Two ways from StackOverflow
Builtin Way Using “syscall”
func GetCPU() int64 {
usage := new(syscall.Rusage)
syscall.Getrusage(syscall.RUSAGE_SELF, usage)
return usage.Utime.Nano() + usage.Stime.Nano()
}
Explanation
Utime: user CPU time
Stime: system CPU time
RUSAGE_SELF: means it’s measuring the “calling” process
man 2 getrusage for more information
NOTE:
The documentation for syscall.Timeval suggests that Nano() returns the time in nanoseconds since the Unix epoch, but in my tests and looking at the implementation it appears actually to return just the CPU time in nanoseconds, not in nanoseconds since the Unix epoch.
Using CGO
Do it in a platform-specific way.
man 3 clock_gettime
Similarly you can use CLOCK_PROCESS_CPUTIME_ID to measure process CPU time and CLOCK_MONOTONIC for elapsed time.
package main
/*
#include <pthread.h>
#include <time.h>
#include <stdio.h>
static long long getThreadCpuTimeNs() {
struct timespec t;
if (clock_gettime(CLOCK_THREAD_CPUTIME_ID, &t)) {
perror("clock_gettime");
return 0;
}
return t.tv_sec * 1000000000LL + t.tv_nsec;
}
*/
import "C"
import "fmt"
import "time"
func main() {
cputime1 := C.getThreadCpuTimeNs()
doWork()
cputime2 := C.getThreadCpuTimeNs()
fmt.Printf("CPU time = %d ns\n", (cputime2 - cputime1))
}
func doWork() {
x := 1
for i := 0; i < 100000000; i++ {
x *= 11111
}
time.Sleep(time.Second)
}
Further Reading
Using third-party-extended-pprof tools: fgprof
The Builtin Go toolchain profilers that are often used to profile CPU measures “on-CPU” only, so there is an “extend” version fgprof on Github
package main
import(
_ "net/http/pprof"
"github.com/felixge/fgprof"
)
func main() {
http.DefaultServeMux.Handle("/debug/fgprof", fgprof.Handler())
go func() {
log.Println(http.ListenAndServe(":6060", nil))
}()
// <code to profile>
}
go tool pprof --http=:6061 http://localhost:6060/debug/fgprof?seconds=3
References
- https://stackoverflow.com/questions/55990074/how-to-measure-execution-time-of-function-in-golang-excluding-waiting-time
- https://github.com/felixge/fgprof
