# Pessimistic Lock

![left](./student-guide/diagram/PessimisticLocking_en_001_20220515.png)

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Let's review the pessimistic locking implement principle mentioned earlier. In the prwrite phase, we need to write the placeholder for the lock information to the region of the leader role and other follower roles. These operations are completed before the prewrite step is completed. As a result, both the network and IO are stressful.