a83c7ab1ea
Problem: ======== If a primary is shutdown during an active semi-sync connection during the period when the primary is awaiting an ACK, the primary hard kills the active communication thread and does not ensure the transaction was received by a replica. This can lead to an inconsistent replication state. Solution: ======== During shutdown, the primary should wait for an ACK or timeout before hard killing a thread which is awaiting a communication. We extend the `SHUTDOWN WAIT FOR SLAVES` logic to identify and ignore any threads waiting for a semi-sync ACK in phase 1. Then, before stopping the ack receiver thread, the shutdown is delayed until all waiting semi-sync connections receive an ACK or time out. The connections are then killed in phase 2. Notes: 1) There remains an unresolved corner case that affects this patch. MDEV-28141: Slave crashes with Packets out of order when connecting to a shutting down master. Specifically, If a slave is connecting to a master which is actively shutting down, the slave can crash with a "Packets out of order" assertion error. To get around this issue in the MTR tests, the primary will wait a small amount of time before phase 1 killing threads to let the replicas safely stop (if applicable). 2) This patch also fixes MDEV-28114: Semi-sync Master ACK Receiver Thread Can Error on COM_QUIT Reviewed By ============ Andrei Elkin <andrei.elkin@mariadb.com>
Code status:
ci.appveyor.com
MariaDB: drop-in replacement for MySQL
MariaDB is designed as a drop-in replacement of MySQL(R) with more features, new storage engines, fewer bugs, and better performance.
MariaDB is brought to you by the MariaDB Foundation and the MariaDB corporation. Please read the CREDITS file for details about the MariaDB Foundation, and who is developing MariaDB.
MariaDB is developed by many of the original developers of MySQL who now work for the MariaDB Corporation, the MariaDB Foundation and by many people in the community.
MySQL, which is the base of MariaDB, is a product and trademark of Oracle Corporation, Inc. For a list of developers and other contributors, see the Credits appendix. You can also run 'SHOW authors' to get a list of active contributors.
A description of the MariaDB project and a manual can be found at:
https://mariadb.com/kb/en/mariadb-vs-mysql-features/
https://mariadb.com/kb/en/mariadb-versus-mysql-compatibility/
https://mariadb.com/kb/en/library/new-and-old-releases/
As MariaDB is a full replacement of MySQL, the MySQL manual at http://dev.mysql.com/doc is generally applicable.
Help
More help is available from the Maria Discuss mailing list https://launchpad.net/~maria-discuss and the #maria IRC channel on Freenode.
Live QA for beginner contributors
MariaDB has a dedicated time each week when we answer new contributor questions live on Zulip and IRC. From 8:00 to 10:00 UTC on Mondays, and 10:00 to 12:00 UTC on Thursdays, anyone can ask any questions they’d like, and a live developer will be available to assist.
New contributors can ask questions any time, but we will provide immediate feedback during that interval.
Licensing
NOTE:
MariaDB is specifically available only under version 2 of the GNU General Public License (GPLv2). (I.e. Without the "any later version" clause.) This is inherited from MySQL. Please see the README file in the MySQL distribution for more information.
License information can be found in the COPYING file. Third party license information can be found in the THIRDPARTY file.
Bug Reports
Bug and/or error reports regarding MariaDB should be submitted at: https://jira.mariadb.org
For reporting security vulnerabilities see: https://mariadb.org/about/security-policy/
Bugs in the MySQL code can also be submitted at: https://bugs.mysql.com
The code for MariaDB, including all revision history, can be found at: https://github.com/MariaDB/server