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.