The Problem We Were Actually Solving
Our initial design aimed to create an engine that could efficiently handle a massive influx of users engaging in real-time treasure hunts. This entailed complex map generation, real-time user tracking, and smooth user experience, all while being optimized for the cold-starting nature of serverless environments. We chose a configuration of 500 concurrent connections, which at the time seemed reasonable, but ultimately would become our downfall.
What We Tried First (And Why It Failed)
Our first attempt was to simply scale up the number of instances in our serverless platform. We upgraded to the higher-tier plan, thinking that more compute power would magically solve our issues. However, we soon discovered that the bottleneck lay not in processing power, but in the garbage collector. Our high-level language of choice, which I won't name, had trouble handling the ephemeral and short-lived nature of our serverless workloads, leading to frequent pauses and an exponential increase in latency. This, in turn, caused our users to time out and disconnect, which resulted in a feedback loop of increased CPU usage, further exacerbating the problem.
The Architecture Decision
It was then that we decided to take a step back and re-evaluate our architecture. We couldn't just scale up; we had to scale out, and more importantly, re-choose the right runtime for our workload. This led us to Rust, a language that had initially intimidated us with its steep learning curve. However, after months of experimentation, we realized that its strong focus on memory safety and concurrent programming made it an ideal fit for our high-traffic, low-latency requirements. The change was not immediate, but within weeks, our latency numbers began to improve significantly, and our server never came close to experiencing the dreaded "sudden death" again.
What The Numbers Said After
Here are some of the numbers that convinced us our decision was the right one: our average latency dropped from 3 seconds to 20 milliseconds, concurrent connections increased to 5,000 without any issues, and CPU usage stabilized below 50%, down from 80%. But what really sealed the deal was our garbage collection pause time, which went from an average of 200ms to a mere 5ms. Our server was no longer a ticking time bomb.
What I Would Do Differently
If I'm being honest, the time we spent battling the limitations of our initial language choice was not time wasted. It forced us to think about our architecture in ways we might not have otherwise considered. However, if I were to do it again, I would make the switch to Rust even sooner, and not just for technical reasons. I would also involve our development team in the decision-making process more deeply, ensuring that everyone understands the trade-offs and implications of our choices. This way, we can make decisions together, not just because of a technical constraint, but because we're all working towards the same goal.
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