Simplest possible solution for communication between services is to use JSON over HTTP. Though JSON has many obvious advantages - it’s human readable, well understood, and typically performs well - it also has its issues. In the case of internal services the structured formats, such as Google’s Protocol Buffers, are a better choice than JSON for encoding data.

gRPC uses protobuf by default, and it's faster because it's binary and it's type-safe. I coded a demonstration project to benchmark classic REST API using JSON over HTTP vs same API in gRPC using Go.

This repository contains 2 equal APIs: gRPC using Protobuf and JSON over HTTP. The goal is to run benchmarks for 2 approaches and compare them. APIs have 1 endpoint to create user, containing validation of request. Request, validation and response are the same in 2 packages, so we're benchmarking only mechanism itself. Benchmarks also include response parsing.

I use Go 1.9 and results show that gRPC is 10 times faster for my API:

BenchmarkGRPCProtobuf-8        10000        197919 ns/op
BenchmarkJSONHTTP-8             1000       1720124 ns/op

CPU usage comparison

Restart applications, then use profiling tool pprof during 30 sec when the client is talking to the server with these commands:

go tool pprof http://localhost:6060/debug/pprof/profile
go tool pprof http://localhost:6061/debug/pprof/profile

Run tests to get client connections. Then in each pprof run top to see CPU usage.
My results show that Protobuf consumes less ressources, 30% less.

Test it by your own

If you want to test it by yourself you can clone this repository and run the following commands:

glide i
go run grpc/main.go
go run json/main.go
go test -bench=.

Conclusion

It's totally clear that for internal-only communication it's better to use gRPC, your client calls will be much cleaner, you don't have to mess with types and serialization, because gRPC does it for you.

Original post in my Blog