MYSQL DEADLOCK MULTITHREADED APPLICATION HOW TO
I will show some tips on how to collect the missed statements.
What are missed are the earlier statements that might have really acquired the locks. Also it only shows the last statement executed in the two transactions, and locks from the two transactions that created the cycle. How to diagnose a MySQL deadlockĪ MySQL deadlock could involve more than two transactions, but the LATEST DETECTED DEADLOCK section only shows the last two transactions. 1213) and handle it by retrying the transaction. With MySQL 5.6, you can enable a new variable innodb_print_all_deadlocks to have all deadlocks in InnoDB recorded in mysqld error log.īefore and above all diagnosis, it is always an important practice to have the applications catch deadlock error (MySQL error no. For more information on using pt-deadlock-logger, see this post. But with Percona Toolkit’s pt-deadlock-logger you can have deadlock information retrieved from SHOW ENGINE INNODB STATUS at a given interval and saved to a file or table for late diagnosis. Though an occasional deadlock is not something to worry about, frequent occurrences call for attention.īefore MySQL 5.6, only the latest deadlock can be reviewed using SHOW ENGINE INNODB STATUS command. It uses a metric to pick the easiest transaction to rollback.
InnoDB automatically detects transaction deadlocks, rollbacks a transaction immediately and returns an error. In a transaction system, deadlocks are a fact of life and not completely avoidable. A deadlock in MySQL happens when two or more transactions mutually hold and request for locks, creating a cycle of dependencies.
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