为什么php fpm status max active PROCESS可以大于pm.max_子进程？

我在phpfpm.conf中设置pm.max_children=100和pm=dynamic，并在nginx.conf中启用phpfpm status api。但是我在status api的结果中发现了“max active processs=108”。为什么活动进程可以大于pm.max_子进程

pool:                 www
process manager:      dynamic
start time:           14/Feb/2019:11:22:50 +0800
start since:          7077
accepted conn:        513727
listen queue:         0
max listen queue:     21
listen queue len:     128
idle processes:       1
active processes:     19
total processes:      20
max active processes: 108
max children reached: 0
slow requests:        0

这是我在phpfpm.conf中的配置：

pm = dynamic
pm.max_children = 100
pm.start_servers = 12
pm.min_spare_servers = 5
pm.max_spare_servers = 20
pm.max_requests = 100