Understanding Evictors in Memory Management

Evictors are a type of memory management mechanism used in computer systems to reclaim memory that is no longer being used by the program.

When a program requests memory from the operating system, the operating system does not immediately grant the request. Instead, it allocates the memory and marks it as "free" in a data structure called a "free list". The program can then use the allocated memory until it is no longer needed, at which point the operating system can reclaim the memory by removing it from the free list and adding it back to the pool of available memory.

Evictors are used to remove memory from the free list when it is no longer being used by the program. There are two types of evictors:

1. LRU (Least Recently Used) evictor: This type of evictor removes the memory block that has not been accessed for the longest time.
2. FIFO (First-In-First-Out) evictor: This type of evictor removes the memory block that was allocated first.

The purpose of using evictors is to prevent memory leaks, which can occur when a program allocates memory but does not release it when it is no longer needed. By periodically removing unused memory from the free list, the operating system can ensure that memory is always available for new requests and prevent the system from running out of memory.