Pleas help I am not able to find why number of sessions increasing?

test@(none) 01:54:44>select * from information_schema.processlist where command!=’sleep’ and user!=’system user’\G
*************************** 1. row ***************************
ID: 101176
USER: test
HOST: localhost
DB: test
COMMAND: Query
TIME: 64
STATE: Waiting for table metadata lock
INFO: alter table t1 add column name5 char(10)
TIME_MS: 64148
ROWS_SENT: 0
ROWS_EXAMINED: 0

test@(none) 01:55:30>CALL test.procShowMetadataLockSummary();
Query OK, 0 rows affected (0.00 sec)

test@(none) 01:55:53>SELECT OBJECT_TYPE, OBJECT_SCHEMA, OBJECT_NAME, LOCK_TYPE, LOCK_STATUS, THREAD_ID, PROCESSLIST_ID, PROCESSLIST_INFO FROM performance_schema.metadata_locks INNER JOIN performance_schema.threads ON THREAD_ID = OWNER_THREAD_ID WHERE PROCESSLIST_ID CONNECTION_ID();
+————-+——————–+——————-+————-+————-+———–+—————-+——————+
| OBJECT_TYPE | OBJECT_SCHEMA | OBJECT_NAME | LOCK_TYPE | LOCK_STATUS | THREAD_ID | PROCESSLIST_ID | PROCESSLIST_INFO |
+————-+——————–+——————-+————-+————-+———–+—————-+——————+
| TABLE | performance_schema | global_status | SHARED_READ | GRANTED | 53741 | 53559 | NULL |
| TABLE | performance_schema | session_variables | SHARED_READ | GRANTED | 53741 | 53559 | NULL |
+————-+——————–+——————-+————-+————-+———–+—————-+——————+
2 rows in set (0.05 sec)

But when i restart mysqld, I can see it.
He is unstable

However, I can not view the thread holding the MDL lock.
I refer to the following article
https://www.percona.com/blog/2016/12/28/quickly-troubleshooting-metadata-locks-mysql-5-7/

the test is described below

The following is the official version of the phenomenon (5.7.19)
test@test 06:13:51>select * from performance_schema.metadata_locks\G
*************************** 1. row ***************************
OBJECT_TYPE: TABLE
OBJECT_SCHEMA: performance_schema
OBJECT_NAME: metadata_locks
OBJECT_INSTANCE_BEGIN: 140091634556304
LOCK_TYPE: SHARED_READ
LOCK_DURATION: TRANSACTION
LOCK_STATUS: GRANTED
SOURCE: sql_parse.cc:5993
OWNER_THREAD_ID: 30
OWNER_EVENT_ID: 52
1 row in set (0.00 sec)

test@test 06:13:55>select * from performance_schema.setup_instruments where name like ‘wait/lock/metadata/sql/mdl’;
+—————————-+———+——-+
| NAME | ENABLED | TIMED |
+—————————-+———+——-+
| wait/lock/metadata/sql/mdl | YES | NO |
+—————————-+———+——-+
1 row in set (0.00 sec)

The following is the percona version of the phenomenon (5.7.19)
dbadmin@test 10:03:01>select * from performance_schema.metadata_locks\G
Empty set (0.00 sec)

dbadmin@test 10:12:19>select * from performance_schema.setup_instruments where name like ‘wait/lock/metadata/sql/mdl’;
+—————————-+———+——-+
| NAME | ENABLED | TIMED |
+—————————-+———+——-+
| wait/lock/metadata/sql/mdl | YES | NO |
+—————————-+———+——-+
1 row in set (0.00 sec)

thank you very mach.