// previously destroyed p, and transitions it to status _Pgcstop.
func (pp *p) init(id int32) {
	pp.id = id
	pp.status = _Pgcstop
	pp.sudogcache = pp.sudogbuf[:0]
	pp.deferpool = pp.deferpoolbuf[:0]
	pp.wbBuf.reset()
	if pp.mcache == nil {
		if id == 0 {
			if mcache0 == nil {
				throw("missing mcache?")
			}
			// Use the bootstrap mcache0. Only one P will get