Garbage collection is an automatic memory management mechanism in Java. It helps to reclaim memory occupied by objects that are no longer being used by the program. Garbage collection in Java is an important aspect of Java programing because it allows developers to focus on the business logic of their code rather than having to manually manage the memory.
In Java, the garbage collector is responsible for allocating memory for new objects. And deallocating memory for objects that are no longer needed. It does this by periodically traversing the object graph. That is starting from the roots (e.g., local variables, method parameters, etc.), and marking all reachable objects as live. Any objects that are not marked as live are considered garbage and are eligible for collection.
There are several different garbage collectors available in Java, each with its own set of characteristics and trade-offs. The choice of the garbage collector in Java can have a significant impact on the performance of an application. So it is important to choose the right one for our needs.
Commonly used garbage collectors in Java
The most commonly used garbage collectors in Java are:
- Serial garbage collector
- This is the simplest and least resource-intensive garbage collector.
- It is suitable for small and medium-sized applications that do not have high memory requirements.
- Parallel garbage collector
- This is a multi-threaded garbage collector that is designed for applications with high memory requirements.
- It is more resource-intensive than the serial garbage collector, but it is able to collect garbage more quickly.
- CMS (Concurrent Mark Sweep) garbage collector
- This is a concurrent garbage collector that is designed for applications with large heap sizes and long pause times.
- It is able to perform garbage collection concurrently with the application, which minimizes the impact on application performance.
- G1 (Garbage First) garbage collector
- This is a garbage collector that is designed for applications with large heap sizes and high levels of object allocation.
- It is able to divide the heap into smaller regions and collect garbage concurrently. Which minimizes the impact on application performance.
In addition to these garbage collectors, there are several other garbage collectors available in Java, including:
- The ZGC garbage collector and
- The Epsilon garbage collector.
Conclusion
It is important to note that garbage collection is not a solution or a kind of remedy. It is not always possible to completely eliminate the need for manual memory management in Java. However, with careful planning and the use of appropriate garbage collectors, it is possible to greatly reduce the burden of memory management and improve the performance of your Java applications. As a Java developer writing code for more than a decade, I always let JVM do the job by itself. Hence, I would recommend the same to others. There may be some exceptions to customize but if you are a beginner then it is good to let JVM handle everything.