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Description

Error 3572 indicates that your SQL statement attempted to acquire a lock on a resource (like a row or table) but failed to do so immediately because the `NOWAIT` option was active. This means another transaction already held the lock, and instead of waiting, your statement was aborted.

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Error Message

Statement aborted because lock(s) could not be acquired immediately and NOWAIT is set.

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Known Causes

3 known causes

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Conflicting Transaction Holds Lock

A different active transaction is currently holding a lock on the specific resource that your statement attempted to modify or access, preventing immediate acquisition.

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Explicit NOWAIT Clause Used

Your SQL statement explicitly included the `NOWAIT` clause, instructing MySQL to abort the operation immediately if the required lock cannot be acquired at once, rather than waiting.

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High Database Contention

In environments with many concurrent transactions attempting to access or modify the same data, lock contention increases, making immediate lock acquisition challenging.

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Solutions

4 solutions available

1. Temporarily Increase Lock Timeout easy

Adjust the lock wait timeout to allow for longer lock acquisition.

1

Connect to your MySQL server using a client like `mysql` or MySQL Workbench.

2

Set the `innodb_lock_wait_timeout` variable to a higher value. A common starting point is 50 seconds (default is 50, but can be lower). You can set it globally for the current session or for all sessions.

SET GLOBAL innodb_lock_wait_timeout = 100;
-- Or for the current session:
SET SESSION innodb_lock_wait_timeout = 100;

3

Re-run the statement that caused the error.

4

Consider making this change permanent by adding `innodb_lock_wait_timeout = 100` to your `my.cnf` or `my.ini` configuration file and restarting the MySQL server.

2. Identify and Resolve Locking Transactions medium

Find the transaction holding the lock and resolve it.

1

Connect to your MySQL server and execute the following query to identify active transactions and their status.

SHOW ENGINE INNODB STATUS;

2

Examine the output of `SHOW ENGINE INNODB STATUS` under the `TRANSACTIONS` section. Look for long-running transactions or transactions that are holding locks on the resources your statement needs.

3

Identify the `trx id` of the blocking transaction. You can also use `information_schema.INNODB_LOCKS` and `information_schema.INNODB_LOCK_WAITS` for more detailed information.

SELECT * FROM information_schema.INNODB_LOCKS;
SELECT * FROM information_schema.INNODB_LOCK_WAITS;

4

Once the blocking transaction is identified, determine if it can be safely terminated. If it's a legitimate, but long-running, process, you might need to wait for it to complete. If it's an orphaned or stuck transaction, you can kill it.

KILL <thread_id>;

5

To find the `thread_id` associated with a transaction, you can join `information_schema.INNODB_TRX` with `information_schema.PROCESSLIST`.

SELECT t.trx_id, p.ID as thread_id, p.COMMAND, p.TIME, p.INFO FROM information_schema.INNODB_TRX t JOIN information_schema.PROCESSLIST p ON t.trx_mysql_thread_id = p.ID WHERE t.trx_state = 'RUNNING';

6

Re-run your original statement after the blocking transaction has been resolved.

3. Optimize Queries and Indexes advanced

Improve query performance to reduce lock contention.

1

Analyze the queries that are frequently causing lock contention. Use `EXPLAIN` to understand the execution plan of these queries.

EXPLAIN SELECT ... FROM ... WHERE ...;

2

Identify missing or inefficient indexes. Ensure that columns used in `WHERE`, `JOIN`, and `ORDER BY` clauses are properly indexed.

SHOW INDEX FROM your_table_name;

3

Add appropriate indexes if needed. For example, if a query frequently filters on `user_id`, create an index on that column.

CREATE INDEX idx_user_id ON your_table_name (user_id);

4

Refactor queries to be more efficient. Avoid full table scans, use appropriate join types, and minimize the amount of data being processed.

5

Consider using `SELECT ... FOR UPDATE` or `SELECT ... LOCK IN SHARE MODE` judiciously. If your application logic requires explicit locking, ensure it's done efficiently and released promptly. The `NOWAIT` clause indicates that explicit locking might be in use.

6

Monitor slow queries using the MySQL slow query log to proactively identify and address performance bottlenecks.

4. Disable NOWAIT (if appropriate) easy

Remove the NOWAIT clause if immediate lock acquisition is not strictly required.

1

Locate the SQL statement in your application code or in a script that is causing the error. Identify the `NOWAIT` clause.

SELECT ... FROM ... FOR UPDATE NOWAIT;

2

Remove the `NOWAIT` clause from the statement.

SELECT ... FROM ... FOR UPDATE;

3

Deploy the updated code or script. This will allow the statement to wait for the lock to be released instead of failing immediately.

4

Understand the implications of removing `NOWAIT`. Your application will now block until the lock is acquired, which might affect its responsiveness. Ensure this is acceptable for your use case.

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Related Errors

5 related errors

MySQL Error 3572: Lock Acquisition Failure with NOWAIT