Description:
According to the documentations (https://dev.mysql.com/doc/refman/5.6/en/performance-schema-filtering.html#performance-sche...):
"For foreground threads (resulting from client connections), the initial INSTRUMENTED value is determined by whether the user account associated with the thread matches any row in the setup_actors table. For background threads, INSTRUMENTED is YES by default. setup_actors is not consulted because there is no associated user for background threads."
However if all rows are removed from setup_actors (thus no new foreground threads should be instrumented), new connections are still instrumented. On the other hand, the thread "thread/sql/main" (typical/always THREAD_ID = 1) changes to INSTRUMENTED = NO despite it being a background thread.
How to repeat:
1) Delete all rows in setup_actors:
DELETE FROM performance_schema.setup_actors;
2) SELECT THREAD_ID, TYPE, INSTRUMENTED FROM threads;
+-----------+------------+--------------+
| THREAD_ID | TYPE | INSTRUMENTED |
+-----------+------------+--------------+
| 1 | BACKGROUND | YES |
| 2 | BACKGROUND | YES |
| 3 | BACKGROUND | YES |
| 4 | BACKGROUND | YES |
| 5 | BACKGROUND | YES |
| 6 | BACKGROUND | YES |
| 7 | BACKGROUND | YES |
| 8 | BACKGROUND | YES |
| 9 | BACKGROUND | YES |
| 10 | BACKGROUND | YES |
| 11 | BACKGROUND | YES |
| 12 | BACKGROUND | YES |
| 13 | BACKGROUND | YES |
| 14 | BACKGROUND | YES |
| 15 | BACKGROUND | YES |
| 16 | BACKGROUND | YES |
| 18 | BACKGROUND | YES |
| 19 | BACKGROUND | YES |
| 20 | BACKGROUND | YES |
| 21 | BACKGROUND | YES |
| 22 | BACKGROUND | YES |
| 23 | BACKGROUND | YES |
| 24 | BACKGROUND | YES |
| 25 | BACKGROUND | YES |
| 26 | BACKGROUND | YES |
| 27 | BACKGROUND | YES |
| 28 | BACKGROUND | YES |
| 29 | BACKGROUND | YES |
| 30 | BACKGROUND | YES |
| 31 | BACKGROUND | YES |
| 32 | BACKGROUND | YES |
| 33 | BACKGROUND | YES |
| 34 | BACKGROUND | YES |
| 35 | BACKGROUND | YES |
| 36 | BACKGROUND | YES |
| 37 | BACKGROUND | YES |
| 38 | FOREGROUND | YES |
| 39 | FOREGROUND | YES |
+-----------+------------+--------------+
38 rows in set (0.00 sec)
3) Create new connection.
4) SELECT THREAD_ID, TYPE, INSTRUMENTED FROM threads;
+-----------+------------+--------------+
| THREAD_ID | TYPE | INSTRUMENTED |
+-----------+------------+--------------+
| 1 | BACKGROUND | NO |
| 2 | BACKGROUND | YES |
| 3 | BACKGROUND | YES |
| 4 | BACKGROUND | YES |
| 5 | BACKGROUND | YES |
| 6 | BACKGROUND | YES |
| 7 | BACKGROUND | YES |
| 8 | BACKGROUND | YES |
| 9 | BACKGROUND | YES |
| 10 | BACKGROUND | YES |
| 11 | BACKGROUND | YES |
| 12 | BACKGROUND | YES |
| 13 | BACKGROUND | YES |
| 14 | BACKGROUND | YES |
| 15 | BACKGROUND | YES |
| 16 | BACKGROUND | YES |
| 18 | BACKGROUND | YES |
| 19 | BACKGROUND | YES |
| 20 | BACKGROUND | YES |
| 21 | BACKGROUND | YES |
| 22 | BACKGROUND | YES |
| 23 | BACKGROUND | YES |
| 24 | BACKGROUND | YES |
| 25 | BACKGROUND | YES |
| 26 | BACKGROUND | YES |
| 27 | BACKGROUND | YES |
| 28 | BACKGROUND | YES |
| 29 | BACKGROUND | YES |
| 30 | BACKGROUND | YES |
| 31 | BACKGROUND | YES |
| 32 | BACKGROUND | YES |
| 33 | BACKGROUND | YES |
| 34 | BACKGROUND | YES |
| 35 | BACKGROUND | YES |
| 36 | BACKGROUND | YES |
| 37 | BACKGROUND | YES |
| 38 | FOREGROUND | YES |
| 39 | FOREGROUND | YES |
| 46 | FOREGROUND | YES |
+-----------+------------+--------------+
39 rows in set (0.00 sec)
Suggested fix:
N/A
