in glog.go [861:876]
func (l *loggingT) createFiles(sev severity) error {
now := time.Now()
// Files are created in decreasing severity order, so as soon as we find one
// has already been created, we can stop.
for s := sev; s >= infoLog && l.file[s] == nil; s-- {
sb := &syncBuffer{
logger: l,
sev: s,
}
if err := sb.rotateFile(now); err != nil {
return err
}
l.file[s] = sb
}
return nil
}