mirror of
https://github.com/MariaDB/server.git
synced 2025-11-02 11:56:13 +01:00
The MDL_BACKUP_COMMIT lock used in handler.cc:ha_commit_trans() that is used to block commits as part of FLUSH TABLES WITH READ LOCK and BACKUP STAGE BLOCK_COMMIT can have a notable performance impact We need the commit block to be able to ensure consistent backups. The purpose of this commit is to instead of taking an expensive MDL lock, to protect each commit for a unlikely backup or FTWRL, we would instead add markers to threads that are doing a commit and when BLOCK_COMMIT or a FTWRL lock is used we would do slightly more work to ensure that all threads are taking MDL locks before taking the requested lock. When backup and FTRWL are not running we are now incrementing a global variable and setting a marker in the THD to signal that the thread is in the 'protected commit code block'. When FTWRL or BACKUP STAGE START is executed we enable MDL locking for commits and wait until all threads are outside of the protected block before continuing. When FTWRL and BACKUP STAGE end, we mark that MDL protecting is not anymore needed. The effect is that we change a MDL lock to two atomic increments and two memory assignments and one extra if. This speeds up commits but causes FTWRL and BACKUP STAGE START to be slower to start as they have to wait for active commits to complete. Most of the new logic can be found in the functions: enable_backup_commit_locks(), protect_against_backup() and unprotect_against_backup(). Other things: - The changes in the tests where because BACKUP STAGE START will now block if there are threads inside the 'protected commit block'. Before we waited in the test for BACKUP STAGE BLOCK COMMIT. I have now changed the tests to either wait for BACKUP STAGE START or by doing BACKUP STAGE START early and wait for BACKUP STAGE COMMIT. - Added MDL_request mdl_backup to THD to avoid initializing a new MDL_request for each commit and to simplify some code. This added 448 bytes to the THD. |
||
|---|---|---|
| .. | ||
| collections | ||
| include | ||
| lib | ||
| main | ||
| std_data | ||
| suite | ||
| asan.supp | ||
| CMakeLists.txt | ||
| dgcov.pl | ||
| lsan.supp | ||
| mariadb-stress-test.pl | ||
| mariadb-test-run.pl | ||
| mtr.out-of-source | ||
| purify.supp | ||
| README | ||
| README-gcov | ||
| README.stress | ||
| suite.pm | ||
| valgrind.supp | ||
This directory contains test suites for the MariaDB server. To run currently existing test cases, execute ./mysql-test-run in this directory. Some tests are known to fail on some platforms or be otherwise unreliable. In the file collections/smoke_test there is a list of tests that are expected to be stable. In general you do not have to have to do "make install", and you can have a co-existing MariaDB installation, the tests will not conflict with it. To run the tests in a source directory, you must do "make" first. In Red Hat distributions, you should run the script as user "mysql". The user is created with nologin shell, so the best bet is something like # su - # cd /usr/share/mysql-test # su -s /bin/bash mysql -c ./mysql-test-run This will use the installed MariaDB executables, but will run a private copy of the server process (using data files within /usr/share/mysql-test), so you need not start the mysqld service beforehand. You can omit --skip-test-list option if you want to check whether the listed failures occur for you. To clean up afterwards, remove the created "var" subdirectory, e.g. # su -s /bin/bash - mysql -c "rm -rf /usr/share/mysql-test/var" If tests fail on your system, please read the following manual section for instructions on how to report the problem: https://mariadb.com/kb/en/reporting-bugs 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, you are expected to provide 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 socket=/tmp/mysql.sock alias analyze To match your setup, you might need to provide other relevant options. With no test names on the command line, mysql-test-run will attempt to execute the default set of tests, which will certainly fail, because many tests cannot run with an external server (they need to control the options with which the server is started, restart the server during execution, etc.) You can create your own test cases. To create a test case, create a new file in the main 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. 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 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 case consisting of SQL statements and comments, you can create the result file 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 --database test --result-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. If you want to submit your test case you can send it to developers@lists.mariadb.org or attach it to a bug report on http://mariadb.org/jira/. If the test case is really big or if it contains 'not public' data, then 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://ftp.mariadb.org/private and submit a report to https://mariadb.org/jira about it. The latest information about mysql-test-run can be found at: https://mariadb.com/kb/en/mariadb/mysqltest/ If you want to create .rdiff files, check https://mariadb.com/kb/en/mariadb/mysql-test-auxiliary-files/