// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime
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import (
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"runtime/internal/atomic"
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"unsafe"
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)
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// GOMAXPROCS sets the maximum number of CPUs that can be executing
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// simultaneously and returns the previous setting. If n < 1, it does not
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// change the current setting.
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// The number of logical CPUs on the local machine can be queried with NumCPU.
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// This call will go away when the scheduler improves.
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func GOMAXPROCS(n int) int {
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if GOARCH == "wasm" && n > 1 {
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n = 1 // WebAssembly has no threads yet, so only one CPU is possible.
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}
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lock(&sched.lock)
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ret := int(gomaxprocs)
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unlock(&sched.lock)
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if n <= 0 || n == ret {
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return ret
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}
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stopTheWorld("GOMAXPROCS")
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// newprocs will be processed by startTheWorld
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newprocs = int32(n)
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startTheWorld()
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return ret
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}
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// NumCPU returns the number of logical CPUs usable by the current process.
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//
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// The set of available CPUs is checked by querying the operating system
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// at process startup. Changes to operating system CPU allocation after
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// process startup are not reflected.
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func NumCPU() int {
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return int(ncpu)
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}
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// NumCgoCall returns the number of cgo calls made by the current process.
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func NumCgoCall() int64 {
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var n int64
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for mp := (*m)(atomic.Loadp(unsafe.Pointer(&allm))); mp != nil; mp = mp.alllink {
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n += int64(mp.ncgocall)
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}
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return n
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}
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// NumGoroutine returns the number of goroutines that currently exist.
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func NumGoroutine() int {
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return int(gcount())
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}
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