Operating System Tutorial

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Operating Systems

Linux Operating System Unix Operating System Ubuntu Operating System Chrome Operating Systems Fedora Operating System MAC Operating System MS Windows Operating System Solaris Operating System Cooperative Operating System CorelDRAW Operating System CentOS FreeBSD Operating Systems Batch Operating System MS-DOS Operating System Commercial Mobile Operating Systems


Difference Between Multi-programming and Multitasking Difference between C-LOOK and C-SCAN Difference between Rotational Latency and Disk Assess Time Trap vs Interrupt Difference between C-SCAN and SSTF Difference between SCAN and FCFS Difference between Seek Time and Disk Access Time Difference between SSTF and LOOK Difference between Process and Program in the Operating System Difference between Protection and Security in Operating System

How To

How to implement Monitors using Semaphores How to Install a Different Operating System on a PC


What is Kernel and Types of Kernel What is DOS Operating System What is Thread and Types of Thread What is Process Scheduler and Process Queue What is Context Switching What is CPU Scheduling What is Producer-Consumer Problem What is Semaphore in Operating System Monitors in Operating System What is Deadlock What is Paging and Segmentation What is Demand Paging What is Virtual Memory What is a Long term Scheduler What is Page Replacement in Operating System What is BSR Mode What is Convoy Effect What is Job Sequencing in Operating System Why is it critical for the Scheduler to distinguish between I/O-bound and CPU-bound programs Why is there a Need for an Operating System


Process Management Process State Scheduling Algorithm FCFS (First-come-First-Serve) Scheduling SJF (Shortest Job First) Scheduling Round-Robin CPU Scheduling Priority Based Scheduling HRRN (Highest Response Ratio Next) Scheduling Process Synchronization Lock Variable Mechanism TSL Mechanism Turn Variable Mechanism Interested Variable Mechanism Deadlock Avoidance Strategies for Handling Deadlock Deadlock Prevention Deadlock Detection and Recovery Resource Allocation Graph Banker’s Algorithm in Operating System Fixed Partitioning and Dynamic Partitioning Partitioning Algorithms Disk Scheduling Algorithms FCFS and SSTF Disk Scheduling Algorithm SCAN and C-SCAN Disk Scheduling Algorithm Look and C-Look Disk Scheduling Algorithm File in Operating System File Access Methods in Operating System File Allocation Method Directory Structure in Operating System N-Step-SCAN Disk Scheduling Feedback Queue in Operating System Contiguous Memory Allocation in Operating System Real-time Operating System Starvation in Operating System Thrashing in Operating System 5 Goals of Operating System Advantages of Operating System Advantages of UNIX Operating System Bit Vector in Operating System Booting Process in Operating System Can a Computer Run Without the Operating System Dining Philosophers Problem in Operating System Free Space Management in Operating System Inter Process Communication in Operating System Swapping in Operating System Memory Management in Operating System Multiprogramming Operating System Multitasking Operating Systems Multi-user Operating Systems Non-Contiguous Memory Allocation in Operating System Page Table in Operating System Process Scheduling in Operating System Segmentation in Operating System Simple Structure in Operating System Single-User Operating System Two Phase Locking Protocol Advantages and Disadvantages of Operating System Arithmetic operations in binary number system Assemblers in the operating system Bakery Algorithm in Operating System Benefits of Ubuntu Operating System CPU Scheduling Criteria in Operating System Critical Section in Operating System Device Management in Operating System Linux Scheduler in Operating System Long Term Scheduler in Operating System Mutex in Operating System Operating System Failure Peterson's Solution in Operating System Privileged and Non-Privileged Instructions in Operating System Swapping in Operating System Types of Operating System Zombie and Orphan Process in Operating System 62-bit operating system Advantages and Disadvantages of Batch Operating System Boot Block and Bad Block in Operating System Contiguous and Non - Contiguous Memory Allocation in Operating System Control and Distribution Systems in Operations Management Control Program in Operating System Convergent Technologies in Operating System Convoy Effect in Operating System Copy Operating Systems to SSD Core Components of Operating System Core of UNIX Operating System Correct Value to return to the Operating System Corrupted Operating System Cos is Smart Card Operating System Cosmos Operating Systems Examples Generation of Operating System Hardware Solution in Operating System Process Control Block in Operating System Function of Kernel in Operating System Operating System Layers History of Debian Operating Systems Branches and Architecture of Debian Operating Systems Features and Packages of Debian Operating Systems Installation of Operating System on a New PC Organizational Structure and Development in Debian Operating Systems User Interface in Operating System Types Of Memory in OS Operating System in Nokia Multilevel Paging in OS Memory Mapping Techniques in OS Memory Layout of a Process in Operating System Hardware Protection in Operating System Functions of File Management in Operating System Core of Linux Operating System Cache Replacement Policy in Operating System Cache Line and Cache Size in Operating System What is Memory Mapping? Difference Between Network Operating System And Distributed Operating System What is the difference between a Hard link and a Soft Link? Principles of Preemptive Scheduling Process Scheduling Algorithms What is NOS? What is the Interrupt I/O Process? What is Time Sharing OS What is process termination? What is Time-Sharing Operating System What is Batch File File system manipulation What is Message-passing Technique in OS Logical Clock in Distributed System

What is Deadlock in OS?

Deadlock in Operating System

In an Operating System, a process uses various resources, and the resources are used in the following manner:

  1. Request the Resource
  2. Use the Resource
  3. Release the Resource

In the Operating System, Deadlock is a condition where two or more than two processes need to use some resources to finish its execution and that resources are held by some another process.

In other words, Deadlock is defined as a situation in which the processes are in the blocked state. As each process is holding a resource and waiting for another resource, which is held by some other process.

Now we take an example to understand the concept of Deadlock. Suppose we have three processes P1, P2, and P3, and we have three resources R1, R2, and R3. The resource R1 is allocated to the Process P1, resource R2 is allocated to the Process P2, and the resource R3 is allocated to the Process P3.

After some time, the process P1 request for resource R2, which is allocated to Process P2. So, in this situation, P1 stops its execution because, without R2 resources, P1 cannot finish its execution. The process P2 wants to use the resource R3, but the P3 process is held with R3. So in this way, P2 also stops its execution. Now, the P3 process also requests for R1 resources, which is held by the process P1, so P3 halts its execution.

In this condition, a cyclic situation will make among the processes, and no process will progress, and all the processes will be in the waiting state. So, in this situation, the computer will not be responsive, and all the processes will be blocked.

Deadlock in Operating System

Difference between Deadlock and Starvation

            Deadlock             Starvation
In a Deadlock, processes wait for each other to release its resources, and no process gets executed. In Starvation, the processes which are having high priority get executed, and the processes having low priority get blocked.
The conditions which are required for Deadlock are Mutual Exclusion, Hold and Wait, No Preemption, and Circular Wait. In Starvation, we assign priorities to the processes.
In a Deadlock, resources are blocked by the processes. In Starvation, the processes which are having high priority utilize resources continuously.
Deadlock is also called Circular wait Starvation is also called lived lock
With the help of necessary conditions, a deadlock can be prevented. With the help of aging, Starvation can be prevented.
In a deadlock, for ending, external intervention is needed. In Starvation, for ending, no external intervention is needed.

Advantages of Deadlock

The advantages of Deadlock are:

  1. Deadlock is suitable for those processes that perform a single burst of activity.
  2. In Deadlock, Preemption is not required.
  3. Deadlock is one of the efficient methods which we use for those resources where the state of resources can be saved and restored.
  4. Deadlock is feasible to enforce through compile-time checks.
  5. In Deadlock, run-time computation is not required because we can solve the problem in system design.

 Disadvantages of Deadlock

  1. It is a must to know the future resources required for the process.
  2. Essential preemption losses.
  3. It preempts the resources more than the requirement.
  4. Deadlock takes more time for process initiation.

How to Avoid Deadlock

We can avoid Deadlock by preventing four conditions:

  1. Mutual Exclusion
  2. Hold and Wait
  3. No Preemption
  4. Circular Wait
  1. Mutual Exclusion: - Mutual Exclusion means at the same time, more than two processes can use the same resources, and resources can be shared in mutual exclusion way.
  2. Hold and Wait: - Hold and Wait means we must take care that one process is not holding one or more resources and also concurrently waiting for other resources.
  3. No Preemption: - With the help of preemption of the process's resource allocations, we can also avoid Deadlock.
  4. Circular Wait: -We can also avoid Deadlock by preventing the number of processes from the circular wait. We can prevent circular wait by numbering the resources and the process requests for resources only in the ascending or descending order.

Handling Deadlock

The points which we discussed above are useful for deadlock prevention. But we also consider some points for handling deadlock if Deadlock has occurred.

We can use some essential strategies to remove Deadlock if it has occurred:

  1. Preemption
  2. Rollback
  3. Kill one or more Processes

Preemption: - By taking the resource back from the process and provide that resource to other process is helpful to solve the problem of Deadlock, but sometimes there may be a possibility of problems.

Rollback: - In some cases, where there may be a chance of Deadlock then the system prepares a record of all process states, and if a deadlock has occurred then we can easily roll back to the last checkpoint and then restart, but we allocate resources differently so that the Deadlock can never occur again. So, with the help of rollback, we can handle Deadlock.

Kill one or more processes: - Kill one or more processes is one of the easiest strategies for deadlock handling.

What is Livelock?

Livelock is a type of Deadlock. Livelock is just like a deadlock. Livelock means a condition where two or more processes switch their state frequently for the alteration in the processes without performing any beneficial task. It is the same as Deadlock, where progress is not made. But, in livelock, the process is not blocked or waiting.