Garbage Collector Functioning Explained In Depth | How Garbage Collector works in Java

Hey everyone, in this video we discussed the working of Garbage Collector in Java. The question comes as to why there is a need to even have a garbage collector in Java when in c/c++ we don't have it. Watch the video till the very end, All the questions have been answered.

In C/C++, a programmer is responsible for both the creation and destruction of objects. Usually, programmer neglects the destruction of useless objects. Due to this negligence, at a certain point, sufficient memory may not be available to create new objects, and the entire program will terminate abnormally, causing OutOfMemoryErrors.

But in Java, the programmer need not care for all those objects which are no longer in use. Garbage collector destroys these objects. The main objective of the Garbage Collector is to free heap memory by destroying unreachable objects. The garbage collector is the best example of the Daemon thread as it is always running in the background.

In the realm of Java programming, memory management is a critical aspect, and the Garbage Collector (GC) plays a pivotal role in ensuring efficient memory usage. The Java Garbage Collector is responsible for identifying and reclaiming memory occupied by objects that are no longer in use. Let's dive into the inner workings of the Java Garbage Collector to unravel its complexities.

Understanding the Basics:
Java employs automatic memory management, meaning developers don't need to explicitly allocate or deallocate memory. Instead, the Java Virtual Machine (JVM) includes a Garbage Collector that automatically handles memory operations.

Memory Management in Java:
When objects are created in Java, they are allocated memory on the heap. The heap is the region of memory reserved for dynamic memory allocation. Over time, as objects are created and references to them are established, some objects become unreachable and are candidates for removal.

Mark and Sweep Algorithm:
The Java Garbage Collector primarily uses the Mark and Sweep algorithm. Here's a step-by-step breakdown of how it works:

Marking Phase:

The Garbage Collector starts by marking all live objects. It begins from the root of the object graph (usually the main method or global variables) and traverses all reachable objects, marking them as "live."
Sweeping Phase:

In this phase, the Garbage Collector identifies and sweeps away the memory occupied by objects not marked as "live" in the previous step. This memory is considered garbage and is now available for new object allocations.
Compaction (Optional):

Some Garbage Collectors, like the G1 Garbage Collector, include an optional compaction phase. This phase reclaims fragmented memory by compacting the live objects, ensuring a more contiguous and efficient memory layout.
Generational Garbage Collection:
Java's Garbage Collector also implements a generational garbage collection strategy. It divides the heap into two main areas:

Young Generation:

Newly created objects are initially allocated in the Young Generation. The assumption is that most objects have a short lifespan. The Young Generation is further divided into three spaces: Eden, and two Survivor spaces (S0 and S1).
Old Generation:

Objects that survive multiple garbage collection cycles in the Young Generation are eventually promoted to the Old Generation. This area contains long-lived objects.
Types of Garbage Collectors in Java:
Java offers several types of Garbage Collectors to cater to different application needs:

Serial Garbage Collector:

Suitable for single-threaded applications or applications with small to medium-sized datasets.
Parallel Garbage Collector:

Designed for multi-threaded applications, the Parallel Garbage Collector uses multiple threads to perform garbage collection in the Young Generation.
Concurrent Mark-Sweep (CMS) Garbage Collector:

Minimizes application pause times by performing most of the garbage collection work concurrently with the application threads.
G1 Garbage Collector:

The Garbage-First Garbage Collector is designed for large heaps and aims to provide more predictable pause times.
Tuning and Monitoring:
Java developers often need to fine-tune garbage collection settings based on the application's requirements. Monitoring tools like Java Mission Control and VisualVM provide insights into memory usage, garbage collection activity, and overall application performance.

Conclusion:
Understanding how the Java Garbage Collector works is essential for Java developers aiming to build efficient and responsive applications. The automatic memory management provided by the Garbage Collector simplifies memory-related tasks, allowing developers to focus more on application logic. As you delve deeper into Java development, exploring the nuances of garbage collection will empower you to optimize memory usage and enhance the performance of your Java applications.

Happy coding! 🚀🔍

[MrPusio]

3:25 - primitive types are stored in stack memory. The only way to store number in a heap memory is to use Wrapper class like Integer using keyword New.

[ashwanidasari]

Nitish u r so cute 😍
Ur teaching also good

[rohitmalhotra]

Nice one, Can you also make a video explaining how Generic works? or How Lambda Expression work?

[munawarabbas]

int is not a object data type.i like your effort but totally wrong examples shown here.Please update video or remove it.