Pessimistic Locking - bobocode-breskul/bibernate GitHub Wiki

Pessimistic Locking

Overview

Pessimistic locking is a concurrency control mechanism that is used to prevent conflicts when multiple transactions attempt to access the same data concurrently. Unlike optimistic locking, which proceeds with the assumption that a conflict is unlikely to happen and checks for conflicts before committing the transaction, pessimistic locking assumes that conflicts are likely to occur and locks the data before working with it. This approach is particularly useful in high-concurrency environments or in scenarios where data conflicts are common.

When to Use Pessimistic Locking

Pessimistic locking is most appropriate in scenarios where the cost of a conflict is high or where conflicts are frequent. Some common use cases include:

• Transactions that involve a long processing time.
• Applications with high contention for data, where multiple transactions frequently access the same records.
• Operations where the likelihood of data being changed by another transaction is high.

Implementing Pessimistic Locking in Bibernate

Bibernate supports pessimistic locking through its API, allowing developers to lock entities explicitly to prevent concurrent modifications. Here's how to use pessimistic locking with Bibernate:

1. Locking an Entity: To lock an entity pessimistically, Bibernate provides a method in the Session. You can specify the lock mode when retrieving an entity:

   Entity entity = session.findById(Entity.class, entityId, LockType.PESSIMISTIC_WRITE);
   

   This example demonstrates how to obtain an entity with a pessimistic write lock, ensuring that no other transactions can modify the data until the current transaction is completed.