Worker pools in Go

A fixed set of goroutines draining a job channel.

func pool(jobs <-chan int, workers int) <-chan int {
    results := make(chan int)
    var wg sync.WaitGroup
    for i := 0; i < workers; i++ {
        wg.Add(1)
        go func() {
            defer wg.Done()
            for j := range jobs {
                results <- j * j
            }
        }()
    }
    go func() {
        wg.Wait()
        close(results)
    }()
    return results
}

How it works

1. Every worker ranges over the same jobs channel.
2. A closer goroutine waits then closes results.
3. The main goroutine collects until results close.

Keywords and builtins used here

• chan
• close
• defer
• for
• func
• go
• int
• make
• range
• return
• var

The run, in numbers

Lines

18

Characters to type

274

Tokens

92

Three-star pace

110 tpm

At the three-star pace of 110 tokens a minute, this run takes about 50 seconds.

Type this snippet

Step 1 of 5 in Patterns, step 19 of 25 in Concurrency.

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