We will implement backpressure as a middleware. The backpressure can be applied at selected paths after determining which endpoints are more prone to high load.

Consequences

The system should be able to shed some load and handle request without failing.

However, requests will be dropped for some clients until the system is able to serve them.

Running the example will show the following:

➜  go-advance-concurrency git:(master) ✗ go run backpressure/main.go
send: 50
drop: 11
drop: 14
drop: 17
drop: 20
drop: 22
drop: 24
drop: 27
drop: 28
drop: 33
drop: 37
drop: 39
drop: 42
drop: 45
recv: 37 worker: 0
program exiting

Here, we send 50 requests. However, only 37 is received. The remainder has been dropped because the system cannot handle the request capacity.