To prevent a deadlock from occurring, it is possible to break its 4 conditions, but it is not practi

Deadlock. It is the source eggplant process that competes for mutually exclusive resources, resulting in at least two programs not working properly.

Deadlocks create four conditions: mutually exclusive resources, request and hold, loop waiting, and inalienable dispersion.

Deadlock prevention: Destroying one or more of the condition's Mutually exclusive resource --- spooling techniques Requesting and holding--- allocating resources statically or allocating resources at once Loop waiting --- orderly allocation Inalienable --- deprivable.

Deadlock Avoidance: Banker's Algorithm.

Prevent the system from entering an unsafe state.

1.Deadlock prevention: Deadlocks are prevented by setting some restrictions to destroy one or more of the conditions necessary to produce a deadlock.

2.Deadlock avoidance: In the process of resource allocation, use a method to avoid the system from entering an unsafe state, so as to avoid deadlocks.

3.Deadlock detection: Deadlocks are allowed, but after being detected by the system, some measures are taken to remove the deadlocks.

4.Deadlock release: When a deadlock is detected, appropriate measures are taken to free the process from the deadlock state.

Deadlock. of fourNecessaryWhat can't be broken is the mutually exclusive use of resources.

How it works: When every process in a group of processes is waiting for an event to occur, and only other processes in the group can trigger the event, the group of processes is said to have a deadlock.

Essential reasons: limited system resources; The sequence of progress is not reasonable.

There are 4 necessary conditions for deadlocks to occur:

1. Mutual exclusivity: A certain resource is only allowed to be accessed by one process at a time, that is, once the resource is assigned to a process, other processes can no longer access it until the end of the process access.

2. Possession and waiting: A process itself occupies one or more resources, and at the same time, there are resources that are not satisfied, and are waiting for other processes to release the resources.

3. Don't preemptive: Someone else already has a certain resource, and you can't grab someone else's resource just because you also need it.

When the above four conditions are met, it will inevitably cause deadlocks, and the process of entering the forest and closing rocks where deadlocks occur cannot be carried out, and the resources they hold cannot be released. This results in CPU throughput.

Decline. Therefore, deadlocks will waste system resources and affect the performance of the computer.

What is a deadlock? What are the causes and necessary conditions for deadlocks to occur are as follows:

1) A set of processes, each process is indefinitely waiting for resources occupied by another process in the group of processes, so that it can never get resources, this phenomenon is called process deadlock, this group of processes is called deadlock process.

2) The root cause: limited resources and improper operation.

3) Necessary conditions: mutually exclusive conditions, non-preemptive judgment seepage parts, possession and application conditions, cyclic waiting conditions.

The canonical definition of a deadlock is that every process in a collection is waiting for an event that can only be raised by other processes in the collection, then the group of processes is deadlocked.

Deadlock Impulsion: A situation in which two or more processes in the executor are permanently blocked (waiting), and each process is waiting for resources that are occupied and clogged by other processes. For example, if process A locks record 1 and waits for record 2, and process B locks record 2 and waits for record 1, then both processes have a deadlock.

In the computer spine system, if the system's resource allocation strategy is not appropriate, it is more common that the program written by the programmer has errors, etc., which will lead to the phenomenon of deadlock in the process due to improper competition for resources.

In two or more tasks, if each task locks a resource that the other tasks are trying to lock, the tasks are permanently blocked, resulting in a deadlock. For example: Transaction A acquires a shared lock on line 1. Transaction B acquires a shared lock on line 2.

The exclusive lock is blocked before waiting for transaction B to complete and release the shared lock it holds on line 2.

The exclusive lock is blocked before waiting for transaction A to complete and release the shared lock it holds on line 1.

Answer]: C produces four necessary conditions for the collapse of deadlocks:

Mutex: A resource can only be used by one process at a time.

Request and Hold Conditions: When a process is blocked by a request for a resource, it keeps on with the resources it has obtained.

Non-deprivation conditions: The process has acquired the resources of the infiltration hall and cannot be forcibly deprived until they are exhausted.

Cyclic Wait Condition: Several processes form a cyclic wait-resource relationship that is head-to-end.

These four conditions are necessary for deadlocks, and as long as a deadlock occurs in the system, these conditions must be true, and as long as one of the above conditions is not met, a deadlock will not occur.

So in the stem, the condition of non-deprivation needs to be broken, so the answer is c.

The 4 necessary conditions for deadlocks do not include the following ().

a.Mutually exclusive conditions.

b.Do not deprive the clan of the loss condition.

c.Request to maintain the condition of the God of Annihilation.

d.Link conditions.

Correct answer: d

The four necessary conditions for deadlocking are as follows:

1. Mutually exclusive use, a resource can only be used by one process at a time, and multiple processes are not allowed to use a resource at the same time.

2. No forcible occupation, resource applicants cannot forcibly seize resources from the resource occupier, resources can only be voluntarily released by the occupier and obtained by the applicant.

3. Request and retention, a process in the application of new resources while maintaining the possession of the original resources, other applicants can not obtain.

4. Cyclic waiting, there is a process waiting queue, in which the last executed program waits for the previous executed program to be completed, forming a process waiting loop.