My Problem with Git: No Abstraction

Git is powerful, and Github is its killer app. I use them for all my projects. That being said,

Git is more difficult than it ought to be, but until now I couldn’t put my finger on why

I was doing some mundane Linux command line work when I had my flash of insight. I’ve been using Linux for years, but I almost made a typical newbie mistake with the mv command. I wanted to rename a file:

mv /path/to/old_name new_name

Urp! I stopped, because this would not have just renamed the file, but moved it into my current directory as well. And then I recalled the typical mv tutorials which usually explain how the unix filesystem works, and how with that understanding, mv’s behavior makes sense.

In other words, mv combines two conceptual functions into one thing, simply because that’s the underlying implementation.

And I realized that this kind of “implementation leakage” occurs with many git commands. The non plus ultra evidence is the excellent post, Git Reset Demystified by Scott Chacon. It’s about git’s equivalent to svn revert — a very important function, undoing your changes. But even though Scott is very knowledgable about git and even authored the book, Pro Git, he

…never strongly understood the command beyond the handful of specific use cases that I needed it for. I knew what the command did, but not really how it was designed to work.

It’s no wonder that ordinary git users don’t fully grasp these commands. In a confirmation of my theory about git’s problems, Scott presents this 6×4 table as a learning aide:

Like studying German verb conjugations

A second example is the well written O’Reilly book Version Control with Git. It teaches the internal implementation of git before explaining how to fully use it. Or, as David Eisinger says,

…until you wrap your head around its internal model, it’s easy to wind up in a jumble of merge commits or worse.

Fixing git: two ideas

See also

The Hidden Dangers of Beautiful Themes

A Tale of Seduction and Betrayal

Some of the best-designed and officially featured WordPress themes aren’t built to handle mid-volume traffic. Just one incoming link from a semi-popular page can take your server down.

A New Blog for a Web App

The featured “News” theme that crashed my server

Everything started out smoothly. Like thousands of developers do every day, I set up a new WordPress installation to support a new web app I’m getting online. I’ve got a Linode 1536 which is perfect for this ?. It has gigs of free disk space and 800MB of unused RAM just for cache. And these virtual servers are fast. Mine hosts about 15 Rails and WordPress apps and the system load never gets up to 1.0.

For me, the hardest (and most fun) part of setting up a new blog is choosing the theme. I didn’t want to waste time, so I looked only at WordPress’s one-page “featured” themes list and chose News — a conservative theme with personality.

I wrote a few posts to get started, posted a link to one on Reddit, and went to sleep.

I Woke Up but My Server Wasn’t There

The network traffic graph gives a dramatic view of the server crash

At around 9am, I was in for a shock: no web pages were loading and it took 2 minutes to simply ssh in. There were about a million Apache processes running and the system was out of memory. Checking on Reddit, I saw that the post was getting a good amount of traffic: it was at the top of the r/programming subreddit. It had a couple of hundred up-votes; a lot, but certainly not an apocalypse. So this was odd. I also saw that someone reposted it to the Hacker News. (Nice!) Except that the posts were only noting that the site was offline (Not nice.)

Discovering the Culprit: the Theme

A helpful Hacker News reader suggested “Caching is your friend”. That was my first thought as well. WordPress by default is just a PHP app, doing a lot of repetitious work with every request. But that didn’t feel right. This was a brand new blog, after all, and the requests were all for one simple page.