1 // Copyright 2009 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package runtime 6 7 import ( 8 "runtime/internal/atomic" 9 "unsafe" 10 ) 11 12 // GOMAXPROCS sets the maximum number of CPUs that can be executing 13 // simultaneously and returns the previous setting. If n < 1, it does not 14 // change the current setting. 15 // The number of logical CPUs on the local machine can be queried with NumCPU. 16 // This call will go away when the scheduler improves. 17 func GOMAXPROCS(n int) int { 18 if GOARCH == "wasm" && n > 1 { 19 n = 1 // WebAssembly has no threads yet, so only one CPU is possible. 20 } 21 22 lock(&sched.lock) 23 ret := int(gomaxprocs) 24 unlock(&sched.lock) 25 if n <= 0 || n == ret { 26 return ret 27 } 28 29 stopTheWorld("GOMAXPROCS") 30 31 // newprocs will be processed by startTheWorld 32 newprocs = int32(n) 33 34 startTheWorld() 35 return ret 36 } 37 38 // NumCPU returns the number of logical CPUs usable by the current process. 39 // 40 // The set of available CPUs is checked by querying the operating system 41 // at process startup. Changes to operating system CPU allocation after 42 // process startup are not reflected. 43 func NumCPU() int { 44 return int(ncpu) 45 } 46 47 // NumCgoCall returns the number of cgo calls made by the current process. 48 func NumCgoCall() int64 { 49 var n int64 50 for mp := (*m)(atomic.Loadp(unsafe.Pointer(&allm))); mp != nil; mp = mp.alllink { 51 n += int64(mp.ncgocall) 52 } 53 return n 54 } 55 56 // NumGoroutine returns the number of goroutines that currently exist. 57 func NumGoroutine() int { 58 return int(gcount()) 59 } 60 61 //go:linkname debug_modinfo runtime/debug.modinfo 62 func debug_modinfo() string { 63 return modinfo 64 } 65