diff options
| author | unknown <ingo@mysql.com> | 2006-05-29 15:26:23 +0200 |
|---|---|---|
| committer | unknown <ingo@mysql.com> | 2006-05-29 15:26:23 +0200 |
| commit | 4f8407b6315736ab52b49e1e248e7585614c3f20 (patch) | |
| tree | 59a370c72ba71b6114afc928164b485e2d1dd78c /mysql-test/t/lock_multi.test | |
| parent | 0086d5abd9d59dc984d402e07a6df6f9c447f098 (diff) | |
| download | mariadb-git-4f8407b6315736ab52b49e1e248e7585614c3f20.tar.gz | |
Bug#19815 - CREATE/RENAME/DROP DATABASE can deadlock on a global read lock
The order of acquiring LOCK_mysql_create_db
and wait_if_global_read_lock() was wrong. It could happen
that a thread held LOCK_mysql_create_db while waiting for
the global read lock to be released. The thread with the
global read lock could try to administrate a database too.
It would first try to lock LOCK_mysql_create_db and hang...
The check if the current thread has the global read lock
is done in wait_if_global_read_lock(), which could not be
reached because of the hang in LOCK_mysql_create_db.
Now I exchanged the order of acquiring LOCK_mysql_create_db
and wait_if_global_read_lock(). This makes
wait_if_global_read_lock() fail with an error message for
the thread with the global read lock. No deadlock happens.
mysql-test/r/lock_multi.result:
Bug#19815 - CREATE/RENAME/DROP DATABASE can deadlock on a global read lock
The test result
mysql-test/t/lock_multi.test:
Bug#19815 - CREATE/RENAME/DROP DATABASE can deadlock on a global read lock
The test case
sql/sql_db.cc:
Bug#19815 - CREATE/RENAME/DROP DATABASE can deadlock on a global read lock
Exchanged the order of acquiring LOCK_mysql_create_db
and wait_if_global_read_lock().
Diffstat (limited to 'mysql-test/t/lock_multi.test')
| -rw-r--r-- | mysql-test/t/lock_multi.test | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/mysql-test/t/lock_multi.test b/mysql-test/t/lock_multi.test index 0d2266fc2ae..c7d2bcdfbc5 100644 --- a/mysql-test/t/lock_multi.test +++ b/mysql-test/t/lock_multi.test @@ -107,3 +107,38 @@ show columns from t1; connection locker; unlock tables; drop table t1; + +# +# Bug#19815 - CREATE/RENAME/DROP DATABASE can deadlock on a global read lock +# +connect (con1,localhost,root,,); +connect (con2,localhost,root,,); +# +connection con1; +CREATE DATABASE mysqltest_1; +FLUSH TABLES WITH READ LOCK; +# +# With bug in place: acquire LOCK_mysql_create_table and +# wait in wait_if_global_read_lock(). +connection con2; +send DROP DATABASE mysqltest_1; +--sleep 1 +# +# With bug in place: try to acquire LOCK_mysql_create_table... +# When fixed: Reject dropping db because of the read lock. +connection con1; +--error ER_CANT_UPDATE_WITH_READLOCK +DROP DATABASE mysqltest_1; +UNLOCK TABLES; +# +connection con2; +reap; +# +connection default; +disconnect con1; +disconnect con2; +# This must have been dropped by connection 2 already, +# which waited until the global read lock was released. +--error ER_DB_DROP_EXISTS +DROP DATABASE mysqltest_1; + |