Deadlock Fundamentals

Deadlock is a situation in operating systems where two or more processes are unable to proceed because each is waiting for a resource that is held by another process in the set. This results in a permanent blocking of the processes involved. Deadlock occurs when four necessary conditions hold simultaneously: mutual exclusion (resources cannot be shared, only one process can use a resource at a time), hold and wait (processes hold resources while waiting for additional resources), no preemption (resources cannot be forcibly taken from processes), and circular wait (a circular chain of processes exists where each process waits for a resource held by the next process in the chain). Deadlocks can involve various types of resources including hardware devices, memory pages, files, database records, and other system resources. Systems handle deadlocks through prevention (designing the system to avoid one of the four conditions), avoidance (dynamically checking if resource allocation might lead to deadlock), detection (periodically checking for deadlock existence), and recovery (breaking deadlocks when they occur). Understanding deadlock fundamentals is crucial for system designers and developers to create robust systems that either avoid deadlocks entirely or can recover from them efficiently, ensuring system reliability and availability.