# Memory Pessimistic Lock
__*Memory pessimistic lock*__
__*In-Memory Pessimistic Locking*__

![left](./student-guide/diagram/InMemoryPessimisticLocking_en_001_20220515.png)

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When the memory pessimistic lock is turned on, the lock information is only stored in memory, not written to disk, or multiple replica via raft, as long as it exists in the region leader. The lock information is written to memory, and the delay is minimal compared to writing multiple replica via raft.