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The query cache protected all operations with one exclusive lock (m_cache_lock_status, guarded by structure_guard_mutex). This serialized every lookup, even though a lookup mainly reads the query cache structures. Added a new global variable, query_cache_use_rw_lock (default OFF). When set, send_result_to_client() takes a shared (read) lock instead of an exclusive one, which allows lookups to run concurrently. Having it as an option makes it possible to benchmark both alternatives with the same binary and then decide which one to keep. Implementation: - try_lock() has a new 'read_lock' argument. The new inline function try_read_lock() sets it from query_cache_use_rw_lock. - Readers are counted in m_readers and leave m_cache_lock_status as UNLOCKED. Writers wait until m_readers is 0 and are counted in m_waiting_writers. Waiting writers have priority over new readers, which ensures that invalidations are not starved by cache hits. - Readers wait on the new COND_cache_read_lock. wake_up_waiters() wakes one waiting writer, or all waiting readers if there is none. - unlock() is split into unlock() and unlock_internal(). The kind of lock to release is deduced from m_cache_lock_status, so none of the unlock() callers had to be changed. - send_result_to_client() updates the query list and the statistics under structure_guard_mutex when it only holds a read lock. With a write lock this is done as before, without taking the mutex. - If an engine requests invalidation during a lookup done with a read lock, the table key is copied and the invalidation is done after the lock is released, as invalidation requires a write lock. - Added the DEBUG_SYNC point "in_query_cache_hit" used by the new test. With query_cache_use_rw_lock=0 the code works as before. Did a simple sysbench run with 64 threads and 200000 simple select queries, all served from query cache. query_cache_use_rw_lock=1 gave a 2.25x speedup. The difference to an unmodied MariaDB version for the same test is 2.3 x faster. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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 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/mariadb-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/mariadb-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/mariadb-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/docs/general-resources/community/community/bug-tracking/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: # mariadb-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: # mariadb-test-run --record test_case_name or # mariadb-test --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: # mariadb-test-run --record test_case_name # mariadb test < t/test_case_name.test > r/test_case_name.result # mariadb-test --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/docs/server/clients-and-utilities/testing-tools/mariadb-test If you want to create .rdiff files, check https://mariadb.com/docs/server/clients-and-utilities/testing-tools/mariadb-test/mariadb-test-auxiliary-files