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Fixed Bug#11756013 (formerly known as bug#47870):

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BOGUS "THE TABLE MYSQL.PROC IS MISSING,..."

There was a race condition between loading a stored routine
(function/procedure/trigger) specified by fully qualified name
SCHEMA_NAME.PROC_NAME and dropping the stored routine database.

The problem was that there is a window for race condition when one server
thread tries to load a stored routine being executed and the other thread
tries to drop the stored routine schema.

This condition race window exists in implementation of function
mysql_change_db() called by db_load_routine() during loading of stored
routine to cache. Function mysql_change_db() calls check_db_dir_existence()
that might failed because specified database was dropped during concurrent
execution of DROP SCHEMA statement. db_load_routine() calls mysql_change_db()
with flag 'force_switch' set to 'true' value so when referenced db is not found
then my_error() is not called and function mysql_change_db() returns ok.
This shadows information about schema opening error in db_load_routine().
Then db_load_routine() makes attempt to parse stored routine that is failed.
This makes to return error to sp_cache_routines_and_add_tables_aux() but since
during error generation a call to my_error wasn't made and hence
THD::main_da wasn't set we set the generic "mysql.proc table corrupt" error
when running sp_cache_routines_and_add_tables_aux().

The fix is to install an error handler inside db_load_routine() for
the mysql_op_change_db() call, and check later if the ER_BAD_DB_ERROR
was caught.
This commit is contained in:
Dmitry Shulga
2011-06-23 20:41:04 +07:00
parent b3696af2e6
commit 07056eb984
4 changed files with 87 additions and 3 deletions
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14
mysql-test/r/sp_sync.result
View File

@@ -1,4 +1,4 @@
Tests of syncronization of stored procedure execution.
Tests of synchronization of stored procedure execution.
#
# Bug#48157: crash in Item_field::used_tables
#
@@ -20,4 +20,16 @@ SET DEBUG_SYNC = 'now SIGNAL go';
# code, this test statement will hang.
DROP TABLE t1, t2;
DROP PROCEDURE p1;
#
# test for bug#11756013
#
DROP SCHEMA IF EXISTS s1;
CREATE SCHEMA s1;
CREATE PROCEDURE s1.p1() BEGIN END;
SET DEBUG_SYNC='before_db_dir_check SIGNAL check_db WAIT_FOR dropped_schema';
CALL s1.p1;
SET DEBUG_SYNC='now WAIT_FOR check_db';
DROP SCHEMA s1;
SET DEBUG_SYNC='now SIGNAL dropped_schema';
ERROR 42000: Unknown database 's1'
SET DEBUG_SYNC = 'RESET';

31
mysql-test/t/sp_sync.test
View File

@@ -1,7 +1,10 @@
# This test should work in embedded server after mysqltest is fixed
-- source include/not_embedded.inc
--echo Tests of syncronization of stored procedure execution.
# Save the initial number of concurrent sessions
--source include/count_sessions.inc
--echo Tests of synchronization of stored procedure execution.
--source include/have_debug_sync.inc
@@ -54,5 +57,31 @@ connection default;
DROP TABLE t1, t2;
DROP PROCEDURE p1;
--echo #
--echo # test for bug#11756013
--echo #
--disable_warnings
DROP SCHEMA IF EXISTS s1;
--enable_warnings
CREATE SCHEMA s1;
CREATE PROCEDURE s1.p1() BEGIN END;
connect (con3, localhost, root);
SET DEBUG_SYNC='before_db_dir_check SIGNAL check_db WAIT_FOR dropped_schema';
--send CALL s1.p1
connection default;
SET DEBUG_SYNC='now WAIT_FOR check_db';
DROP SCHEMA s1;
SET DEBUG_SYNC='now SIGNAL dropped_schema';
connection con3;
--error ER_BAD_DB_ERROR
--reap
connection default;
disconnect con3;
SET DEBUG_SYNC = 'RESET';
# Wait till we reached the initial number of concurrent sessions
--source include/wait_until_count_sessions.inc