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Bug#25422 (Hang with log tables)
Bug 17876 (Truncating mysql.slow_log in a SP after using cursor locks the
thread)
Bug 23044 (Warnings on flush of a log table)
Bug 29129 (Resetting general_log while the GLOBAL READ LOCK is set causes
a deadlock)
Prior to this fix, the server would hang when performing concurrent
ALTER TABLE or TRUNCATE TABLE statements against the LOG TABLES,
which are mysql.general_log and mysql.slow_log.
The root cause traces to the following code:
in sql_base.cc, open_table()
if (table->in_use != thd)
{
/* wait_for_condition will unlock LOCK_open for us */
wait_for_condition(thd, &LOCK_open, &COND_refresh);
}
The problem with this code is that the current implementation of the
LOGGER creates 'fake' THD objects, like
- Log_to_csv_event_handler::general_log_thd
- Log_to_csv_event_handler::slow_log_thd
which are not associated to a real thread running in the server,
so that waiting for these non-existing threads to release table locks
cause the dead lock.
In general, the design of Log_to_csv_event_handler does not fit into the
general architecture of the server, so that the concept of general_log_thd
and slow_log_thd has to be abandoned:
- this implementation does not work with table locking
- it will not work with commands like SHOW PROCESSLIST
- having the log tables always opened does not integrate well with DDL
operations / FLUSH TABLES / SET GLOBAL READ_ONLY
With this patch, the fundamental design of the LOGGER has been changed to:
- always open and close a log table when writing a log
- remove totally the usage of fake THD objects
- clarify how locking of log tables is implemented in general.
See WL#3984 for details related to the new locking design.
Additional changes (misc bugs exposed and fixed):
1)
mysqldump which would ignore some tables in dump_all_tables_in_db(),
but forget to ignore the same in dump_all_views_in_db().
2)
mysqldump would also issue an empty "LOCK TABLE" command when all the tables
to lock are to be ignored (numrows == 0), instead of not issuing the query.
3)
Internal errors handlers could intercept errors but not warnings
(see sql_error.cc).
4)
Implementing a nested call to open tables, for the performance schema tables,
exposed an existing bug in remove_table_from_cache(), which would perform:
in_use->some_tables_deleted=1;
against another thread, without any consideration about thread locking.
This call inside remove_table_from_cache() was not required anyway,
since calling mysql_lock_abort() takes care of aborting -- cleanly -- threads
that might hold a lock on a table.
This line (in_use->some_tables_deleted=1) has been removed.
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| .. | ||
| extra | ||
| include | ||
| lib | ||
| misc | ||
| ndb | ||
| r | ||
| std_data | ||
| suite | ||
| t | ||
| create-test-result | ||
| fix-result | ||
| install_test_db.sh | ||
| Makefile.am | ||
| mysql-stress-test.pl | ||
| mysql-test-run-shell.sh | ||
| mysql-test-run.pl | ||
| purify.supp | ||
| README | ||
| README.gcov | ||
| README.stress | ||
| resolve-stack | ||
| valgrind.supp | ||
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