Starvation in Operating Systems

Have you ever been in a situation where you’re waiting in line for something, but people keep cutting in front of you, and you never seem to get your turn? This scenario is similar to what happens in an operating system when a process experiences starvation. Let’s dive into this concept and break it down in simple terms.

What is Starvation?

In the world of operating systems, starvation occurs when a process is perpetually denied the resources it needs to execute for an extended period. It’s akin to a hungry person at a buffet who can’t reach the food because others keep pushing in front of them. This problem is common in concurrent computing, where multiple processes run simultaneously and compete for limited resources.

Why Does Starvation Happen?

Starvation typically results from poor resource allocation strategies, errors in scheduling, or mutual exclusion algorithms. Here are a few common scenarios:

1. Priority Issues: If an operating system always favors high-priority processes, lower-priority ones might never get a chance to run. For example, a high-priority process might block and never yield, causing a low-priority process to experience starvation.
2. Resource Hogging: Some processes might hold onto resources for too long, preventing others from accessing them. This can lead to scenarios where essential processes are unable to perform their tasks.
3. Inefficient Scheduling: A flawed scheduling algorithm might consistently overlook certain processes. For instance, if a multitasking system switches between the first two tasks and never allows a third task to run, that task is starved of CPU time.
4. Resource Leaks: Resource leaks can cause starvation by preventing processes from accessing the necessary resources to proceed.
5. Denial-of-Service Attacks: Starvation can also be intentionally caused via denial-of-service attacks, such as a fork bomb, which depletes system resources and prevents legitimate processes from executing.

Preventing Starvation

Operating systems use various techniques to prevent starvation:

1. Aging: This technique gradually increases the priority of processes that have been waiting for a long time, ensuring that all processes eventually get the resources they need.
2. Fair Scheduling: Algorithms are designed to ensure all processes get a fair share of CPU time and resources. Modern scheduling algorithms often include mechanisms to guarantee minimum resource allocation to prevent starvation.
3. Resource Limits: Setting maximum time limits for how long a process can hold onto resources prevents resource hogging and ensures equitable distribution.
4. Priority Adjustments: Dynamically adjusting process priorities based on their waiting time and resource needs helps ensure that lower-priority processes are not indefinitely delayed.
5. Starvation-Free Algorithms: A starvation-free or lockout-free algorithm guarantees that any process is bypassed at most a finite number of times before accessing the shared resource, ensuring fairness in resource allocation.