def book = Book.get(1)
book.lock()lock
Purpose
The lock method obtains a pessimistic lock using an SQL select … for update.
Examples
Description
The lock method obtains a pessimistic lock on an instance, locking the row in the database with select … for update. The lock method is equivalent to using Hibernate’s LockMode.UPGRADE in combination with the http://docs.jboss.org/hibernate/orm/current/javadocs/org/hibernate/Session#lock(java/lang/Object, org/hibernate/LockMode).html[lock] method.
The lock is automatically released when the transaction commits. In Grails this is typically after an action has finished executing.
Refer to the section on Optimistic and Pessimistic locking in the user guide for info.