mariadb/mysql-test
Jon Olav Hauglid c7bcb28f0c Bug #49988 MDL deadlocks with mysql_create_db, reload_acl_and_cache
This was a deadlock between LOCK TABLES/CREATE DATABASE in one connection
and DROP DATABASE in another. It only happened if the table locked by 
LOCK TABLES was in the database to be dropped. The deadlock is similar
to the one in Bug#48940, but with LOCK TABLES instead of an active
transaction.

The order of events needed to trigger the deadlock was:
1) Connection 1 locks table db1.t1 using LOCK TABLES. It will now
have a metadata lock on the table name.
2) Connection 2 issues DROP DATABASE db1. This will wait inside
the MDL subsystem for the lock on db1.t1 to go away. While waiting, it
will hold the LOCK_mysql_create_db mutex.
3) Connection 1 issues CREATE DATABASE (database name irrelevant).
This will hang trying to lock the same mutex. Since this is the connection
holding the metadata lock blocking Connection 2, we have a deadlock.

This deadlock would also happen for earlier trees without MDL, but 
there DROP DATABASE would wait for a table to be removed from the
table definition cache.

This patch fixes the problem by prohibiting CREATE DATABASE in LOCK TABLES
mode. In the example above, this prevents Connection 1 from hanging trying
to get the LOCK_mysql_create_db mutex. Note that other commands that use
LOCK_mysql_create_db (ALTER/DROP DATABASE) are already prohibited in 
LOCK TABLES mode.

Incompatible change: CREATE DATABASE is now disallowed in LOCK TABLES mode.

Test case added to schema.test.


mysql-test/t/drop.test:
  Updates the test for Bug#21216 by swapping the order of CREATE DATABASE
  and LOCK TABLES. This is now needed as CREATE DATABASE is prohibited in
  LOCK TABLES mode.
mysql-test/t/schema.test:
  Test case for Bug#49988 added.
  Also fixes a problem with the test for Bug#48940 where the result 
  would differ for embedded server.
2010-01-12 16:15:21 +01:00
..
collections Manual resolving for the following files 2009-12-01 21:07:18 +02:00
extra Merge next-mr -> next-4284. 2009-12-15 22:59:07 +03:00
include Implementation of simple deadlock detection for metadata locks. 2009-12-30 20:53:30 +03:00
lib Merge next-mr -> next-4284. 2009-12-16 11:33:54 +03:00
r Bug #49988 MDL deadlocks with mysql_create_db, reload_acl_and_cache 2010-01-12 16:15:21 +01:00
std_data Backporting Bug#37129 LDML lacks <i> rule 2009-11-09 13:45:40 +04:00
suite Apply and review: 2009-12-29 15:19:05 +03:00
t Bug #49988 MDL deadlocks with mysql_create_db, reload_acl_and_cache 2010-01-12 16:15:21 +01:00
Makefile.am Apply patch from bug#46834 to install the test suite in RPMs. 2009-08-21 13:58:33 +02:00
mysql-stress-test.pl Checking in new version of 'mysql-stress-test.pl that was used for the last few month 2009-09-25 08:27:55 -07:00
mysql-test-run.pl Auto merge from 5.1-rep-semisync 2009-12-05 10:28:53 +08:00
purify.supp
README
README.gcov
README.stress
valgrind.supp fixed a typo in valgrind.supp 2009-09-25 14:52:41 +03:00

This directory contains a test suite for the MySQL daemon. To run
the currently existing test cases, simply execute ./mysql-test-run in
this directory. It will fire up the newly built mysqld and test it.

Note that you do not have to have to do "make install", and you could
actually have a co-existing MySQL installation. The tests will not
conflict with it.

All tests must pass. If one or more of them fail on your system, please
read the following manual section for instructions on how to report the
problem:

http://dev.mysql.com/doc/mysql/en/mysql-test-suite.html

If you want to use an already running MySQL server for specific tests,
use the --extern option to mysql-test-run. Please note that in this mode,
the test suite expects you to provide the names of the tests to run.
For example, here is the command to run the "alias" and "analyze" tests
with an external server:

mysql-test-run --extern alias analyze

To match your setup, you might also need to provide --socket, --user, and
other relevant options.

With no test cases named on the command line, mysql-test-run falls back
to the normal "non-extern" behavior. The reason for this is that some
tests cannot run with an external server.


You can create your own test cases. To create a test case, create a new
file in the t subdirectory using a text editor. The file should have a .test
extension. For example:

 xemacs t/test_case_name.test

 In the file, put a set of SQL statements that create some tables,
 load test data, and run some queries to manipulate it.

 We would appreciate it if you name your test tables t1, t2, t3 ... (to not
 conflict too much with existing tables).

 Your test should begin by dropping the tables you are going to create and
 end by dropping them again.  This ensures that you can run the test over
 and over again.
 
 If you are using mysqltest commands (like result file names) in your
 test case, you should create the result file as follows:

 mysql-test-run --record test_case_name

 or

 mysqltest --record < t/test_case_name.test

 If you only have a simple test cases consisting of SQL statements and
 comments, you can create the test case in one of the following ways:

 mysql-test-run --record test_case_name

 mysql test < t/test_case_name.test > r/test_case_name.result

 mysqltest --record --record-file=r/test_case_name.result < t/test_case_name.test

 When this is done, take a look at r/test_case_name.result
 - If the result is incorrect, you have found a bug. In this case, you should
   edit the test result to the correct results so that we can verify
   that the bug is corrected in future releases.

To submit your test case, put your .test file and .result file(s) into
a tar.gz archive, add a README that explains the problem, ftp the 
archive to ftp://support.mysql.com/pub/mysql/secret/ and send a mail
to bugs@lists.mysql.com