Compilers
In yesterday's post, I described taking a closer look at how a browser works (in particular, HTML/CSS rendering) as well as compilers, but left out discussing the missing piece connecting the two - executing JavaScript.
We can think about JavaScript execution as translating source code to machine code (which the computer understands). This step could be done through the use of an interpreter, which translates and executes line-by-line. This allows for a fast startup time, but can be slower overall since the same translation may be done over and over again. The other option is to use a compiler, which translates all the source code at once prior to execution. This allows for more optimizations but is more complex and thus slower to start.
Modern JavaScript engines like Chrome's V8 combines the 'best of both worlds'. It starts by running the source code through the interpreter, but also has a profiler that identifies parts of the code that are run repeatedly. These are then recompiled into highly-optimized machine code, allowing for impressive speed ups over time. This process is known as just-in-time (JIT) compilation.
When running microbenchmarks, I was surprised (and impressed!) to find JavaScript performance times to be comparable to Rust. What I didn't compare was memory usage, though perhaps you're already familiar with this from using Chrome. Writing high performance JavaScript is very much tied to keeping the JIT happy, which got me looking at compilers.
A discussion of how V8 makes trade-offs - running a single line of code vs iterating through a loop, memory usage in laptops vs mobile - can be found in the Google I/O talk here.
Startups
Andrey and I talked about startups over a fun coffee chat today. We have a tendency as developers to build something cool that we think will translate well into a startup, but in doing so overlook two key skills.
The first is the skill of 'making money'. This involves being mindful about the commercial aspects of the product (potential user base, how to monetize, pricing) as well as the business in general (accounting, payroll, AWS bill). Naturally the idea here is to have money in exceed money out, or at least, be able to pitch VCs that you'll end up in this state.
The second is sales. While it's easy to think of sales as a part of the first skill, it's clearer as a separate skill when you think about how you can sell something that's free. Sales more broadly involves growing the adoption of your product; a large user base helps create a large paying user base.
A useful analogy is to think about being a good developer and being good at interviews. The two skills reinforce each other but involve different training regimes. Keeping the two distinct helps us break down real-life examples into 'case studies' and assess how well they do in each dimension.
What's very interesting is how Andrey uses this framing for open source software - he leans towards building something that's cool but also something easy to explain and easy to demo.
Content: Sam Altman
I enjoyed the New Yorker profile of Sam Altman so much, I still keep the physical copy. I know, I should have kept the one on Jack Dorsey too.
The article has a brief history of YC and how it's changed under Altman, including this great excerpt.
Launching a startup in 2016 is akin to assembling an alt-rock band in 1996 or protesting the Vietnam War in 1971 - an act of youthful rebellion gone conformist. Since 2005, the year Y Combinator began, accelerators have sprung up everywhere to help transform startups from a skein of code into a bona-fide company.
Altman has since moved to leading OpenAI. He's true to form on gambling on the next moonshot, as per the advice from his post. The question for myself is, what's my success metric?
It’s useful to focus on adding another zero to whatever you define as your success metric - money, status, impact on the world, or whatever. I am willing to take as much time as needed between projects to find my next thing. But I always want it to be a project that, if successful, will make the rest of my career look like a footnote.