MDEV-30307 KILL command inside a transaction causes problem for galer… #2397
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…a replication Added new test scenario in galera.galera_bf_kill test to make the issue surface, The tetst scenario has a multi statement transaction containing a KILL command. When the KILL is submitted, another transaction is replicated, which causes BF abort for the KILL command processing. Handling BF abort rollback while executing KILL command causes node hanging, in this scenario. sql_kill() and sql_kill_user() functions have now fix, to perform implicit commit before starting the KILL command execution. BEcause of the implicit commit, the KILL execution will not happen inside transaction context anymore.
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…a replication
Description
If KILL command is submitted inside a transaction, galera replication may have problems to deal with cluster conflict resolving. One failure scenario is if the transaction (submitting the KILL command) is it self a victim of BF aborting. Eternal hang of the node may result.
sql_kill() and sql_kill_user() functions have now fix, to perform implicit commit before starting the KILL command execution. Because of the implicit commit, the KILL execution will not happen inside transaction context anymore.
How can this PR be tested?
Added new test scenario in galera.galera_bf_kill test to make the issue surface, The test scenario has a multi statement transaction containing a KILL command. When the KILL is submitted, another transaction is replicated, which causes BF abort for the KILL command processing. Handling BF abort rollback while executing KILL command causes node hanging, in this scenario.
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Basing the PR against the correct MariaDB version
Backward compatibility
This change is deviation of stand-alone MariaDB behavior. With the fix, the transaction will be implicitly committed before the KILL command execution.