What is CLR Garbage Collection?

Quick Overview:
Here, we’ll be exploring the fundamentals of garbage collection mechanisms in the common language runtime of .NET technology. You will gain an understanding of the garbage collector’s generation, benefits, and memory concepts, such as release and allocation from the unmanaged heap. Thus, a strong foundational knowledge base is offered.

CLR Garbage Collection

The garbage collection mechanism stands as a foundational pillar of CLR in improving its workflow and application performance. Mainly, it’s a part of the memory management component, and it handles the managed heap that is configured for new and currently ongoing objects.

It’s highly recommended that a dotnet developer learn what CLR garbage collection is. Here, we are helping you understand its fundamentals in the minimal time possible. So, let’s get started.

CLR Garbage Collection: A Brief Walkthrough

If you go through the components of common language runtime (CLR), you’ll find garbage collection as one of its main components. It primarily helps with memory management so that all the objects have sufficient memory resources to execute the operations seamlessly.

In addition, garbage collection (GC) focuses on allocating and deallocating the memory to an application. Moreover, if you are a developer working with managed code, then this garbage collection mechanism reduces your efforts. It automatically manages the memory by preventing memory leaks and freeing memory from an object.

Furthermore, below are the core benefits of garbage collection.

• It reduces the workload and efforts of developers to configure manual memory management.
• It automatically handles the managed heap and ensures enough resources are available for all processes.
• If it finds an object in an inactive state, the garbage collection mechanism reclaims the allocated memory and uses it for other objects.
• It also offers safety by guaranteeing that an individual object doesn’t utilize memory allocated to some other object.

The CLR GC Fundamentals For Developers

Before you start to configure or optimize the CLR garbage collection, you should understand the following three primary aspects.

1: Memory concepts

Whenever you have to develop a dotnet application, virtual address space should be utilized instead of the device’s physical memory; it helps the CLR efficiently free and allocate the memory and perform associated operations on the managed heap.

In addition, virtual memory works in three different states: free, reserved, and committed. When a new object gets created, a unit of free memory is allocated to it. Further, the reserved state doesn’t work with GC operations, as it only stores the data. Lastly, the committed state storage refers to the physical memory.

2: Memory allocation

As you know, the garbage collection mechanism uses a managed heap for allocating memory. However, this managed heap is not initially available. When a new process gets initialized, the runtime comes into action and reserves a contiguous address space. This space is known as a managed heap.

Further, whenever an object gets created, the CLR allocates the space available in the managed heap. All the objects are referenced and placed following the other using a pointer. Due to this, the managed heap performs faster than unmanaged memory, and the application performance skyrockets.

3: Memory release

One of the main functions of a garbage collector is to release the memory. The GC constantly monitors the application and objects being utilized. If it finds an object that no longer utilizes the allocated memory, it executes the deallocation procedure to reclaim that memory chunk.

Furthermore, in order to execute the release process, the garbage collector analyzes the application roots, including the local variables, static fields, thread stack, CPU registers, queue, and GC handles. Following the analysis, a graph is generated and taken as a reference to reach objects and free memory.

When Does Garbage Collection Initiate Operations?

The garbage collector component of CLR is initiated during some specific scenarios, as listed below. Any one of the following three conditions must be true; otherwise, it’ll remain inactive.

Scenario #1: Low Physical Memory

If the system detects and indicates a low physical memory, the garbage collector starts its operation to free memory and retain stability. In addition, even if the host indicates a low memory, then also GC does the same.

Scenario #2: Threshold Surpass

When the memory gets allocated from the managed heap, the processes continuously adjust. Sometimes, the threshold surpasses the acceptable limit. If such a condition occurs, the garbage collector initializes its operations.

Scenario #3: Calling of the “GC.Collect” method

The “GC.Collect” method gets used quite rarely, specifically for testing purposes. But whenever it’s called in the program, the garbage collector has to work accordingly. However, the garbage collector runs constantly in the background, making this method only available for development environment purposes.

The GC Generations and Algorithm

To work in the most efficient way, the garbage collector has divided the object handling into three generations: Generation 0, 1, and 2. As long as the object lives, it gets promoted to the next generation, as the entire generation concept relies on short and long-lived objects.

In addition, among all three, the youngest is Generation 0, as whenever the object gets created, it resides in this generation. Moreover, if the application knows that an object is short-lived, such as a temporary variable, it also gets put into this generation only.

Furthermore, in generation 1, those objects reside and are detected as a buffer between short- and long-lived objects. Sometimes, even a generation 0 object is promoted to generation 1 if its memory utilization duration increases.

Lastly, we have generation 2, where only long-lived objects reside. All these objects are retained until the garbage collector determines them as unreachable.

Concluding Up

The garbage collector in CLR performs crucial operations that help in efficient memory management. It works in collaboration with the managed heap, which gets utilized to allocate memory to running objects. In addition, it also supports optimizing application performance by freeing the memory from objects in a non-active state. If you also have a dotnet application or are looking to develop one, always ask the developer to modify the GC configuration accordingly for the best-in-class results.