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> they had some overly chatty calls between AWS lambda functions and S3. They were able to re-use most of their working code by combining it into a single long

by amluto 4y ago

> they had some overly chatty calls between AWS lambda functions and S3. They were able to re-use most of their working code by combining it into a single long running microservice that is horizontally scaled using ECS, and which is invoked via a lambda function. This is only one of many microservices that make up the Prime Video application. The problem is that they called this refactoring a microservice to monolith transition, when it’s clearly a microservice refactoring step If I understood the post at all, I disagree. One can spend hundreds of HN comments discussing technology stacks, monoliths, etc, and this is important: it affects maintainability, developer hours, and money spent on orchestration. For some applications, almost the entire workload is orchestration, and this discussion makes sense. But for this workload, actual work is being done, and it can be quantified and priced. So let’s get to the basics: an uncompressed 1080p video stream is something like 3 Gbps. It costs a certain amount of CPU to decompress. It costs a certain amount of CPU to analyze. These have price tags. You can pay for that CPU at EC2 rates or on-prem rates or Lambda rates or whatever. You can calculate this! And you pay for that bandwidth. You can pay for 3Gbps per stream using S3: you pay S3 and you pay EC2 (or whatever) because that uses 1/10th of the practical maximum EC2 <-> S3 bandwidth per instance. Or you pay for the fraction of main memory bandwidth used if you decode and analyze on the same EC2 instance (or Lambda function or whatever). Or you pay for the fraction of cache bandwidth used if you decide partial frames and analyze without ever sending to memory. And you’ll find that S3 is not “chatty”. It’s catastrophic. In fact, any use of microservices here is likely catastrophic if not carefully bound to the same machine.

jayd16 4y ago
So it didn't make sense to separate some functionality. So what? No one who advocates microservices would say you can cut a service along any arbitrary line and expect good results.
jiggawatts 4y ago
This is called mechanical sympathy and most architects and developers do not have it. Computer architectures encompass 13 orders of magnitude of performance! That's roughly the difference between something like a trivial function call processing data in L1 cache to a remote call out to something in another region. People often make relatively "small" mistakes of 3 or 4 orders of magnitude, which is still crazy if you think about it, but that's considered to be a minor sin relative to making the architecture diagram look pretty.

by amluto 4y ago

jayd16 4y ago

So it didn't make sense to separate some functionality. So what? No one who advocates microservices would say you can cut a service along any arbitrary line and expect good results.

jiggawatts 4y ago

This is called mechanical sympathy and most architects and developers do not have it. Computer architectures encompass 13 orders of magnitude of performance! That's roughly the difference between something like a trivial function call processing data in L1 cache to a remote call out to something in another region. People often make relatively "small" mistakes of 3 or 4 orders of magnitude, which is still crazy if you think about it, but that's considered to be a minor sin relative to making the architecture diagram look pretty.