Introduction to Threads in Operating Systems
Operating Systems
(CS 340 D)
Princess Nora University
Faculty of Computer & Information Systems
Computer science Department
(Chapter-4)
Threads
Chapter 4: Threads
1.
Motivation
2.
Benefits
3
OBJECTIVES
:
To introduce the
notion of a thread
—
a fundamental unit of CPU utilization that forms the basis of
multithreaded computer systems.
4
OVERVIEW
A
thread
:
is a basic unit of CPU utilization
(i.e. It
is the
smallest
sequence of programmed instructions that
can be managed
independently)
Threads provide a way
to improve application
performance
through parallelism.
5
Thread comprises
:
It
shares
with other threads
belonging to the
same process
its :
code section,
data section
other operating system resources
.
OVERVIEW (cont..)
6
A
traditional
(or
heavyweight
) process has a
single
thread of
control.
A thread could be considered a ‘
lightweight
’ process If a process
has
multiple threads
of control, it can
perform more than one
task at a time.
Each
thread belongs to exactly
one
process and no thread can
exist outside a process.
OVERVIEW (cont..)
7
Single and Multithreaded Processes
n
Traditional ( heavyweight ) process
has
a single thread of control - There is
one
program counter, and
one
sequence of
instructions that can be carried out at any
given time.
n
Multi-threaded applications
have multiple
threads within a single process - Every thread
have their own
program counter, stack
and set of registers,
but
sharing
common
code, data, and certain structures such as
open files.
8
MOTIVATION
Many software packages that run on modern desktop PCs are
multithreaded.
An application typically is implemented as
a separate process
with
several threads
of control.
E.G. (1)
:
A word processor
may have :
o
a thread for displaying graphics,
o
a thread for responding to keystrokes from the user,
o
a third thread for spelling and grammar checking
9
MOTIVATION
E.G. (2) :
A web server
–
Multiple threads allow for
multiple requests
to be satisfied
simultaneously,
without having to service requests sequentially or to
fork off (/create) separate processes for every incoming
request….(creating a new thread belongs to an existing process is
less
overhead
of creating a new process)
Most operating system kernels are now multithreaded
several threads operate in the kernel, and each thread performs a specific task, such
as managing devices or interrupt handling.
10
BENEFITS
There are four major
categories
of benefits to multi-
threading:
1- Responsiveness
-
One thread may provide
rapid response
while other threads are blocked or slowed down doing intensive
calculations.
2- Economy
-
Creating and managing threads is
much faster
than performing the same tasks for processes.
11
BENEFITS (cont..)
There are four major
categories
of benefits to multi-
threading:
3-Resource sharing
–
Processes may only share resources through techniques (e.g.
shared memory or message passing) …Such techniques
must
be explicitly
arranged by the programmer.
By default
threads share common code, data, and other
resources, which allows multiple tasks to be performed
simultaneously in
a
single address space.
12
4- Scalability
The benefits of multithreading can be greatly increased in a
multiprocessor architecture, where
threads may be running
in parallel
on different processors.
A
single-threaded process
can only run on one
processor, regardless how many CPUs are available.
Note that single threaded processes can still benefit from multi-
processor architectures when there are multiple processes
contending for the CPU
BENEFITS (cont..)
13
Thank you
End of
Chapter 4
14
This content delves into the concept of threads in operating systems, highlighting their role as fundamental units of CPU utilization. Threads enhance application performance through parallelism, sharing resources within a process and enabling multitasking capabilities. The discussion covers the structure of threads, distinguishing between traditional heavyweight processes and modern multithreaded applications. Additionally, it elaborates on the motivation behind utilizing threads in software development, emphasizing the prevalence of multithreaded applications in modern computing environments.
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Presentation Transcript
Princess Nora University Faculty of Computer & Information Systems Computer science Department Operating Systems (CS 340 D)
(Chapter-4) Threads
Chapter 4: Threads 1. Motivation 2. Benefits 3
OBJECTIVES: To introduce the notion of a thread a fundamental unit of CPU utilization that forms the basis of multithreaded computer systems. 4
OVERVIEW A thread: is a basic unit of CPU utilization (i.e. Itis the smallest sequence of programmed instructions that can be managed independently) Threads provide a way to improve application performance through parallelism. 5
OVERVIEW (cont..) Thread comprises : ID program counter register set stack It shares with other threads belonging to the same process its : code section, data section other operating system resources. 6
OVERVIEW (cont..) A traditional (or heavyweight) process has a single thread of control. A thread could be considered a lightweight process If a process has multiple threads of control, it can perform more than one task at a time. Each thread belongs to exactly one process and no thread can exist outside a process. 7
Single and Multithreaded Processes Traditional ( heavyweight ) process has a single thread of control - There is one program counter, and one sequence of instructions that can be carried out at any given time. Multi-threaded applications have multiple threads within a single process - Every thread have their own program counter, stack and set of registers, but sharing common code, data, and certain structures such as open files. 8
MOTIVATION Many software packages that run on modern desktop PCs are multithreaded. An application typically is implemented as a separate process with several threads of control. E.G. (1) : A word processor may have : o a thread for displaying graphics, o a thread for responding to keystrokes from the user, o a third thread for spelling and grammar checking 9
MOTIVATION E.G. (2) : A web server Multiple threads allow for multiple requests to be satisfied simultaneously, without having to service requests sequentially or to fork off (/create) separate processes for every incoming request .(creating a new thread belongs to an existing process is less overhead of creating a new process) Most operating system kernels are now multithreaded several threads operate in the kernel, and each thread performs a specific task, such as managing devices or interrupt handling. 10
BENEFITS There are four major categories of benefits to multi- threading: 1- Responsiveness - One thread may provide rapid response while other threads are blocked or slowed down doing intensive calculations. 2- Economy - Creating and managing threads is much faster than performing the same tasks for processes. 11
BENEFITS (cont..) There are four major categories of benefits to multi- threading: 3-Resource sharing Processes may only share resources through techniques (e.g. shared memory or message passing) Such techniques must be explicitly arranged by the programmer. By default threads share common code, data, and other resources, which allows multiple tasks to be performed simultaneously in a single address space. 12
BENEFITS (cont..) 4- Scalability The benefits of multithreading can be greatly increased in a multiprocessor architecture, where threads may be running in parallel on different processors. A single-threaded process can only run on one processor, regardless how many CPUs are available. Note that single threaded processes can still benefit from multi- processor architectures when there are multiple processes contending for the CPU 13
Thank you End of Chapter 4 14
