A thread is a segment of code that can execute independently, allowing programs to perform multiple tasks simultaneously. There are two types of threads: single thread, which executes one task at a time, and multiple threads, which can handle concurrently running tasks, leading to benefits like responsiveness, resource sharing, and scalability. Thread management can be user-level, managed by applications, or kernel-level, managed by the operating system, with different multithreading models available depending on the relationship between user and kernel threads.

1. Submitted by
Kiran Patel

2. What is Thread
A thread is a portion of code that may be executed
independently of the main program.
For example, a program may have an open thread waiting
for a specific event to occur or running a separate job,
allowing the main program to perform other tasks.
A program is capable of having multiple threads open at
once and will either terminate or suspend them after a task
is completed, or the program is closed.

3. Type of Thread
There are two type of thread:-
Single Thread
Multiple thread

4. Single Thread:-
A single-thread, only one task can be done at a time and the program
waits until a task is finished before starting another one.

5. Multiple thread:-
A process with two threads of execution, running on a single
processor

6. Benefits
Responsiveness
Resource Sharing
Economy
Scalability

7. Responsiveness:-
Multithreading an interactive application may allow a program to
continue running even if it is blocked or is performing a lengthy
operating, increasing responsiveness to the user.
Resource Sharing-
Thread share resource of process, easier than shared memory or
message passing.

8. Economy:- cheaper than process creation, thread switching lower
overhead than context switching.
Scalability:- process can take advantage of multiprocessor. The
multithreading can be greatly increased in a multiprocessor
architecture.

9. User Threads and kernel thread
User Level Threads -- User managed threads
Kernel Level Threads -- Operating System managed threads acting on
kernel, an operating system core.

10. User Level Threads:-
In this case, application manages thread management kernel is not
aware of the existence of threads.
The thread library contains code for creating and destroying threads, for
passing message and data between threads, for scheduling thread
execution

11. Kernel Level Threads:-
Thread management done by the Kernel.
There is no thread management code in the application area.
 Kernel threads are supported directly by the operating system.
Any application can be programmed to be multithreaded.

12. Multithreading Models
Some operating system provide a combined user level
thread and Kernel level thread facility. Solaris is a good
example of this combined approach.

13. Multithreading models are three types
Many to many relationship.
Many to one relationship.
One to one relationship.

14. Many to Many Model

15. Many to One Model

16. One to One Model

17. Difference between User Level &
Kernel Level Thread
• User Level Threads
• User level threads are
faster to create and
manage.
• Implementation is by
a thread library at the
user level.
• Kernel Level Thread
• Kernel level threads
are slower to create
and manage.
• Operating system
supports creation of
Kernel threads.

18. • User level thread is
generic and can run
on any operating
system.
• Multi-threaded
application cannot
take advantage of
multiprocessing.
• Kernel level thread is
specific to the
operating system.
• Kernel routines
themselves can be
multithreaded.