mrb_type
非正規化(denormalized)数
sysconf(_SC_NPROCESSORS_ONLN)
mrb_http2_config_get_worker
set_config_worker
If pid equals 0, then sig is sent to every process in the process group of the calling process. killを読んだプロセスが属するグループにシグナル送信
If pid is less than -1, then sig is sent to every process in the process group whose ID is -pid. pidをグループに持つプロセスにシグナルを送る
pids=
pgrep -P 28855=> "28856\n28857\n28858\n28859\n" pids.split("\n") => ["28856", "28857", "28858", "28859"]