I have so many docker container , and appear this problem, why there are so many session-xxxx.scope.d files and directorys in /run/systemd/system/ , I find my container ssh delays too slowly about 30s , I am puzzled that why so many session-xxxx.scope.d directorys didn't be deleted? I don't know if this is relate to https://github.com/systemd/systemd/issues/2925 ```#rpm -q dbusdbus-1.6.12-13.1.el7.x86_64``````#rpm -q systemdsystemd-219-19.el7_2.13.x86_64.rpm ```so many session files ```[root@docker011160000047.xxxx /home/ahao.mah]#ls -ld /run/systemd/system/session-*.scope* |wc -l25981``````[root@docker011160000047.xxxx /home/ahao.mah]#ls -ld /run/systemd/system/session-*.scope* |head -n 100-rw-r--r-- 1 root root  17 Mar  7 17:53 /run/systemd/system/session-1000019.scopedrwxr-xr-x 2 root root 140 Mar  7 17:53 /run/systemd/system/session-1000019.scope.d-rw-r--r-- 1 root root  17 Mar  7 17:53 /run/systemd/system/session-1000020.scopedrwxr-xr-x 2 root root 140 Mar  7 17:53 /run/systemd/system/session-1000020.scope.d-rw-r--r-- 1 root root  17 Mar  7 17:56 /run/systemd/system/session-1000404.scopedrwxr-xr-x 2 root root 140 Mar  7 17:56 /run/systemd/system/session-1000404.scope.d-rw-r--r-- 1 root root  17 Mar  1 19:17 /run/systemd/system/session-100056.scopedrwxr-xr-x 2 root root 140 Mar  1 19:17 /run/systemd/system/session-100056.scope.d-rw-r--r-- 1 root root  17 Mar  7 18:00 /run/systemd/system/session-1000871.scopedrwxr-xr-x 2 root root 140 Mar  7 18:00 /run/systemd/system/session-1000871.scope.d-rw-r--r-- 1 root root  17 Mar  7 18:01 /run/systemd/system/session-1001130.scopedrwxr-xr-x 2 root root 140 Mar  7 18:01 /run/systemd/system/session-1001130.scope.d-rw-r--r-- 1 root root  17 Mar  1 19:20 /run/systemd/system/session-100129.scopedrwxr-xr-x 2 root root 140 Mar  1 19:20 /run/systemd/system/session-100129.scope.d-rw-r--r-- 1 root root  17 Mar  7 18:04 /run/systemd/system/session-1001450.scopedrwxr-xr-x 2 root root 140 Mar  7 18:04 /run/systemd/system/session-1001450.scope.d-rw-r--r-- 1 root root  17 Mar  7 18:05 /run/systemd/system/session-1001572.scopedrwxr-xr-x 2 root root 140 Mar  7 18:05 /run/systemd/system/session-1001572.scope.d-rw-r--r-- 1 root root  17 Mar  7 18:05 /run/systemd/system/session-1001573.scopedrwxr-xr-x 2 root root 140 Mar  7 18:05 /run/systemd/system/session-1001573.scope.d-rw-r--r-- 1 root root  17 Mar  7 18:08 /run/systemd/system/session-1001866.scopedrwxr-xr-x 2 root root 140 Mar  7 18:08 /run/systemd/system/session-1001866.scope.d-rw-r--r-- 1 root root  17 Mar  7 18:08 /run/systemd/system/session-1001867.scopedrwxr-xr-x 2 root root 140 Mar  7 18:08 /run/systemd/system/session-1001867.scope.d-rw-r--r-- 1 root root  17 Mar  7 18:10 /run/systemd/system/session-1002216.scopedrwxr-xr-x 2 root root 140 Mar  7 18:10 /run/systemd/system/session-1002216.scope.d-rw-r--r-- 1 root root  17 Mar  7 18:10 /run/systemd/system/session-1002217.scopedrwxr-xr-x 2 root root 140 Mar  7 18:10 /run/systemd/system/session-1002217.scope.d-rw-r--r-- 1 root root  17 Mar  7 18:16 /run/systemd/system/session-1002918.scopedrwxr-xr-x 2 root root 140 Mar  7 18:16 /run/systemd/system/session-1002918.scope.d-rw-r--r-- 1 root root  17 Mar  7 18:20 /run/systemd/system/session-1003641.scopedrwxr-xr-x 2 root root 140 Mar  7 18:20 /run/systemd/system/session-1003641.scope.d-rw-r--r-- 1 root root  17 Mar  7 18:25 /run/systemd/system/session-1004120.scopedrwxr-xr-x 2 root root 140 Mar  7 18:25 /run/systemd/system/session-1004120.scope.d-rw-r--r-- 1 root root  17 Mar  1 19:25 /run/systemd/system/session-100418.scope``````[root@docker011160000047.xxxx /home/ahao.mah]#cat /run/systemd/system/session-*.scope.d/50-Description.conf[Unit]Description=Session 1000019 of user mysql[Unit]Description=Session 1000020 of user root[Unit]Description=Session 1000404 of user mysql[Unit]Description=Session 100056 of user root[Unit]Description=Session 1000871 of user mysql[Unit]Description=Session 1001130 of user mysql[Unit]Description=Session 100129 of user mysql[Unit]Description=Session 1001450 of user root[Unit]Description=Session 1001572 of user mysql[Unit]Description=Session 1001573 of user root[Unit]Description=Session 1001866 of user root[Unit]Description=Session 1001867 of user mysql[Unit]Description=Session 1002216 of user mysql[Unit]Description=Session 1002217 of user mysql[Unit]Description=Session 1002918 of user mysql```looks like there is not so many connections ```[root@docker011160000047.xxxx /home/ahao.mah]#netstat -antlupe | wc -l35[root@docker011160000047.xxxx /home/ahao.mah]#lsof -i :22 |wc -l6```
why so many sessions scope file didn't been deleted?
systemd