Buffer channel size limit

php editor Strawberry introduces the buffer channel size limit to you. In computer systems, the size of a buffer channel refers to the maximum capacity that data can be stored during transmission. This size limit has an important impact on the speed and efficiency of data transfer. If the buffer channel size is too small, data transmission may be delayed and blocked; if the buffer channel size is too large, too many system resources will be occupied. Therefore, setting the buffer channel size appropriately is the key to ensuring smooth data transmission. In actual applications, we can adjust the buffer channel size according to needs and system configuration to achieve the best performance and effect.

Question content

Hi, I wrote this code to simulate sending an email asynchronously, but if I send 500 concurrent requests to this server, the first 100 requests will be able to send it The email is queued into the channel without blocking, but subsequent requests will block until there is space available in the channel. This may cause a bottleneck on my system

package main

import (
    "fmt"
    "net/http"
    "time"
)
var count = 0;

var queue chan int

func sendEmail(){
    for email := range queue {
        time.Sleep(2 * time.Second)
        fmt.Println(email)
    }
}

func main() {
    go sendEmail()

    queue = make(chan int, 100)
    defer close(queue)

    http.ListenAndServe(":5000", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        count++
        queue <- count
        w.Write([]byte("email will be sent shortly"))
    }))
}

So what should be the maximum buffer size I can set for a channel? But again, if the number of concurrent requests is significantly larger than the buffer size, blocking may still occur. What is the best way to handle this situation

Workaround

To be clear, this is not specific to Go, this will happen wherever there are queues. At some point you will run out of resources, either memory or disk (if the queue is durable).

You need to decide what to do and how to provide feedback to the sender, this is called backpressure. This is a big topic, for example:

• https://ferd.ca/queues-don-t-fix-overload.html. This assumes Erlang as the language, the difference compared to Go is that queues are not bound by default, but the explanations in this article will be useful for "getting it" no matter which language you use.
• https://blog.nelhage.com/post/systems-at-capacity/. This doesn't assume a specific programming language and is another very useful explanation of everything covered.

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