What is the system function fork?

ByIshita Juneja
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The fork system call is a fundamental operation in many operating systems, playing a pivotal role in process creation. A process that uses the fork system call effectively creates a new process that is known as the child process. 

 

The parent process and the newly formed child process run simultaneously as a result of this action, which duplicates the caller process.

 

In this blog, we will learn about the functioning of forks in operating systems. We will also learn about the best operating system courses available to help you better grasp the essential concepts.

 

Basic Functionality and Characteristics of Fork

 

  • Creation of a New Process: The primary purpose of the fork system call is to generate a new process. This operation allows for the parallel execution of multiple tasks within an operating system.

 

  • Duplication of the Calling Process: Upon invoking the fork in operating systems, the entire calling process is duplicated to create the child process. This includes copying the parent operation’s open file descriptors, memory space,  and other necessary properties.

 

  • Child Process Characteristics: The child process is an exact replica of the parent process at the point of the fork call. It possesses its own Process ID (PID) and operates independently of the parent operation.

 

  • Copy-on-Write Mechanism: The fork system call optimizes memory usage through the copy-on-write mechanism. Initially, the child and parent processes share the same physical memory pages. A separate copy is created only when one of them modifies a shared memory page.

 

  • Return Value: Both the child and parent processes receive vital information from the return value of the fork call. The function is executed in the child process if the return value is zero. A positive number denotes the child process’ PID, but a return value of -1 denotes an error.

 

Basic Terminologies Associated with Fork

 

  • Process: A process is an instance of an active program in the context of operating systems. With its own resources, CPU, I/O devices, memory, and files, it is a separate entity.

 

  • Parent Process: The parent process is the process that initiates the fork system call, which results in the formation of a new child process. The parent process continues to execute after the call for the fork in an operating system is made.

 

  • Child Process: The newly created process that inherits the attributes of the parent process but operates independently.

 

  • Process ID (PID): A process ID is a unique identifier assigned by the operating system to each process. It distinguishes one process from another.

 

  • Complete Process Duplication: When the operating system calls fork, it copies the whole parent process in order to form a new child process. This involves copying open file descriptors, RAM, and other pertinent data.

 

  • Copy-on-Write Optimization: The copy-on-write strategy optimizes memory usage by allowing the child and parent processes to share the same physical memory initially. 

 

  • Return Value Usage: The return value of invoking the fork in operating system is crucial for determining the execution path. If the return value is 0, the code is executed in the child process. A return value of -1 indicates an error, while a positive value represents the child process’ PID.

 

Pros of fork System Call

 

  • Concurrent Execution: By creating new processes, the system call for fork in operating system and facilitates concurrent execution, improving system performance and multitasking capabilities.

 

  • Code Reuse: The child process receives an identical copy of the parent process, promoting code reuse and simplifying the development of complex programs.

 

  • Memory Optimization: Copy-on-write optimization minimizes initial memory expenditure, as child and parent processes have access to the same physical memory pages until modifications are made.

 

  • Process Isolation: Each process started by the fork system call has a separate memory area and set of tools, enhancing system security and stability by preventing interference between processes.

 

Cons of fork System Call

 

  • Memory Overhead: Despite copy-on-write optimization, the system call for the fork in operating system incurs memory overhead as the entire parent process is initially copied, increasing memory usage.

 

  • Resource Duplication: A process’s fork can result in resource waste and inefficiencies since the child process copies all open network connections, file descriptors, and other resources.

 

  • Complexity of Communication: The independent processes created by the fork system call may require coordination and communication.Complexity may increase if interprocess communication techniques like pipes or shared memory are used.

 

  • Impact on System Performance: Forking a process repeats resource management, memory allocation, and other system operations, which may affect system performance, particularly in situations where processes start and stop often.

 

Let us now move on to the next part of this blog i.e., Operating system courses.

 

Operating system courses

 

Best Operating System Course Online (Coding Ninjas)

 

The Operating Systems course offered by Coding Ninjas is a comprehensive program designed to prepare learners for software engineering interviews. With a 4.8 rating and endorsements from successfully placed students, it covers key concepts with over 150 problems, ensuring a thorough understanding of real-world applications.

 

Introduction to Computers and Operating Systems and Security by Microsoft (Coursera)

 

This 4-week course provides an excellent entry point for those aspiring to begin a career in cybersecurity. Covering computers, operating systems, enterprise systems, and security, it prepares students for the SC-900 exam. The course is well-structured and caters to beginners, making it accessible to a wide audience.

 

Introduction to Hardware and Operating Systems by IBM (Coursera)

 

Designed for IT beginners, this 7-week course from IBM covers hardware, operating systems, and troubleshooting. It serves as an excellent foundation for those pursuing CompTIA ITF+ and A+ certification exams. The practical approach, coupled with IBM’s expertise, makes this course valuable for anyone entering the IT field.

 

Advanced Operating Systems by Georgia Institute of Technology (Udacity)

 

This course delves into the advances that have shaped modern operating systems. Covering a variety of platforms such as cell phones, multi-core systems, parallel systems, distributed systems, and cloud computing, it provides a deep understanding of the state-of-the-art in operating system design. The association with Georgia Tech adds credibility to the course.

 

Introduction to Operating Systems by Georgia Institute of Technology (Udacity)

 

Geared towards teaching basic operating system abstractions, mechanisms, and implementations, this 8-week course is suitable for both beginners and those looking to deepen their understanding of operating systems. The practical knowledge gained from this course is valuable for anyone pursuing a career in systems programming or software development.

 

Conclusion

In conclusion, mastering the concept of fork in operating systems is pivotal for effective process creation and parallel execution. This fundamental aspect, explored in an operating system course, empowers learners to understand the intricacies of process duplication and memory management.