diff options
Diffstat (limited to 'mysql-test/r/mdl_sync.result')
| -rw-r--r-- | mysql-test/r/mdl_sync.result | 95 |
1 files changed, 94 insertions, 1 deletions
diff --git a/mysql-test/r/mdl_sync.result b/mysql-test/r/mdl_sync.result index f8b8d3f9d56..67d778211dd 100644 --- a/mysql-test/r/mdl_sync.result +++ b/mysql-test/r/mdl_sync.result @@ -1765,6 +1765,7 @@ drop tables t1, t2; # locking subsystem. # drop tables if exists t0, t1, t2, t3, t4, t5; +set debug_sync= 'RESET'; create table t1 (i int); create table t2 (j int); create table t3 (k int); @@ -1943,6 +1944,98 @@ commit; # Reap ALTER TABLE ... RENAME. drop table t2; # +# Test that in situation when MDL subsystem detects a deadlock +# but it turns out that it can be resolved by backing-off locks +# acquired by one of participating transactions (which is +# possible when one of transactions consists only of currently +# executed statement, e.g. in autocommit mode) no error is +# reported. +# +create table t1 (i int); +create table t2 (j int); +# Ensure that the below SELECT stops once it has acquired metadata +# lock on table 't2'. +set debug_sync= 'after_open_table_mdl_shared SIGNAL locked WAIT_FOR finish'; +# Sending: +select * from t2, t1; +# +# Switching to connection 'deadlock_con1'. +# Wait till SELECT acquires MDL on 't2' and starts waiting for signal. +set debug_sync= 'now WAIT_FOR locked'; +# Sending: +lock tables t1 write, t2 write; +# +# Switching to connection 'deadlock_con2'. +# Wait until LOCK TABLES acquires SNRW lock on 't1' and is blocked +# while trying to acquire SNRW lock on 't1'. +# Resume SELECT execution, this should eventually unblock LOCK TABLES. +set debug_sync= 'now SIGNAL finish'; +# +# Switching to connection 'deadlock_con1'. +# Reaping LOCK TABLES. +unlock tables; +# +# Switching to connection 'default'. +# Reaping SELECT. It succeed and not report ER_LOCK_DEADLOCK error. +j i +drop tables t1, t2; +# +# Test coverage for situation in which a race has happened +# during deadlock detection process which led to unwarranted +# ER_LOCK_DEADLOCK error. +# +create table t1 (i int); +# Ensure that ALTER waits once it has acquired SNW lock. +set debug_sync='after_open_table_mdl_shared SIGNAL parked1 WAIT_FOR go1'; +# Sending: +alter table t1 add column j int; +# +# Switching to connection 'deadlock_con1'. +# Wait till ALTER acquires SNW lock and stops. +set debug_sync='now WAIT_FOR parked1'; +# Ensure that INSERT is paused once it detects that there is +# a conflicting metadata lock so it has to wait, but before +# deadlock detection is run. +set debug_sync='mdl_acquire_lock_wait SIGNAL parked2 WAIT_FOR go2'; +# Sending: +insert into t1 values (); +# +# Switching to connection 'deadlock_con2'. +# Wait till INSERT is paused. +set debug_sync='now WAIT_FOR parked2'; +# Resume ALTER execution. Eventually it will release its +# metadata lock and INSERT's request for SW lock will be +# satisified. +set debug_sync='now SIGNAL go1'; +# +# Switching to connection 'default'. +# Reaping ALTER TABLE. +# Add a new request for SNW lock to waiting graph. +# Sending: +alter table t1 drop column j; +# +# Switching to connection 'deadlock_con2'. +# Wait until ALTER is blocked. +# Resume INSERT so it can start deadlock detection. +# +# At this point there is a discrepancy between the fact that INSERT's +# SW lock is already satisfied, but INSERT's connection is still +# marked as waiting for it. Looking for a loop in waiters graph +# without additional checks has detected a deadlock (INSERT waits +# for SW lock; which is not granted because of pending SNW lock from +# ALTER; which waits for active SW lock from INSERT). Since requests +# for SW and SNW locks have same weight ALTER was selected as a victim +# and ended with ER_LOCK_DEADLOCK error. +set debug_sync='now SIGNAL go2'; +# +# Switching to connection 'deadlock_con1'. +# Reaping INSERT. +# +# Switching to connection 'default'. +# Reaping ALTER. It should succeed and not produce ER_LOCK_DEADLOCK. +drop table t1; +set debug_sync= 'RESET'; +# # Test for bug #46748 "Assertion in MDL_context::wait_for_locks() # on INSERT + CREATE TRIGGER". # @@ -2175,7 +2268,7 @@ alter table t1 add column e int, rename to t2;; # # Switching to connection 'default'. set debug_sync='now WAIT_FOR alter_table_locked'; -set debug_sync='before_open_table_wait_refresh SIGNAL alter_go'; +set debug_sync='mdl_acquire_lock_wait SIGNAL alter_go'; # The below statement should get ER_LOCK_DEADLOCK error # (i.e. it should not allow ALTER to proceed, and then # fail due to 't1' changing its name to 't2'). |