BoundingResourceUse

Bounding resource use

To bound a program's use of a limited resource, like memory, have goroutines synchronize their use of that resource using a buffered channel (i.e., use the channel as a semaphore):

const (
  AvailableMemory = 10 << 20  // 10 MB
  AverageMemoryPerRequest = 10 << 10  // 10 KB
  MaxOutstanding = AvailableMemory / AverageMemoryPerRequest
)
var sem = make(chan int, MaxOutstanding)

func Serve(queue chan *Request) {
    for {
        sem <- 1        // Block until there's capacity to process a request.
        req := <-queue
        go handle(req)  // Don't wait for handle to finish.
    }
}

func handle(r *Request) {
    process(r)  // May take a long time & use a lot of memory or CPU
    <-sem       // Done; enable next request to run.
}

References

Effective Go's discussion of channels: http://golang.org/doc/effective_go.html#channels