Lock Wait Timeout Exceeded
A database query waited too long for a lock held by another transaction.
Explanation
Lock wait timeout exceeded occurs when a transaction waits longer than the configured timeout period to acquire a lock held by another transaction. Unlike a deadlock (where both transactions block each other), this is a one-way wait - one transaction is holding a lock and the other is waiting for it. The waiting transaction is rolled back after the timeout. Common causes include long-running transactions, missing indexes causing table-level locks, and high-concurrency scenarios.
Common Causes
- Long-running transactions holding locks
- Missing indexes causing table locks
- High-concurrency write operations
- Lock escalation from row to table
- Transaction timeout too short
Solution
Identify and optimize long-running transactions that hold locks too long. Add proper database indexes to reduce lock scope. Use SELECT ... FOR UPDATE sparingly. Implement optimistic locking for high-concurrency scenarios. Increase innodb_lock_wait_timeout in MySQL if appropriate (default is 50 seconds). Monitor active transactions with SHOW ENGINE INNODB STATUS. Break large transactions into smaller ones. Use queue-based processing for write-heavy operations.
Code Example
// Long transaction holding a lock
DB::beginTransaction();
User::where('id', 1)->update(['status' => 'active']);
// ... long processing ...
// Another query tries to update same row - TIMEOUT!
DB::commit();
// Fix: keep transactions short
DB::beginTransaction();
User::where('id', 1)->update(['status' => 'active']);
DB::commit(); // commit immediately
// Monitor locks in MySQL
SHOW ENGINE INNODB STATUS;
SELECT * FROM information_schema.innodb_locks;
SELECT * FROM information_schema.innodb_trx;
// Increase timeout (MySQL)
SET GLOBAL innodb_lock_wait_timeout = 120;
// Or in my.cnf: innodb_lock_wait_timeout = 120
// Use optimistic locking in Eloquent
class User extends Model
{
use OptimisticLocking;
// Adds 'version' column for conflict detection
}Error Information
Language
php
Difficulty
Advanced
Views
13
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