PPT: Threads

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T h r e a d s
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T h r e a d s
What is a Thread?
Thread Definition
A thread is a path of execution within 
a process. A single process can 
contain multiple threads running 
concurrently.
Process vs Thread
The primary difference is that 
threads within the same process run 
in a shared memory space, while 
processes run in separate memory 
spaces.
Threads share their code section, 
data section, and OS resources (like 
open files and signals) with other 
threads in the same process.
Thread Components
Like a process, each thread has its 
own program counter (PC), register 
set, and stack space, allowing 
independent execution.
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T h r e a d s
What is a Thread?
Thread Definition
A thread is a path of execution within 
a process. A single process can 
contain multiple threads running 
concurrently.
Process vs Thread
The primary difference is that 
threads within the same process run 
in a shared memory space, while 
processes run in separate memory 
spaces.
Threads share their code section, 
data section, and OS resources (like 
open files and signals) with other 
threads in the same process.
Thread Components
Like a process, each thread has its 
own program counter (PC), register 
set, and stack space, allowing 
independent execution.
Advantages of Threads 
over Processes
Responsiveness
If a process is divided into 
multiple threads, output from 
completed threads can be 
immediately returned, improving 
application responsiveness.
Faster Context 
Switch
Context switch time between 
threads is lower compared to 
process context switching, which 
requires more CPU overhead.
Effective 
Multiprocessor 
Utilization
Multiple threads within a single 
process can be scheduled across 
multiple processors, making 
execution faster.
Resource Sharing & 
Communication
Resources like code, data, and 
files can be shared among all 
threads within a process. 
Communication between threads 
is easier due to shared address 
space.
Page 4


T h r e a d s
What is a Thread?
Thread Definition
A thread is a path of execution within 
a process. A single process can 
contain multiple threads running 
concurrently.
Process vs Thread
The primary difference is that 
threads within the same process run 
in a shared memory space, while 
processes run in separate memory 
spaces.
Threads share their code section, 
data section, and OS resources (like 
open files and signals) with other 
threads in the same process.
Thread Components
Like a process, each thread has its 
own program counter (PC), register 
set, and stack space, allowing 
independent execution.
Advantages of Threads 
over Processes
Responsiveness
If a process is divided into 
multiple threads, output from 
completed threads can be 
immediately returned, improving 
application responsiveness.
Faster Context 
Switch
Context switch time between 
threads is lower compared to 
process context switching, which 
requires more CPU overhead.
Effective 
Multiprocessor 
Utilization
Multiple threads within a single 
process can be scheduled across 
multiple processors, making 
execution faster.
Resource Sharing & 
Communication
Resources like code, data, and 
files can be shared among all 
threads within a process. 
Communication between threads 
is easier due to shared address 
space.
Thread Characteristics
Sequential 
Execution with 
Parallel Illusion
Threads are executed one after 
another but give the illusion of 
parallel execution through rapid 
context switching.
Thread 
Components
Program counter
Register set
Stack space
Interdependence
Threads are not independent of 
each other as they share code, 
data, and OS resources within the 
same process.
State Changes
Each thread has different states 
(running, ready, blocked) that it 
transitions between during 
execution.
Page 5


T h r e a d s
What is a Thread?
Thread Definition
A thread is a path of execution within 
a process. A single process can 
contain multiple threads running 
concurrently.
Process vs Thread
The primary difference is that 
threads within the same process run 
in a shared memory space, while 
processes run in separate memory 
spaces.
Threads share their code section, 
data section, and OS resources (like 
open files and signals) with other 
threads in the same process.
Thread Components
Like a process, each thread has its 
own program counter (PC), register 
set, and stack space, allowing 
independent execution.
Advantages of Threads 
over Processes
Responsiveness
If a process is divided into 
multiple threads, output from 
completed threads can be 
immediately returned, improving 
application responsiveness.
Faster Context 
Switch
Context switch time between 
threads is lower compared to 
process context switching, which 
requires more CPU overhead.
Effective 
Multiprocessor 
Utilization
Multiple threads within a single 
process can be scheduled across 
multiple processors, making 
execution faster.
Resource Sharing & 
Communication
Resources like code, data, and 
files can be shared among all 
threads within a process. 
Communication between threads 
is easier due to shared address 
space.
Thread Characteristics
Sequential 
Execution with 
Parallel Illusion
Threads are executed one after 
another but give the illusion of 
parallel execution through rapid 
context switching.
Thread 
Components
Program counter
Register set
Stack space
Interdependence
Threads are not independent of 
each other as they share code, 
data, and OS resources within the 
same process.
State Changes
Each thread has different states 
(running, ready, blocked) that it 
transitions between during 
execution.
Threads vs Processes: Similarities 
and Differences
Similarities
Only one thread or process 
is active at a time
Within a process, both 
execute sequentially
Both can create children
Differences
Threads are not 
independent, processes are
Threads are designed to 
assist each other
Processes may or may not 
assist each other
Resource 
Management
Processes have separate 
memory spaces
Threads share memory 
within a process
Threads have individual 
stacks and registers