First Come, First Served


First Come, First Served (FCFS) is a term used in computing to refer to a scheduling algorithm. This algorithm deals with tasks in the exact order that they arrive or request service, with the one arriving first being handled and completed before the next one that comes in. Essentially, it operates on a first-come, first-served basis, much like a queue in a supermarket.


The phonetic transcription of “First Come, First Served” is:/ˈfɜːrst kʌm, ˈfɜːrst ˈsɜːrvd/

Key Takeaways

  1. Definition: First Come, First Served (FCFS) is a system wherein the customers or tasks arriving first will be taken care of first. It is an operating principle that has extensive utility in various fields, including customer service, inventory management, and queues in restaurant waiting lines, amongst others.
  2. Pros and Cons: While the FCFS system is fair and easy to understand, it can lead to inefficiencies or delays as certain tasks may take longer than others, resulting in what is referred to as the “convoy effect.” Moreover, in cases where all tasks or individuals are not equally important, prioritization cannot be executed in the FCFS model.
  3. Applications: Despite certain limitations, the FCFS principle is widely used. It is frequently adopted in CPU scheduling in computing, disk scheduling, network scheduling, in queues at supermarkets, banks, call centers, and customer service desks. FCFS is a baseline model which is sometimes modified according to the specific needs of an organization or a sector.


The technology term “First Come, First Served” (FCFS) is significant as it represents a crucial scheduling policy used in various computing systems and networks. This policy ensures that all processes are treated in the sequence they occur or in the order of their arrival, with the policy strictly adhering to the arrival sequence of such requests. In both operating systems scheduling processes and network traffic management, the FCFS rule plays a vital role. It simplifies scheduling decision making, reduces complexity, and ensures fairness to a reasonable extent. However, it’s important to note that while FCFS is easily understandable and implementable, it can lead to a phenomenon called ‘convoy effect,’ which can result in inefficiencies in resource utilization.


The term “First Come, First Served” (FCFS) is a scheduling policy commonly used in computing and technology. It is primarily used in managing processes within various computing environments like operating systems, disk scheduling, networking scheduling, or website server requests. This process scheduling algorithm simply queues processes in the order in which they request service and serves them in the same sequence. FCFS operates on the principle that the process that first requests attention should be the first one to receive the resources and services.The fundamental purpose of the First Come, First Served principle is to ensure equal resource sharing and prevent process starvation – a situation where a process indefinitely waits for resources. It is straightforward and doesn’t require complicated logic to implement. In networking scheduling, for example, FCFS can determine the order in which packets of data are transmitted from a server to ensure smooth traffic flow. On the downside, although simple, FCFS can lead to long waiting times if a large request precedes a batch of smaller ones, making it less efficient for tasks that require intense computational resources.


1. Customer Service Lines: In most retail stores, banks, or restaurants, customers are typically served on a first come, first served basis. When a customer enters the store or gets in line, they are served in the order they arrived, regardless of what products or services they are looking for.2. Event Ticket Sales: Many events, such as concerts or sporting events, sell tickets on a first-come, first-served basis. When tickets go on sale, the first people to buy them secure their spots, and once all the tickets have been sold, no more are available. This often means the people who commit to buying tickets earliest get the best seats or positions.3. Public Services or Amenities: In many public services like clinics, hospitals or government offices, services are often provided on a first come, first served basis. Hospital emergency rooms often operate on this principle, with exceptions made for patients in critical conditions. If two patients arrive with similar conditions, the patient who arrived first will be seen first. Another example could be public parks, where amenities such as picnic tables or BBQ grills are offered on a first-come, first-served basis. People can’t reserve these amenities ahead of time, and whomever arrives first can use them before others.

Frequently Asked Questions(FAQ)

Sure, here it goes.**Q1: What is meant by ‘First Come, First Served’ in technology?**A1: In technology, ‘First Come, First Served (FCFS)’ is a policy used in CPU scheduling. It implies that the process which arrives first gets executed first by the CPU. Essentially, the scheduling is done in the order as they arrive in the ready queue.**Q2: Where is the ‘First Come, First Served’ policy mainly used?**A2: ‘First Come, First Served’ is mainly used in CPU scheduling where it determines the order of jobs based on their arrival time.**Q3: What are the benefits of using ‘First Come, First Served’ scheduling?**A3: FCFS scheduling is simple to understand and easy to implement. It is fair in a way that the process that arrives first gets served first, avoiding favoritism or priority bias. **Q4: What are the drawbacks of ‘First Come, First Served’ scheduling?**A4: FCFS can lead to a problem known as the convoy effect, where small processes get stuck behind large ones, causing wait times to increase, which can slow down the overall system performance. It doesn’t take into account the priority of processes, hence it is non-preemptive.**Q5: Is the ‘First Come, First Served’ policy always the most efficient method?**A5: No, FCFS policy is not always the most efficient. For example, in case of CPU scheduling, if a longer process arrives first, shorter processes will have to wait leading to higher average waiting time. Other scheduling algorithms like Shortest Job Next or Priority Scheduling might be more efficient in some cases. **Q6: Is ‘First Come, First Served’ the same as ‘First In, First Out’ (FIFO)?**A6: Yes, in many cases ‘First Come, First Served’ is the same as ‘First In, First Out’ (FIFO). Both these terms mean that the first item to arrive is the first one to be removed or processed. In the field of computer science, both these terms are often interchangeable. **Q7: Can ‘First Come, First Served’ policy be used in areas other than CPU scheduling?**A7: Yes, ‘First Come, First Served’ policy is a principle that can be applied in many other scenarios including disk scheduling, memory management, network scheduling and more.

Related Finance Terms

  • Job Scheduler
  • Queuing Theory
  • Non-preemptive Scheduling
  • Concurrency Control
  • Process Scheduling

Sources for More Information

Table of Contents