Removing a System Lock

As part of normal operation when a Nominode is upgraded or rebooted, a system lock is created in the system_lock table in the back-end database for your Nominode. The system lock is used to ensure that your Tasks and Sequences don't run before all of the pieces of the Nominode software are properly loaded. However, there are scenarios where entries in the system_lock table are not properly removed, especially if an upgrade or reboot is interrupted before it has had a chance to fully complete.

How to Determine If a System Lock Exists

If you see the following text in the Logs section of the Status page of your Nominode:

Exception: A system lock in place preventing new sequences from being executed.

That is a strong indicator that an entry exists in your system_lock table. If your Nominode is not in the midst of rebooting or being upgraded, it may be necessary to manually remove all entries in order to restore normal execution for your Tasks and Sequences. You can also directly inspect the contents of your Nominode's system_lock table to determine if any rows exist within it.

Adjusting a System Lock from the Nominode Status Page

You can enable or disable Task executions from the Status page of your Nominode:

Toggling the Lock Executions button here will create or purge entries in the system_lock table.

Accessing a Nominode's system_lock Table

Information needed to access the back-end database used by your Nominode can be found in the [DATABASE] section of the config.ini file in the config folder under the folder where your Nominode software is installed. It will look like this:

[DATABASE]
hostname = <host>
port = <port>
username = <user>
password = <password>
database = <database>

Connect to the database using any SQL Client and execute this SQL statement:

SELECT * FROM system_lock;

If a row entry is returned, then a system lock exists.

Manually Removing System Locks

To remove the system lock from your Nominode, execute this SQL statement:

DELETE FROM system_lock;

Do not do this if your Nominode is in the midst of a reboot or upgrade. Allowing a Task or Sequence to execute before all portions of a Nominode has loaded can lead to unexpected and undesired results.