2. How does Java handle memory management? Explain the role of the Garbage Collector and different types of garbage collection algorithms.
Java handles memory management primarily through automatic memory management using the Java Virtual Machine (JVM). This involves allocating and deallocating memory for objects in a way that is mostly transparent to the developer.
Role of Garbage Collector (GC):
The Garbage Collector in Java automatically identifies and removes objects that are no longer in use, freeing up memory and preventing memory leaks. It manages the heap memory and eliminates the need for explicit memory deallocation by developers.
Key Responsibilities of GC:
1. Identifying unreachable objects: Objects that are no longer referenced are eligible for garbage collection.
2. Reclaiming memory: Releasing memory occupied by unreachable objects.
3. Compacting memory: After reclaiming, it may compact the heap to reduce fragmentation.
Types of Garbage Collection Algorithms:
1. Serial GC:
o Uses a single thread.
o Suitable for small applications with single-threaded environments.
2. Parallel GC (Throughput Collector):
o Uses multiple threads to perform minor and major garbage collection.
o Best for applications with medium to large heaps.
3. Concurrent Mark-Sweep (CMS) GC:
o Focuses on low-latency requirements.
o Performs most of its work concurrently with the application.
4. G1 (Garbage-First) GC:
o Divides the heap into regions and prioritizes garbage collection in regions with the most garbage.
o Suitable for large heaps and applications requiring predictable pause times.
5. Z Garbage Collector (ZGC):
o Low-latency collector designed for very large heaps (up to terabytes).
o Operates mostly concurrently.
6. Shenandoah GC:
o Another low-pause-time collector with concurrent compaction.
The Java Garbage Collector automates memory management by reclaiming unused objects in heap memory. Algorithms like Serial, Parallel, CMS, G1, ZGC, and Shenandoah cater to different application requirements, balancing throughput, latency, and scalability.
Discussion 0