Fork System Call in Operating System

In many operating systems, the fork system call is an essential operation. The fork system call allows the creation of a new process. When a process calls the fork(), it duplicates itself, resulting in two processes running at the same time. The new process that is created is called a child process. It is a copy of the parent process. The fork system call is required for process creation and enables many important features such as parallel processing, multitasking, and the creation of complex process hierarchies.

It develops an entirely new process with a distinct execution setting. The new process has its own address space, and memory, and is a perfect duplicate of the caller process.

Basic Terminologies Used in Fork System Call in Operating System

• Process: In an operating system, a process is an instance of a program that is currently running. It is a separate entity with its own memory, resources, CPU, I/O hardware, and files.
• Parent Process: The process that uses the fork system call to start a new child process is referred to as the parent process. It acts as the parent process’s beginning point and can go on running after the fork.
• Child Process: The newly generated process as a consequence of the fork system call is referred to as the child process. It has its own distinct process ID (PID), and memory, and is a duplicate of the parent process.
• Process ID: A process ID (PID) is a special identification that the operating system assigns to each process.
• Copy-on-Write: The fork system call makes use of the memory management strategy known as copy-on-write. Until one of them makes changes to the shared memory, it enables the parent and child processes to share the same physical memory. To preserve data integrity, a second copy is then made.
• Return Value: The fork system call’s return value gives both the parent and child process information. It assists in handling mistakes during process formation and determining the execution route.

Process Creation

When the fork system call is used, the operating system completely copies the parent process to produce a new child process. The memory, open file descriptors, and other pertinent properties of the parent process are passed down to the child process. The child process, however, has a unique execution route and PID.

The copy-on-write method is used by the fork system call to maximize memory use. At first, the physical memory pages used by the parent and child processes are the same. To avoid unintentional changes, a separate copy is made whenever either process alters a shared memory page.

The return value of the fork call can be used by the parent to determine the execution path of the child process. If it returns 0 then it is executing the child process, if it returns -1 then there is some error; and if it returns some positive value, then it is the PID of the child process.

Fork() System call

Advantages of Fork System Call

• Creating new processes with the fork system call facilitates the running of several tasks concurrently within an operating system. The system’s efficiency and multitasking skills are improved by this concurrency.
• Code reuse: The child process inherits an exact duplicate of the parent process, including every code segment, when the fork system call is used. By using existing code, this feature encourages code reuse and streamlines the creation of complicated programmes.
• Memory Optimisation: When using the fork system call, the copy-on-write method optimises the use of memory. Initial memory overhead is minimised since parent and child processes share the same physical memory pages. Only when a process changes a shared memory page, improving memory efficiency, does copying take place.
• Process isolation is achieved by giving each process started by the fork system call its own memory area and set of resources. System stability and security are improved because of this isolation, which prevents processes from interfering with one another.

Disadvantages of Fork System Call

• Memory Overhead: The fork system call has memory overhead even with the copy-on-write optimisation. The parent process is first copied in its entirety, including all of its memory, which increases memory use.
• Duplication of Resources: When a process forks, the child process duplicates all open file descriptors, network connections, and other resources. This duplication may waste resources and perhaps result in inefficiencies.
• Communication complexity: The fork system call generates independent processes that can need to coordinate and communicate with one another. To enable data transmission across processes, interprocess communication methods, such as pipes or shared memory, must be built, which might add complexity.
• Impact on System Performance: Forking a process duplicates memory allocation, resource management, and other system tasks. Performance of the system may be affected by this, particularly in situations where processes are often started and stopped.

Conclusion

In conclusion, the fork system call in operating systems offers a potent mechanism for process formation. It enables the execution of numerous tasks concurrently and the effective use of system resources by replicating the parent process. It’s crucial for the creation of reliable and effective operating systems to comprehend the complexities of the fork system call.

FAQs on Fork System Call

Q1: What is the fork system call?

Answer:

The fork system call creates a new process(i.e Child Process) by duplicating the existing process(i.e Parent Process)

Q2: How is the fork system call used?

Answer:

The fork system call is invoked in a program to create a child process.

Q3: What is the return value of the fork system call?

Answer:

It returns the process ID of the child to the parent and 0 to the child.

Q4: What is the purpose of using the fork system call?

Answer:

The fork call allows for the creation of a new process that can perform tasks independent of the parent process.