Drop database will not delete abandoned TokuDB files after getting error from storage engine

[Shahriyar Rzayev]

Wrote a simple script for creating "Too many open files" error in Percona Server with TokuDB tables.
After a while got:

23 (HY000): Out of resources when opening file './tokudb_tables/' (Errcode: 24 - Too many open files)
1030 (HY000): Got error 1 from storage engine
1030 (HY000): Got error 24 from storage engine
1030 (HY000): Got error 24 from storage engine
23 (HY000): Out of resources when opening file './tokudb_tables/' (Errcode: 24 - Too many open files)
1030 (HY000): Got error 1 from storage engine
1030 (HY000): Got error 24 from storage engine
1030 (HY000): Got error 24 from storage engine
1030 (HY000): Got error 24 from storage engine
23 (HY000): Out of resources when opening file './tokudb_tables/' (Errcode: 24 - Too many open files)

Then restarted MySQL and tried to drop tokudb_tables database:

mysql> drop database tokudb_tables;
Query OK, 11878 rows affected (1 min 11.90 sec)

But there are abandoned TokuDB files in tokudb_data_dir after drop database:

Key files:

root@percona-XPS-15:/home/tokudb_data_dir# ls -l | grep _tokudb_tables_t | grep -i firstname | wc -l
11733

Prrimary key files:

root@percona-XPS-15:/home/tokudb_data_dir# ls -l | grep _tokudb_tables_t | grep -i main | wc -l
95

Stat files:

root@percona-XPS-15:/home/tokudb_data_dir# ls -l | grep _tokudb_tables_t | grep stat | wc -l
155

Some of files:
-rw-rw---- 1 mysql mysql 0 нояб. 13 12:51 _tokudb_tables_t29390_key_firstname_2c97d_3_1c.tokudb
-rw-rw---- 1 mysql mysql 0 нояб. 13 12:51 _tokudb_tables_t29391_key_firstname_2c97f_3_1c.tokudb
-rw-rw---- 1 mysql mysql 0 нояб. 13 12:51 _tokudb_tables_t29392_key_firstname_2c981_3_1c.tokudb
-rw-rw---- 1 mysql mysql 0 нояб. 13 12:51 _tokudb_tables_t29393_key_firstname_2c983_3_1c.tokudb

After all we must manually delete these files.

[George Ormond Lorch III (gl-az)]

https://tokutek.atlassian.net/browse/DB-960

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PS-1670