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Table of contents
1.
Introduction
2.
What is Starvation in OS (Operating System)?
3.
What exactly does starvation mean in operating systems?
4.
What Causes Starvation in OS?
5.
Example of Starvation In OS
6.
How to Prevent Starvation in OS?
6.1.
Aging
6.2.
Round Robin Scheduling
6.3.
Resource Reservation
7.
What Is Deadlock?
8.
Difference Between Deadlock And Starvation in OS
9.
How is Starvation in OS different from Deadlock?
10.
Frequently Asked Questions 
10.1.
What are the 2 types of starvation?
10.2.
What is Starvation in an Operating System?
10.3.
Does SJF cause starvation? 
10.4.
What is starvation freedom? 
10.5.
What are the 3 stages of starvation? 
11.
Conclusion
Last Updated: Apr 22, 2024
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Starvation in OS

Author Gunjan Batra
1 upvote
Roadmap to SDE career at Amazon
Speaker
Anubhav Sinha
SDE-2 @
25 Jun, 2024 @ 01:30 PM

Introduction

Starvation is a resource management issue in which a process is unable to obtain necessary resources, such as network bandwidth, for an extended period due to allocation to other processes. 
This problem often occurs in priority-based scheduling systems, where high-priority requests are handled first, causing delays for lower-priority tasks.

Starvation in OS

Let's dive into this topic to understand it better.

What is Starvation in OS (Operating System)?

Starvation in OS is a problem that occurs when low-priority processes are indefinitely blocked from executing due to high-priority processes. This typically happens in a scheduling system, where certain low-priority processes are repeatedly overlooked in favor of high-priority ones. The overlooked processes, thus, "starve", unable to complete their execution.

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What exactly does starvation mean in operating systems?

In the context of operating systems, "starvation" refers to a situation where a process or a resource is unable to make progress or access a particular resource it needs due to the allocation of resources to other processes or tasks. This can lead to unfairness and inefficiency in resource allocation, and it's a problem that can occur in multi-tasking or multi-threaded environments where multiple processes or threads compete for resources.

Starvation can occur in various scenarios, and the most common type is "resource starvation," where a process is unable to obtain a necessary resource, such as CPU time, memory, or I/O resources, for an extended period. This typically occurs because other processes or threads are monopolizing the resource, preventing fair access for others. Resource allocation mechanisms within an operating system, like scheduling algorithms, are responsible for managing and preventing starvation.

What Causes Starvation in OS?

One of the main causes of starvation is an unfair scheduling policy. Some scheduling algorithms, such as the Priority Scheduling algorithm, favor high-priority processes over low-priority ones. If the system is busy with high-priority processes, the low-priority processes might be left waiting indefinitely.

Another cause could be resource allocation issues. If a certain process holds a resource that another process needs to continue execution, and it doesn't release it, the waiting process can starve

Example of Starvation In OS

An example of starvation in an operating system is when a low-priority background task, such as a file backup process, constantly loses access to CPU resources because a high-priority real-time process, like an emergency response system, is given precedence. This can lead to the backup process making very slow progress or being unable to complete its task, which is a form of starvation.

How to Prevent Starvation in OS?

Preventing starvation involves ensuring fair allocation of CPU time and other resources. Various techniques can be used for this purpose:

Aging

Aging is a technique where the priorities of processes are gradually increased the longer they wait. This way, even low-priority processes will eventually have their priority elevated enough to be executed, preventing starvation.

Round Robin Scheduling

Round Robin is a scheduling algorithm where each process gets a small unit of CPU time (time quantum). It cycles through the queue of processes, giving each one its fair share of CPU time, thus preventing any one process from starving.

Resource Reservation

Resource Reservation is a strategy where each process is guaranteed a minimum amount of resources. By ensuring each process receives a certain minimum share, no process goes indefinitely without resources, thus preventing starvation.

Also see, Difference Between Bit and Byte

What Is Deadlock?

Deadlock is a situation in computer science where two or more processes are unable to proceed because each is waiting for the other to release a resource, resulting in a stalemate. In a deadlock scenario, none of the processes can proceed, leading to a system-wide halt. Deadlocks typically occur in concurrent systems where processes compete for shared resources such as memory, CPU time, or I/O devices. Without proper handling mechanisms, deadlocks can cause system instability and hinder overall system performance.

Difference Between Deadlock And Starvation in OS

FeatureDeadlockStarvation
DefinitionDeadlock occurs when processes are unable to proceed because each is waiting for a resource held by another process.Starvation occurs when a process is perpetually denied access to resources it needs to proceed.
CauseCaused by circular dependency on resources among processes.Caused by unfair resource allocation policies or scheduling algorithms.
ResolutionRequires intervention mechanisms like deadlock detection and avoidance.Can be mitigated by fair resource allocation policies or scheduling algorithms.
ImpactResults in a system-wide halt, where none of the processes can proceed.Affects individual processes, leading to reduced performance or responsiveness.
Resource UsageResources involved in a deadlock are effectively wasted.Resources are not wasted but are not utilized efficiently by the starving process.
OccurrenceLess frequent but potentially more severe in its impact.More common in systems with poor resource management or scheduling algorithms.

How is Starvation in OS different from Deadlock?

Starvation and deadlock are both issues related to resource allocation and process synchronization in operating systems, but they are different in several key ways:

Nature of the Problem:

  • Starvation: Starvation is a situation where a process or resource is consistently denied access to essential resources, like CPU time, memory, or I/O, due to resource allocation prioritization. It is a livelock issue, meaning the process is actively trying to access resources but is consistently delayed or hindered by other processes.
  • Deadlock: Deadlock is a situation where multiple processes are each waiting for a resource held by one of the other waiting processes, resulting in a circular waiting pattern. In this case, processes are effectively stuck and unable to proceed.

Cause:

  • Starvation: Starvation is typically caused by resource allocation policies that favor certain processes over others, leading to unfair resource distribution.
  • Deadlock: Deadlock arises when processes are waiting for resources that are held by other processes, creating a situation where none of them can progress.

Resource Access:

  • Starvation: In cases of starvation, processes continue to actively access and request resources, but they are repeatedly delayed or preempted by other, higher-priority processes.
  • Deadlock: In a deadlock, processes are effectively frozen and unable to proceed, as they are all waiting for resources held by one another.

Resolution:

  • Starvation: To address starvation, resource allocation policies or scheduling algorithms can be adjusted to ensure fair resource distribution among competing processes.
  • Deadlock: Deadlocks are typically resolved using methods like resource preemption (forcibly taking resources from a waiting process) or by releasing resources and restarting affected processes.

In summary, starvation involves processes being consistently delayed or denied access to resources, while deadlock is a situation where multiple processes are mutually waiting for resources, rendering them all unproductive. Both issues can negatively impact system performance, and addressing them requires different strategies and solutions.

Frequently Asked Questions 

What are the 2 types of starvation?

  1. Resource Starvation: Occurs when processes are denied access to essential resources like CPU time or memory.
  2. Time Starvation: When a process waits indefinitely for a turn or event to occur.

What is Starvation in an Operating System?

Starvation is a scenario where a process is perpetually denied necessary resources, causing it to be unable to complete its execution.

Does SJF cause starvation? 

The shortest Job First (SJF) scheduling algorithm can cause starvation for longer processes if shorter processes continuously arrive, as longer processes may never get a chance to execute, leading to delayed or indefinitely postponed execution.

What is starvation freedom? 

Starvation freedom refers to a system's ability to guarantee that no process will be denied access to resources indefinitely, ensuring that all processes eventually receive the resources they need to proceed with execution.

What are the 3 stages of starvation? 

The three stages of starvation are initiation, maintenance, and recovery. Initiation occurs when a process is denied resources, maintenance involves the continued denial of resources, and recovery is the stage where resources are finally allocated to the starved process.

Conclusion

Understanding starvation in Operating Systems is key to managing system resources efficiently. It's a problem that arises due to unfair allocation of resources and can cause certain processes to wait indefinitely for their turn to execute. Several techniques such as Aging, Round Robin scheduling, and Resource Reservation can be used to prevent starvation. Being aware of these can help in designing an OS that provides fair resource distribution, ensuring smooth and efficient execution of all processes.

Recommended Readings:

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