What is the concept of deadlock?

Deadlock means that in concurrent computing, two or more processes fall into an infinite waiting state because they are waiting for each other to release resources, causing the system to be unable to continue execution. Deadlock is a situation of resource competition. , where each participant is waiting for other participants to release resources, but due to interdependence between each other, no participant is able to continue execution.

# Operating system for this tutorial: Windows 10 system, Dell G3 computer.

Deadlock means that in concurrent computing, two or more processes (or threads) fall into an infinite waiting state because they are waiting for each other to release resources, causing the system to be unable to continue executing. Simply put, a deadlock is a situation of resource contention in which each participant is waiting for the other participants to release resources, but no participant is able to continue execution due to their interdependence.

Deadlock usually involves the following four necessary conditions:

1. Mutual Exclusion: At least one resource can only be used by one process (or thread) at the same time Occupied, that is, it can only be occupied by one process at a certain time.

2. Request and hold conditions (Hold and Wait): A process still holds the resources it has obtained while waiting for the resources assigned to it.

3. No Preemption condition (No Preemption): Resources that have been allocated to a process cannot be forcibly deprived and can only be released by the process itself.

4. Circular Wait Condition (Circular Wait): There is a process chain, and each process is waiting for the resources occupied by the next process, forming a closed-loop waiting chain.

When these four conditions are met at the same time, a deadlock will occur. In a deadlock state, the system will be unable to proceed unless intervention is taken to break the deadlock.

The occurrence of deadlock may lead to a waste of system resources, performance degradation, and even system crash. Therefore, when designing a concurrent system, it is necessary to avoid deadlocks and prevent and handle deadlocks through reasonable resource allocation and scheduling algorithms.

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