HomeBlogWeb DevelopmentWhat is Deadlock in Operating System (OS)?
It is well-known that every process that is taking place on a system needs the assistance of some resource to get executed. The resource could be in the form of the system’s CPU or some plugged-in device such as the standard input or output device. And as soon as the process ends, the in-use resource is duly released. But when multiple processes start running simultaneously on a system, chances are that each of these processes has to compete for a resource. This competition gets culminated in what tech experts have termed the deadlock in OS.
In this blog, we will analyze in detail what deadlock is in OS, get a clear picture with a deadlock example in OS, methods of dealing with it, and much more. So, hang tight and read till the end. Later, if you wish to learn more about deadlocks, you can do so with our lucrative Full-Stack Developer Bootcamp online.
When more than one process taking place in a system is prevented from getting executed, it is called a deadlock. It happens when a resource is being held up or occupied at the moment because some other processes are running in the background. A deadlock in OS makes it circle the drain since no process is executed.
Let’s understand what deadlock is in the operating system better with this example. Let’s assume that Process 1 and Process 2 are two processes. In the same vein, Resource 1 and Resource 2 are two resources. Supposedly,
Source: Includehelp.com
Subsequently, neither Process 1 nor Process 2 gets executed because the resources needed by them are held up. So, this was a deadlock example resulting in a potential deadlock in the operating system.
It isn’t necessary that a deadlock will happen whenever more than one process, along with more than one resource, is involved. This is because a deadlock is earmarked by four conditions that are to be fulfilled anyhow. These include
Mutually exclusive means that for every process, there is a designated resource that cannot be shared. Henceforth, no two processes can ask for the same resource.
As the name suggests, this deadlock condition in OS requires a process to wait for an occupied resource. This condition cannot be truer. Deadlock example
Only one process can be scheduled at a point in time. So, it is said that no two processes can be executed simultaneously. This implies that only when a process is completed, then only the allocated or occupied resource will be duly released.
Every set of processes waits in a cyclic manner. This keeps them waiting forever, and they never get executed. As a result, deadlocks are called “circular wait” since they get a process stuck in a circular fashion. Every set of processes waits in a cyclic manner. This keeps them waiting forever, and they never get executed. As a result, deadlocks are also called “circular wait” since they get a process stuck in a circular fashion.
So, these were the four conditions of deadlock.
Are you brainstorming about the ways of handling a deadlock in an operating system? Well, it’s time to address your significant concern about handling deadlocks. These include
This method involves identifying the situation of deadlock and following some ways to recover your system from a deadlock. A user can simply abort all the processes that can lead to further potential deadlocks. It is recommended to abort one process at a time rather than ending all the processes simultaneously. Keep aborting the processes till the system returns back to normalcy from the situation of deadlock. Another way out could be of freeing the resources from allocation until the deadlock perishes. This is called “resource preemption”.
As the name goes, if a user prevents any one of the four conditions for a deadlock from taking place, a deadlock will be prevented.
Whenever a process asks for a resource to be allocated, an algorithm is exercised to examine whether this resource allocation is safe for the system or not. If it isn’t safe, then the request is denied. This very algorithm is known as the “deadlock avoidance” method.
UNIX, Windows, and some other operating systems often are oblivious to deadlocks and ignore the situation of a deadlock, whenever it arises. This approach is termed the “Ostrich algorithm”. So, whenever a deadlock occurs, you can simply reboot the PC, and the deadlock will get resolved in no time.
Some users often confuse deadlocks for starvation in OS. However, the two are as different as day and night. Very commonly asked questions “What is starvation in OS” and “what is a deadlock in ” are also answered below. The table below lucidly traces the difference between starvation and deadlock:
| Basis | Starvation | Deadlock |
|---|---|---|
| Definition | It is a process wherein resource-allocation is never done to low-priority resources and subsequently, they are never executed. | It is a situation where more than one process taking place in a system is prevented from getting executed because no resource is allocated to it. |
| Resource allocation | Here, resources are allocated to high-priority processes only. | Resource allocation is not done. |
| Ways to handle | A way to handle starvation is via aging. | By avoiding any of the four necessary conditions for deadlock. |
| Execution | Because of resource allocation, only high-priority resources are executed. | No process ever gets executed. |
| Other names | Starvation in OS is also termed as “lived lock”. | Also termed as “circular wait”. |
Since we are well-versed with what is a deadlock in OS now, let’s get through the following advantages of it:
While the pros of the deadlock method exist, so do the cons:
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Summing it up,
That’s all about the deadlock happening in an operating system. For more such insightful information, stay tuned to our page. Get enrolled in KnowledgeHut’s Full-stack Developer Bootcamp online and learn loads on many such intuitive concepts.
A number of reasons are attributed to causing a deadlock. However, the top cause is the fulfillment of four conditions including the circular set, hold and wait, no preemption, and most importantly, the processes being mutually exclusive.
These include deadlock detection and recovery, deadlock ignorance, deadlock prevention, and lastly, deadlock avoidance. These are also the methods for handling deadlock in operating system.
A Structured Query Language deadlock or SQL deadlock is a situation wherein a resource requested by more than one process is blocked.
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