Thread

• A thread is also called a Lightweight Process.
• Each thread belongs to exactly one process and no thread can exist outside a process.
• But, one process can contain multiple threads.
• Each thread represents a separate flow of control, thread is a path of execution within a process.
• A thread is a flow of execution through the process code, with its program counter that keeps track of which instruction to execute next, system registers that hold its current working variables, and a stack that contains the execution history.
• Threads are generally used to improve the application through Parallelism.
• In the operating system, there are two types of threads:
  • Kernel-level Thread
  • User-level Thread
• Advantages of a thread depending on the type of thread.

Let's see the advantages of threads according to their types.

Advantages of Kernel-level Thread:

• Multiple threads of the same process can be scheduled on different processors.
• The routines of the kernel can also be multithreaded.
• If a kernel-level thread is blocked, another thread of the same process can be scheduled by the kernel.
• These threads are fully aware of all other threads.
• Hence, Scheduler may decide to give more time to a process having a large number of threads than a process having a small number of threads. -These threads are good for applications that frequently block.

Advantages of User-level Thread:

• Implementing threads at user space is easier and faster to create than threads at the kernel level.
• They can also be more easily managed.
• These threads can be run on any operating system.
• It does not need any support from the kernel-level threads.
• The overall process is quick and effective because there is no requirement for a system call.
• No need for the kernel-mode privileges for the thread to switch in userspace.
• The organization is straightforward because the threads are produced, switched, and controlled without interference from the kernel.
• Do not require modification to operating systems.