Garbage Collection Is An Automatic Process Used In Memory Management Programming Languages ​​To Collect And Delete Objects Without Using Memory. 

When a programmer creates objects, they are placed in memory, and the program may no longer use them. In this case, these objects are known as “garbage.”

In the garbage collection process, the garbage collector identifies and removes objects no longer used in the application. This process is done automatically; the programmer does not need to delete those objects manually. These operations play an important role in memory optimization and help reduce the possibility of errors that may occur due to a lack of memory.

How does garbage collection work?

As we mentioned, Garbage collection is an automatic process to collect and remove inappropriate objects from memory. To do this, a GC system continuously checks the program memory and tries to identify and remove from memory objects that are no longer used by the program.

GC uses a special algorithm in this work. The GC algorithm is divided into two categories: the first category is generation-based algorithms, and the second category is marked and sweep-based algorithms.

Generation-based algorithms divide memory objects into multiple generations. New things are placed at a young age, and items still in memory after several GC cycles are set in old age. Considering that most things are short-lived and placed at a young age, this algorithm examines this generation more for garbage collection.

In algorithms based on mark and sweep, the GC system first marks all the objects left in memory. Then, it removes all the unchecked things. This algorithm is suitable for checking large and more complex memories.

In any case, the GC is done automatically, and the programmer does not need to remove the garbage manually. This operation optimizes memory and helps to reduce the possibility of errors that may occur due to problems in memory management.

Types of Garbage Collection Methods

When the GC system collects garbage memory, it uses several methods to remove unused objects. Some of the main methods used in this field are as follows:

1. Mark-and-Sweep

In this method, the GC first marks all objects left in memory. Then, it keeps the unmarked objects as garbage and removes them. This method is suitable for applications that use large memory.

2. Copying

In this method, the memory is divided into two parts. In the first part, live objects (in active state) are placed, and dead things (no longer used) are identified in the second part. In each cycle, an amount of the memory is freed, and live objects are transferred to that part. This method has high performance for applications that use little memory.

3. Reference Counting

In this method, each object is assigned a counter that counts the number of references to it. When an object’s reference count reaches zero, the thing is considered garbage and removed from memory. This method is mainly suitable for programming languages ​​with automatic memory management.

4. Incremental

In this method, garbage collection is done in stages and at specific times. The above process is suitable for programs that use a large memory because it continuously evaluates the memory.

What types of programs use the Mark-and-Sweep method?

The Mark-and-Sweep method is one of the most common and widely used garbage collection methods. This method is useful for programs that use significant memory in a complex way and for languages ​​that support automatic memory management.

Applications for which the above method has acceptable performance are graphical applications, system applications, web applications, games, etc. For example, web browsers usually use this method for memory management. Also, programs written in programming languages ​​such as Python that support automatic memory management commonly use this method.

Using the Mark-and-Sweep method in programs with a large memory leads to a reduction in memory consumption and an improvement in the application’s performance. Also, this method automatically helps the programmer avoid errors related to memory management, such as allocating extra or not freeing memory after use.

Is the Incremental method suitable for applications with low memory?

The incremental method is one of the methods of garbage collection, which, of course, is not very suitable for programs with a small amount of memory. For this reason, the above method is ideal for programs with a large amount of memory and need to collect garbage at specific times.

In the incremental method, garbage collection is done continuously and at specific times. This method is mainly used to reduce the time required for garbage collection. However, this approach increases processing overhead, as application processing may be temporarily halted during garbage collection. Therefore, in programs with a small amount of memory, using this method may reduce the program’s performance.

In general, to select the appropriate GC method, one needs to consider the application’s needs and characteristics and then choose the best performance method.

Is there another way to do garbage collection in low-memory applications?

The reference counting method is another method used for garbage collection in programs with low memory volume.

In the reference counting method, each object is assigned a counter that counts the number of references to it. When the number of references to an object becomes zero, the thing is considered garbage and removed from memory. This method is suitable for applications with a small amount of memory because it effectively frees the memory used.

However, there are also problems associated with the above method. For example, if two objects have a reference to each other (i.e., a reference circle), this method will not be able to identify and remove this reference circle. Also, this method consumes more memory because it requires allocating a counter for each object.

Can multiple GC methods be used in combination in a program?

Yes, in some cases, it is possible to use multiple GC methods in a single program in a mixed manner. This method is known as Hybrid GC.

Different application parts are managed using different GC methods in the Hybrid GC method. For example, details of the program with large memory footprints can be handled using the Mark-and-Sweep method. Other sections with less memory size can be managed using the Reference Counting method. In this way, combining these two methods makes it possible to obtain more optimal performance and more appropriate memory consumption in the program.

However, using Hybrid GC requires precision and intelligence in program design and implementation. Because combining different GC methods may cause problems such as unwanted synchronicities in garbage collection. Therefore, you need detailed and thorough tests to use Hybrid GC.

Do all programming languages ​​use GC?

No In fact, some programming languages, ​​such as C and C++, do not support GC, and programmers must manually manage memory.

For example, in the C language, the programmer must manually free the memory that has been allocated. This is done using functions like malloc and free. In C++, the concept of destructors is also used to release memory manually.

Additionally, some programming languages, ​​such as Rust, use a powerful memory management system that automatically manages memory, but not in the usual GC way.

Therefore, using GC helps programmers avoid memory management separately and generally improves program performance and reduces memory errors.

What languages ​​support garbage collection?

Many modern programming languages support garbage collection. Some of these languages ​​are:

1. Java: Java programming language version 1.1 and later uses GC. In Java, GC is automatically called periodically.
2. C #: C# programming language also supports GC. In C#, GC is called automatically when a new object is created.
3. Python: Python programming language also supports GC. In Python, GC is called automatically and can be called manually.
4. Ruby: The Ruby programming language also supports GC. In Ruby, GC is automatically called when a new object is created.
5. JavaScript: It is called automatically in GC JavaScript programming language.
6. PHP: The PHP programming language also automatically calls GC when creating a new object.
7. Swift: Swift programming language also calls GC automatically when creating a new object.

Advantages of Garbage collection

Garbage collection  provides various advantages to programmers, some of which are as follows:

1. Increased productivity: GC allows programmers to focus on the logic of their program without managing memory. The above approach will make programmers more productive by focusing on program logic.
2. Reduction of memory errors: By using GC, programmers do not need to manage memory manually, reducing the possibility of memory errors.
3. Reduced development time: By using GC, programmers do not need to spend time on memory management, and because of this, the development time of programs is reduced.
4. Increased security: Using GC reduces the possibility of memory and security errors. Because GC constantly checks the memory and removes garbage objects, it plays an important role in exposing sensitive information.
5. Reduced development cost: By using GC, programmers do not need powerful hardware equipment for memory management, thus reducing the cost of development and support.

In general, GC helps programmers to focus on their application logic without memory management, which increases productivity, reduces memory and security errors, reduces development costs, and reduces application development time.

Disadvantages of Garbage collection

While Garbage collection provides significant advantages to programmers, it also has disadvantages, some of which are as follows:

1. Slowness: GC constantly checks memory to remove unused objects, which may slow down the execution of the application. So, for some programs needing fast performance, using GC is unsuitable.
2. System resource consumption: GC requires system resources to delete objects without using memory. This means that GC may cause excessive system resource consumption for some systems.
3. Memory discontinuity: GC does not allow programmers to precisely monitor the memory management process and determine which objects remain in memory and which are removed from memory. The same issue may cause memory discontinuity, which in some cases increases the program’s response time.
4. Problems with middleware: In some cases, GC may interfere with middleware running other programs and cause system problems.

In general, using GC for memory management has advantages and disadvantages that programmers should consider. If you need speed and less resource consumption for your application, using GC may not be suitable.