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53 lines
1.2 KiB
Go
53 lines
1.2 KiB
Go
// The primary mechanism for managing state in Go is
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// communication over channels. We saw this for example
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// with [worker pools](worker-pools). There are a few other
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// options for managing state though. Here we'll
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// look at using the `sync/atomic` package for _atomic
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// counters_ accessed by multiple goroutines.
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package main
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import (
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"fmt"
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"sync"
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"sync/atomic"
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)
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func main() {
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// We'll use an unsigned integer to represent our
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// (always-positive) counter.
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var ops uint64
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// A WaitGroup will help us wait for all goroutines
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// to finish their work.
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var wg sync.WaitGroup
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// We'll start 50 goroutines that each increment the
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// counter exactly 1000 times.
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for i := 0; i < 50; i++ {
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wg.Add(1)
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go func() {
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for c := 0; c < 1000; c++ {
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// To atomically increment the counter we
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// use `AddUint64`, giving it the memory
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// address of our `ops` counter with the
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// `&` syntax.
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atomic.AddUint64(&ops, 1)
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}
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wg.Done()
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}()
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}
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// Wait until all the goroutines are done.
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wg.Wait()
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// It's safe to access `ops` now because we know
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// no other goroutine is writing to it. Reading
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// atomics safely while they are being updated is
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// also possible, using functions like
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// `atomic.LoadUint64`.
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fmt.Println("ops:", ops)
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}
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