This content originally appeared on DEV Community and was authored by Chibueze felix
Hello Felix what do you understand by “MUTEX”?
Yes, that was the question that was thrown at me on one those interviews days I had in the past, and it got me stuttering
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I honestly responded that I had not idea what that is
. And yes, honesty is good however, every software engineer is expected to know some basic concepts; especially those that are core to the system on which most software is runs -an Operating system.
The operating system is the core software of every device, it the parent software on which other software runs; that is the most basic definition I could get for an operating system.
Being the core of every other operations that happens on a system(system here can be a server, a phone, a Payment terminal etc), it is expected that data is stored, processed and easily accessible in the best ways ways possible. However, for this efficiency to be achieved by any software engineer it is expected that one understands some basic concepts related to the operating system(OS).
A good understanding of these concepts will make you a better engineer and this will be evident in what data types you utilise and the in your algorithms to access or process data efficiently.
In this article we will provide clarity to a few operating system concepts these include:
- Stacks
- Heaps
- Threads
- Mutex
- Scheduling
Please note that these are just a few OS concepts and We can not exhaust all in one article as it is intended to be as short and possible to clarify these handpicked topics 
. Lets get to it.
Stacks
A stack is a last-in, first-out (LIFO) data structure that plays a key role in operating systems. Think of it like a stack of plates—adding or removing items only happens at the top. In programming, the call stack keeps track of function calls, storing return addresses and local variables. When you call a function, the OS pushes a new frame onto the stack; when the function returns, that frame gets popped off. Exceeding the allocated stack memory—often due to infinite recursion—results in a stack overflow. Stacks provide fast and predictable memory allocation, making them essential for function execution.
Heaps
Heaps are used by OS memory managers for dynamic memory allocation. Unlike stacks, heaps allow flexible allocation and deallocation, though at the cost of efficiency. When a program calls malloc() or new, memory is allocated from the heap. Over time, repeated allocation and deallocation can lead to fragmentation, making memory usage less efficient. To combat this, modern OSes use strategies like buddy allocation and slab allocation. A common issue with heap memory is memory leaks—when allocated memory isn’t freed, it slowly consumes system resources, potentially leading to performance degradation or crashes.
Threads
A thread is the smallest unit of execution that an OS scheduler manages. If a process is a running program, threads are independent execution paths within that process. Since threads share the same memory space but have separate execution stacks, they enable concurrent execution without the overhead of creating new processes. OSes support kernel threads (managed by the OS) and user threads (managed by libraries like pthreads). Multithreading is crucial for taking advantage of modern multicore processors, improving responsiveness and parallelism. Since thread context switching is lighter than process switching, threads are an efficient way to handle multiple tasks concurrently.
Mutex
A mutex (short for mutual exclusion) is a synchronisation mechanism that ensures only one thread accesses a shared resource at a time. Think of it like a bathroom key—only one person can hold it at a time, and others have to wait. Mutexes prevent race conditions, where multiple threads modifying shared data simultaneously can lead to unpredictable results. However, they need to be used carefully—improper usage can lead to deadlocks (where threads are stuck waiting for each other) or priority inversion (where a low-priority thread holds up a high-priority one). Thoughtful mutex design is key to writing thread-safe concurrent programs.
Scheduling
Scheduling determines how the OS assigns CPU time to threads. The goal is to balance performance, fairness, and responsiveness. Common scheduling strategies include round-robin (giving each thread a fixed time slice), priority-based (favoring higher-priority tasks), and multilevel feedback queues (dynamically adjusting priorities based on behavior). Real-time operating systems take scheduling further by guaranteeing response times for critical tasks. Every time the OS switches from one thread to another, a context switch occurs, which involves saving and restoring CPU state. Efficient scheduling is essential for ensuring smooth system performance and optimal resource utilisation.
These concepts provide basic insights into data types and the operations used in basically all Operating systems, feel free to research more on other concepts related to the OS such as Security, Memory management, Concurrency,Interrupt, Kernel.
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Thanks for your time !!!
This content originally appeared on DEV Community and was authored by Chibueze felix