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Percona Software for MySQL Documentation

Configure Systemd TimeoutStartSec

If your MySQL service takes too long to start, it might be due to a large buffer pool or a significant amount of data synchronization. You can either increase the MySQL service TimeoutStartSec option or disable the option.

We recommend that yoou treat TimeoutStartSec as a diagnostic and management tool, not as a permanent fix for underlying performance problems.

The following are the benefits of using TimeoutStartSec:

  • Prevents services from hanging indefinitely during startup

  • Provides controlled startup time management

  • Stops runaway processes from consuming system resources

  • Offers flexibility in handling complex service initialization

  • Helps detect and manage slow-starting database services

  • Enables precise control over service launch duration

The following are the potential drawbacks of using TimeoutStartSec:

  • Arbitrarily low settings might interrupt legitimate slow startups

  • Requires careful tuning for different system configurations

  • Can mask underlying performance or configuration issues

  • Might hide complex initialization problems

  • Demands ongoing monitoring and adjustment

You should test and use TimeoutStartSec in the following situations:

  • Large databases with extensive initialization requirements

  • Servers with limited resources

  • Complex clustered database environments

  • Systems with significant data synchronization needs

Use the following techniques to test the option:

  • Start with generous timeout values

  • Gradually reduce timeout as you understand your system’s behavior

  • Monitor service startup patterns

  • Use logging to understand initialization bottlenecks

  • Test configuration changes in staging environments

Check the current timeout

Check the current timeout with the following:

$ systemctl show mysql.service -p TimeoutStartUSec
Expected output 
TimeoutStartUSec=10min

Edit the command

The following command opens an editor:

$ sudo systemctl edit mysql.service

In the text editor, overwrite the TimeoutStartSec configuration:

[Service]
TimeoutStartSec=900s

For the edited change to take effect, run the following command:

$ sudo systemctl daemon-reload

After reloading the system, the value is 15 minutes.

Expected output 
TimeoutStartUSec=15min

Disable the option

To disable the option, change the value to 0:

[Service]
TimeoutStartSec=0

For the edited change to take effect, run the following command:

$ sudo systemctl daemon-reload

After reloading the system, the option is disabled.

Expected output 
TimeoutStartUSec=infinity

Verify the change

After systemctl has been reloaded, verify your change. 

$ systemctl show mysql.service -p TimeoutStartUSec

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Last update: 2024-12-09