Deadlock vs. Starvation

Attribute	Deadlock	Starvation
Definition	A situation where two or more processes are unable to proceed because each is waiting for the other to release a resource.	A situation where a process is unable to proceed because it is not being granted the required resources.
Cause	Resource contention and circular wait.	Resource allocation policies and priority inversion.
Resolution	Prevention, avoidance, detection, and recovery.	Priority-based scheduling, resource allocation strategies, and fairness policies.
Effect	System deadlock leads to a complete halt in progress.	Starvation affects the performance and responsiveness of the system.
Resource Ownership	Processes hold resources while waiting for others.	Processes may not be granted resources they need.
Resource Release	Deadlocked processes cannot release resources.	Starved processes may release resources when they are done.
Process Interaction	Deadlocked processes are independent and unaware of each other.	Starved processes may interact with other processes.
Occurrence	Deadlock can occur in any system with shared resources.	Starvation can occur in systems with resource allocation policies.

Introduction

Deadlock and starvation are two common issues that can occur in concurrent systems, particularly in operating systems and distributed computing environments. While both problems can disrupt the normal execution of processes, they have distinct attributes and implications. In this article, we will explore the characteristics of deadlock and starvation, highlighting their differences and providing insights into their causes, effects, and potential solutions.

Deadlock

Deadlock refers to a situation where two or more processes are unable to proceed because each is waiting for a resource held by another process in the set. It creates a state of impasse, where none of the processes can continue execution, leading to a system freeze. Deadlocks typically occur due to the presence of four necessary conditions: mutual exclusion, hold and wait, no preemption, and circular wait.

Mutual exclusion means that only one process can access a resource at a time. Hold and wait implies that a process holding a resource can request additional resources while still holding the current ones. No preemption means that resources cannot be forcibly taken away from a process. Circular wait refers to a circular chain of processes, where each process is waiting for a resource held by the next process in the chain.

When a deadlock occurs, the system may require intervention to resolve the impasse. Common techniques for deadlock handling include deadlock detection, avoidance, prevention, and recovery. Deadlock detection involves periodically checking the system's resource allocation state to identify potential deadlocks. Deadlock avoidance aims to dynamically allocate resources in a way that avoids the possibility of deadlock. Deadlock prevention focuses on eliminating one or more of the necessary conditions for deadlock occurrence. Deadlock recovery involves terminating one or more processes to break the deadlock and release the resources.

Starvation

Starvation, on the other hand, refers to a situation where a process is unable to proceed or make progress due to the unfair or insufficient allocation of resources. Unlike deadlock, starvation does not involve a complete system freeze but rather affects the execution of specific processes. It occurs when a process is perpetually denied access to a resource it requires, leading to a prolonged delay or even indefinite postponement of its execution.

Starvation can be caused by various factors, such as resource scheduling algorithms that prioritize certain processes over others, resource leaks, or inefficient resource allocation policies. When a process is starved, it remains in a waiting state indefinitely, unable to complete its execution or fulfill its intended purpose. This can lead to reduced system performance, decreased throughput, and unfairness in resource allocation.

To mitigate starvation, various techniques can be employed. One approach is to use fair scheduling algorithms that ensure each process receives a fair share of resources over time. Another technique involves implementing priority-based resource allocation, where processes with higher priority are given precedence in resource allocation decisions. Additionally, resource monitoring and management can help identify and resolve resource leaks or inefficient allocation policies that contribute to starvation.

Comparison

While deadlock and starvation both involve issues related to resource allocation and process execution, they differ in several key aspects. Deadlock results in a complete system freeze, where no process can proceed, while starvation affects specific processes, allowing others to continue execution. Deadlock is caused by the presence of four necessary conditions, whereas starvation can be caused by unfair scheduling, resource leaks, or inefficient allocation policies.

Deadlock requires intervention to resolve the impasse, often through techniques like deadlock detection, avoidance, prevention, or recovery. In contrast, starvation can be mitigated by employing fair scheduling algorithms, priority-based resource allocation, or addressing resource leaks and inefficient allocation policies.

Another distinction lies in the impact on system performance. Deadlock can significantly impact system performance as it freezes the entire system, leading to a complete halt in execution. Starvation, on the other hand, affects specific processes, potentially reducing their performance and throughput, but allowing other processes to continue execution.

Furthermore, the causes of deadlock and starvation differ. Deadlock is primarily caused by the presence of four necessary conditions, while starvation can be caused by unfair scheduling, resource leaks, or inefficient allocation policies. Deadlock is a more complex issue to resolve, often requiring sophisticated techniques and algorithms, whereas starvation can be addressed through relatively simpler strategies.

Conclusion

Deadlock and starvation are two distinct problems that can occur in concurrent systems. Deadlock results in a complete system freeze, while starvation affects specific processes. Deadlock is caused by the presence of four necessary conditions, while starvation can be caused by unfair scheduling, resource leaks, or inefficient allocation policies. Deadlock requires intervention through techniques like detection, avoidance, prevention, or recovery, while starvation can be mitigated by employing fair scheduling algorithms, priority-based resource allocation, or addressing resource leaks and inefficient allocation policies. Understanding the attributes and differences between deadlock and starvation is crucial for designing robust concurrent systems and ensuring efficient resource utilization.