$ cat post/ps-aux-at-midnight-/-we-kept-it-running-on-hope-/-a-ghost-in-the-pipe.md
ps aux at midnight / we kept it running on hope / a ghost in the pipe
Title: WebAssembly Woes: When Rust Isn’t Enough
August 8, 2022 was another quiet day in my life as an engineering manager. I woke up to the usual morning routine and made my way into the office. The tech world had its share of buzz this month—AI and LLMs were still a hot topic after ChatGPT’s debut, and platform engineering was becoming mainstream. But for me, it was all about making our platform more efficient.
I started with a quick review of our codebase—a mix of Rust, Node.js, Python, and Go. Our backend infrastructure was humming along nicely, but there was always room for improvement. Today, I had my sights set on optimizing one of our microservices that processed complex computations. The current implementation in Rust was fast, but it wasn’t without its quirks.
The service was designed to handle a wide range of tasks, from simple arithmetic operations to more complex matrix manipulations. It ran perfectly fine most of the time, but occasionally we’d see a spike in memory usage or a few crashes. My initial thoughts were that Rust’s performance and safety guarantees made it an excellent choice for this task. But something just wasn’t right.
I spent hours stepping through the code, looking for potential bottlenecks. After much head-scratching, I realized there was a subtle race condition in our concurrency handling. The issue only manifested under high load, which explained why we were seeing these intermittent problems but not every time.
Fixing the race condition was straightforward enough—adding a few mutexes and ensuring thread safety. But then I had an epiphany: maybe it wasn’t Rust’s fault at all. Could WebAssembly be a better fit for this task? We hadn’t explored that option yet, as we were already comfortable with Rust’s speed and stability.
I decided to test the waters by rewriting our computation-heavy logic in C++ and compiling it down to WebAssembly. The idea was simple: serve static binaries at runtime via WASM, which would allow us to leverage a more mature C++ ecosystem for complex tasks without compromising on performance or safety.
After some trial and error, I managed to get the C++ code running smoothly within our Rust-based backend using wasm-bindgen. It was a bit of a hacky solution, but it worked. The initial benchmarks showed a significant improvement in both speed and memory usage compared to our previous implementation. However, integrating WebAssembly into our existing infrastructure proved more challenging than anticipated.
The next day, I faced the challenge of merging this new piece of code with our microservices. It wasn’t just about writing good C++; I had to ensure that we could safely unload and reload WASM modules without disrupting user sessions. This meant figuring out how to manage state between executions and handling potential race conditions in a multi-threaded environment.
As I worked through these issues, I found myself reflecting on the broader trends in tech at the time. AI and LLMs were dominating headlines, but for me, it was all about making our platform more efficient and reliable. The Physical Buttons article made me think about how we interact with technology and whether we’re sometimes too quick to dismiss traditional methods for something shinier.
The Google Cloud incident highlighted the ongoing challenges of cloud infrastructure—something that hits close to home given my experience with managing distributed systems. It’s moments like these that remind us that no matter how sophisticated our tools become, basic reliability still matters.
In the end, we landed on a hybrid approach: keeping Rust for simpler tasks and leveraging WebAssembly for those heavy lifting jobs where performance really mattered. It wasn’t a perfect solution, but it was one step closer to making our platform faster and more efficient.
As I wrapped up my day, I couldn’t help but feel grateful for the small victories in tech that come from solving real problems. Sometimes, the most interesting challenges aren’t about cutting-edge technologies, but about finding the right balance between what we have today and what we need tomorrow.
That’s it for August 8, 2022—another day spent wrestling with code, tools, and real-world engineering problems. Stay tuned for more updates!