Published: 22 Aug 2025 | Reading Time: 5 min read
The multithreading paradigm is an essential aspect of effective application execution and resource utilization. Threads enable an operating system to run several tasks cooperatively in a single process and hence enhance program performance and responsiveness. This article discusses the thread concept, components of threads, types, benefits, as well as operating system threading problems.
A thread is viewed as the smallest execution unit in processes. A process may have either a single or multiple threads. One thread executes independently as part of the program. All threads in a process have common access to valuable resources such as memory space and open files, but they all have private stacks, program counters, and registers. Threads are also referred to as lightweight processes based on independent runtime and resource sharing.
There are three components of thread in the operating system:
Threads provide several advantages in operating systems and programming, including:
The threads can be divided into two categories:
There are several issues with threading such as:
In many Unix-like operating systems, two basic system calls are defined for process creation and management:
It expresses the case where a thread is terminated before completing a given task, with the following being significant forms:
In Unix-based systems, signals notify a process of particular events. They can be divided into two groups:
Threaded applications must manage such signals so that a signal directed to a thread does not interfere or is delivered to another thread.
A thread pool refers to successfully predetermined threads used to execute any incoming tasks. This process makes creating a new thread for each task unnecessary because the threads are simply picked up from the pool whenever required. Thread pools are especially useful when tasks are frequent because the thread creation and destruction would incur a considerable cost.
In multithreading, thread-specific data denotes data that are unique to each thread. This allows the independent operation of each thread without disturbing others, even if they share the same process. Thread-specific data is found in systems where separate threads carry out different tasks or operations that need isolated data (for instance, transaction IDs in a financial application).
Process Synchronization refers to the mechanisms that ensure multiple processes or threads can safely concurrently access shared resources without conflict. This is particularly significant in a multithreading environment in the case of a race condition which results in the timing of threads' access to shared data.
Race condition arises when two or more threads access the shared data concurrently, and the result depends on when each thread executes. The behaviour could be inconsistent and could provide wrong results. Race conditions are generally smothered via synchronisation mechanisms like mutexes and semaphores.
A mutex is a synchronisation primitive that provides access to a resource in mutual exclusion. To prevent a race condition, it is ensured that only one thread will own the critical section while delivering the desired access to the resource. Whenever a thread accesses a resource, it must "lock" the mutex and "unlock" it when finished, allowing other threads to access the resource.
In the simplest terms, a deadlock is when two or more threads are blocked forever, waiting for another to release a resource. Deadlocks are a serious issue in multithreaded programming because they usually can lock up applications. Deadlock prevention strategies involve several techniques, including ensuring resource acquisitions are done in a specific order and implementing timeouts.
Here are the differences between process and thread:
| Aspect | Process | Thread |
|---|---|---|
| Definition | A process is an independent program in operation. | A thread is the smallest unit of execution within a process. |
| Resource Allocation | Each process has its own resources (memory, CPU, etc.) | Threads share resources (memory, code) within the same process. |
| Creation Speed | Slower to create and terminate due to the allocation of resources. | Faster to create and terminate due to the sharing of resources. |
| Memory Space | Each process has its own memory space. | There is a shared memory space between threads within a process. |
| Communication | Communication between processes is slower and requires IPC (Inter-Process Communication). | Communication between threads is faster because they share the same memory space. |
| Independence | Processes are independent of one another. | Threads are interdependent and capable of accessing one another's data. |
| Failure Impact | Failures of one process do not impact other processes. | When a thread fails, it may affect several threads within the same process. |
| Example | Opening two applications (such as two web browsers). | Opening two tabs in the same browser. |
Here are the advantages of threading in the operating system:
In conclusion, threads in an operating system form a vital feature to execute various operations concurrently within a process for better performance with resource efficiency. Such benefits include faster context-switching, less resource consumption, etc., whereas the challenges include race conditions, deadlocks, and problems with synchronisation. To create efficient multithreaded applications, properly managing thread pools, mutexes, and thread-specific data is critical in building usable and stable applications. The ability to manage the complexity of multithreading allows applications to operate using the resources offered by modern operating systems and hardware.
Multithreading allows several threads to be executed concurrently by a single process, enhancing performance by allowing parallel tasks. It improves responsiveness and resource utilisation through the work into smaller concurrent threads.
The disadvantages of threads in os include added complexity, overhead for synchronisation, and the possibility of deadlocks. Managing too many threads can waste resources, and debugging becomes harder due to non-deterministic behaviour, making multithreading very hard to maintain.
The issues with multithreaded programming include problems with race conditions, deadlocks, and other synchronisation issues. Multithreading increases complexity, resource consumption, and debugging difficulty, leading to problems in managing and maintaining efficient code.
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Source: NxtWave (CCBP.in)
Original URL: https://www.ccbp.in/blog/articles/threading-issues-in-operating-system