad commit on a.

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Moment in time, when you did see the book and what it'll do is it'll go through those those.

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That range you gave it and it'll find when it was initially introduced, but please note for it.

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To work well, you do have to have a linear commit history, because, if not, that doesn't really reflect.

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The true changes that were made in your code and it can get git bisect a little bit confused.

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So you might be thinking. Why would I need to get to go through my commit history? I can do that.

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Myself, I can do it manually, but if you think about it, why not expend way less brain power? Finding the.

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Book and spend more brain power actually fixing it. Also, if you have a project where there's like a.

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Large number of commits doing a linear search can take forever right, like just imagine, going one by.

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One by one, that's like a lot of work, but what git bisect is doing is using a binary search, algorithm.

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So basically, it's going to reduce the number of revisions that are potentially bad by half.

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So, oh I forgot about this slide, but basically this is a gif. If people are not familiar with a binary.

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Search algorithm, the hot top half of the gif shows that a binary search algorithm can find the number.

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37 in like three steps, whereas in a sequential or linear search when you're going one by one by one.

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It takes it takes about 11 steps, so there you can see like the how much more efficient it is.

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And then here's like a little visualization how git bisect will work is like you'll give.

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It your good commit and a bad commit and it'll go through each of them and be like. Is this one? The.

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Bad commit and you'll be like not really and then it'll take off, though all the ones in between and.

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Ignore those and then it'll try to identify the other ones it hasn't checked. So that might not.

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Have made sense so I made a demo and I'm not going to do it live. I have a video because the demo gods.

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Are never with me, so let's just go with this video all right so um before I start it because I move.

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Really fast in this video is I'm going to open up my repository and github code spaces if people.

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Don't know what github code spaces is. It allows you to use visual studio code in your browser.

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It also comes with a terminal, it's not the same thing as when you press dot in your repo everybody.

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Gets confused with that? That's like github's web editor, but basically I'm going to press it.

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um And I'm showing y'all, but the cool thing too is that when I loaded up my this code space, I got.

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It to have everything I wanted, including extensions, because I use this repository.

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To teach people front-end web development and I want them to have all the extensions.

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um Necessary, so I'm just showing you that I made a dev container.json to make sure my dev.

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Environment was right and eslint um is already installed, along with the other extensions, but.

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Look at the bug on in this video. Let me pause it really quickly, but the bug is this: clock is.

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Moving like irrationally fast and I'm like, I don't know why, when did I mess this up so.

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What I'm going to do is use git bisect to help me out and I'm going to type git. Bisect start.

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So I'm typing git bisect start and then what it's going to do is ask me for a.

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Good commit and bad commit, so I'm going to look through my git log and I'm like.

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um The bug is present in this current commit, I see so I'm just going to take the most recent one. So.

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I type git bisect bad and I put um paste in that commit hash and then for the good commit I'm going.

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To look through my git log again and I'm like I don't remember it existing when I added a red.

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Background so I go ahead and do git bisect good, and I paste that that actual commit hash in there.

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And then it gives me, let me pause it real quick. It gives me.

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um A commit hash that it possibly could have been introduced in so I'm going to go ahead and check.

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That one out and I think in this video I realized I didn't- need to copy the whole long like hash. I.

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Just needed the first couple numbers, so I'm going to go back to my editor and copy the right part.

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And then I'm gonna go to it, and this is definitely not where the bug was introduced. Let me I wish.

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I could rewind it a little bit: it's just yeah, it's not where the bug was introduced because.

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This is just some html that I changed, so I'm going to go back to git bisect and tell it nah.

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That's a bad commit, so I'm going back and I go git bisect bad and it suggests another one for.

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Me- and it says we have no other choices like there's, roughly zero steps left. This has to be.

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It so I go ahead and I copy that commit hash, and hopefully this is it so we're gonna see. I.

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Look through my commit history again I find that hash, and that is definitely it because for some.

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Reason I changed the word hour to seconds so now my hour hand is moving as fast as.

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My second hand, so what I'm going to do is go back to my code in my script.javascript file.

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And change that to say hour instead of seconds and now my clock is moving like a normal clock.

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Cool, so going back to this and we're basically wrapping up is oh.

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I am super excited. I just want to end with saying I'm super excited for the direction that.

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Developer tools are going in to make debugging easier. There's projects like replay io that.

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um Enables us to have a time, travel, debugger and all these other things that make developing.

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Easier every time I listen to somebody talk about like when they were coding back in the.

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Day, like I was listening to martin the other day, saying like oh, he used to what was the.

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He used to do print out the the git revisions that sounded crazy or, like the version control.

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And highlight it: that's that's really wild that that happened, um but I'm super excited to see.

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This landscape grow and make things a little bit easier for us. That's all I have thank you. Everyone.