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This article will explain in detail what is the deadlock in DBMS, the content of the article is of high quality, so the editor will share it with you for reference. I hope you will have a certain understanding of the relevant knowledge after reading this article.

In a database, a deadlock is a situation in which two or more threads are permanently blocked (suspended), waiting indefinitely for each other's conditions to complete, and unlocking data resources. In this case, the task is not completed and is always waiting; therefore, it is considered to be one of the most frightening complications in DBMS. Let's take a look at the conditions under which deadlocks occur and how deadlocks have been prevented.

Conditions under which deadlock occurs

A deadlock may occur if all of the following conditions are met.

1. Mutex condition: at least one resource must not be used by multiple processes at a time.

2. Hold and wait conditions: processes that hold resources can request other resources held by other processes in the system.

3. No preemption condition: you cannot force the acquisition of resources from the process until the use is completed. The resources held by the process can be released only after it has finished using it.

4. Loop wait condition: a situation in which a process is waiting for resources held by a second process and a second process is waiting for a third process. Wait, the last process is waiting for the first process, thus making a loop chain to wait.

How to prevent deadlock

We have learned that if all of the above conditions are true, deadlocks will occur, so blocking one or more of them can prevent deadlocks.

1. Avoid mutual exclusion conditions: all resources must be shareable, which means that multiple processes can obtain resources at a time. But this method is almost impossible to achieve.

2. Avoid holding and waiting conditions: this condition can be avoided if the process gets all the resources it needs before starting. Another way to avoid this condition is not to enforce the rule of requesting resources when the process is held.

3. Preemption of resources: preemption of resources from the process may lead to rollback, so this needs to be avoided to maintain the consistency and stability of the system.

4. Avoid circular wait conditions: this can be avoided if resources are maintained in a hierarchy and the process can save resources in order of increasing priority. This avoids circular waiting. Another way is to enforce a resource for each process rule-a process can request a resource when it releases the resource currently saved by it. This avoids circular waiting.

About what is the deadlock in DBMS to share here, I hope the above content can be of some help to you, can learn more knowledge. If you think the article is good, you can share it for more people to see.

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