The log package has some benchmarks, maybe make the change and see if it
makes a difference.
On Wednesday, 7 September 2016 02:46:09 UTC+10, mwor...@gmail.com wrote:
>
> Hey, It's commented "release lock while getting caller info - it's
> expensive" in source code of /src/log/log.go line:150.
>
> I'm confused with what makes it expensive if we didn't unlock the l.mu ?
> Does goroutines have context ?
>
> func (l *Logger) Output(calldepth int, s string) error {
> now := time.Now() // get this early.
> var file string
> var line int
> l.mu.Lock()
> defer l.mu.Unlock()
> if l.flag&(Lshortfile|Llongfile) != 0 {
> // release lock while getting caller info - it's expensive.
> l.mu.Unlock()
> var ok bool
> _, file, line, ok = runtime.Caller(calldepth)
> if !ok {
> file = "???"
> line = 0
> }
> l.mu.Lock()
> }
> l.buf = l.buf[:0]
> l.formatHeader(&l.buf, now, file, line)
> l.buf = append(l.buf, s...)
> if len(s) == 0 || s[len(s)-1] != '\n' {
> l.buf = append(l.buf, '\n')
> }
> _, err := l.out.Write(l.buf)
> return err
> }
>
> AND
>
> What will happen if I moved the _, file, line, ok =
> runtime.Caller(calldepth) like below? Is better than the upper one ?
>
> func (l *Logger) Output(calldepth int, s string) error {
> now := time.Now() // get this early.
> var file string
> var line int
>
> //moved here
> var ok bool
> _, file, line, ok = runtime.Caller(calldepth)
>
> l.mu.Lock()
> defer l.mu.Unlock()
>
> l.buf = l.buf[:0]
> if l.flag&(Lshortfile|Llongfile) != 0 {
> if !ok {
> file = "???"
> line = 0
> }
> l.formatHeader(&l.buf, now, file, line)
> }
>
> l.buf = append(l.buf, s...)
> if len(s) == 0 || s[len(s)-1] != '\n' {
> l.buf = append(l.buf, '\n')
> }
> _, err := l.out.Write(l.buf)
> return err
> }
>
> Thanks for all
>
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