The critical section problem refers to ensuring that at most one process can execute its critical section, a code segment that accesses shared resources, at any given time. There are three requirements for a correct solution: mutual exclusion, meaning no two processes can be in their critical section simultaneously; progress, ensuring a process can enter its critical section if it wants; and bounded waiting, placing a limit on how long a process may wait to enter the critical section. Early attempts to solve this using flags or a turn variable were incorrect as they did not guarantee all three requirements.
Overview - Functions of an Operating System – Design Approaches – Types of Advanced
Operating System - Synchronization Mechanisms – Concept of a Process, Concurrent
Processes – The Critical Section Problem, Other Synchronization Problems – Language
Mechanisms for Synchronization – Axiomatic Verification of Parallel Programs - Process
Deadlocks - Preliminaries – Models of Deadlocks, Resources, System State – Necessary and
Sufficient conditions for a Deadlock – Systems with Single-Unit Requests, Consumable
Resources, Reusable Resources.
A brief introduction to Process synchronization in Operating Systems with classical examples and solutions using semaphores. A good starting tutorial for beginners.
In this presentation, I am explaining about Threads, types of threads, its advantages and disadvantages, difference between Process and Threads, multithreading and its type.
"Like the ppt if you liked the ppt"
LinkedIn - https://in.linkedin.com/in/prakharmaurya
Gives an overview about Process, PCB, Process States, Process Operations, Scheduling, Schedulers, Interprocess communication, shared memory and message passing systems
This is the twelfth set of slightly updated slides from a Perl programming course that I held some years ago.
I want to share it with everyone looking for intransitive Perl-knowledge.
A table of content for all presentations can be found at i-can.eu.
The source code for the examples and the presentations in ODP format are on https://github.com/kberov/PerlProgrammingCourse
Overview - Functions of an Operating System – Design Approaches – Types of Advanced
Operating System - Synchronization Mechanisms – Concept of a Process, Concurrent
Processes – The Critical Section Problem, Other Synchronization Problems – Language
Mechanisms for Synchronization – Axiomatic Verification of Parallel Programs - Process
Deadlocks - Preliminaries – Models of Deadlocks, Resources, System State – Necessary and
Sufficient conditions for a Deadlock – Systems with Single-Unit Requests, Consumable
Resources, Reusable Resources.
A brief introduction to Process synchronization in Operating Systems with classical examples and solutions using semaphores. A good starting tutorial for beginners.
In this presentation, I am explaining about Threads, types of threads, its advantages and disadvantages, difference between Process and Threads, multithreading and its type.
"Like the ppt if you liked the ppt"
LinkedIn - https://in.linkedin.com/in/prakharmaurya
Gives an overview about Process, PCB, Process States, Process Operations, Scheduling, Schedulers, Interprocess communication, shared memory and message passing systems
This is the twelfth set of slightly updated slides from a Perl programming course that I held some years ago.
I want to share it with everyone looking for intransitive Perl-knowledge.
A table of content for all presentations can be found at i-can.eu.
The source code for the examples and the presentations in ODP format are on https://github.com/kberov/PerlProgrammingCourse
An introduction to the OpenMP parallel programming model.
From the Scalable Computing Support Center at Duke University (http://wiki.duke.edu/display/scsc)
Operator Overloading and Scope of VariableMOHIT DADU
This slide is completely based on the Operator Overloading and the Scope of Variable. The example given to explain are based on C/C++ programming language.
Operating system 23 process synchronizationVaibhav Khanna
Processes can execute concurrently
May be interrupted at any time, partially completing execution
Concurrent access to shared data may result in data inconsistency
Maintaining data consistency requires mechanisms to ensure the orderly execution of cooperating processes
Illustration of the problem:Suppose that we wanted to provide a solution to the consumer-producer problem that fills all the buffers. We can do so by having an integer counter that keeps track of the number of full buffers. Initially, counter is set to 0. It is incremented by the producer after it produces a new buffer and is decremented by the consumer after it consumes a buffer
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
NO1 Uk best vashikaran specialist in delhi vashikaran baba near me online vas...Amil Baba Dawood bangali
Contact with Dawood Bhai Just call on +92322-6382012 and we'll help you. We'll solve all your problems within 12 to 24 hours and with 101% guarantee and with astrology systematic. If you want to take any personal or professional advice then also you can call us on +92322-6382012 , ONLINE LOVE PROBLEM & Other all types of Daily Life Problem's.Then CALL or WHATSAPP us on +92322-6382012 and Get all these problems solutions here by Amil Baba DAWOOD BANGALI
#vashikaranspecialist #astrologer #palmistry #amliyaat #taweez #manpasandshadi #horoscope #spiritual #lovelife #lovespell #marriagespell#aamilbabainpakistan #amilbabainkarachi #powerfullblackmagicspell #kalajadumantarspecialist #realamilbaba #AmilbabainPakistan #astrologerincanada #astrologerindubai #lovespellsmaster #kalajaduspecialist #lovespellsthatwork #aamilbabainlahore#blackmagicformarriage #aamilbaba #kalajadu #kalailam #taweez #wazifaexpert #jadumantar #vashikaranspecialist #astrologer #palmistry #amliyaat #taweez #manpasandshadi #horoscope #spiritual #lovelife #lovespell #marriagespell#aamilbabainpakistan #amilbabainkarachi #powerfullblackmagicspell #kalajadumantarspecialist #realamilbaba #AmilbabainPakistan #astrologerincanada #astrologerindubai #lovespellsmaster #kalajaduspecialist #lovespellsthatwork #aamilbabainlahore #blackmagicforlove #blackmagicformarriage #aamilbaba #kalajadu #kalailam #taweez #wazifaexpert #jadumantar #vashikaranspecialist #astrologer #palmistry #amliyaat #taweez #manpasandshadi #horoscope #spiritual #lovelife #lovespell #marriagespell#aamilbabainpakistan #amilbabainkarachi #powerfullblackmagicspell #kalajadumantarspecialist #realamilbaba #AmilbabainPakistan #astrologerincanada #astrologerindubai #lovespellsmaster #kalajaduspecialist #lovespellsthatwork #aamilbabainlahore #Amilbabainuk #amilbabainspain #amilbabaindubai #Amilbabainnorway #amilbabainkrachi #amilbabainlahore #amilbabaingujranwalan #amilbabainislamabad
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
2. The Critical-Section
A code segment that accesses shared variables (or other shared resources)
and that has to be executed as an atomic action is referred to as a critical
section.
n processes competing to use some shared data.
No assumptions may be made about speeds or the number of CPUs.
Each process has a code segment, called Critical Section (CS), in which
the shared data is accessed.
Problem – ensure that when one process is executing in its CS, no other
process is allowed to execute in its CS.
3. informally,
a critical section is a code segment that accesses shared variables and
has to be executed as an atomic action.
The critical section problem refers to the problem of how to ensure that
at most one process is executing its critical section at a given time.
Important: critical sections in different threads are not necessarily the
same code segment!
PROBLEM DESCRIPTION
4. PROBLEM DESCRIPTION
Formally,
Mutual exclusion: when a thread is executing in its critical section, no other
threads can be executing in their critical sections.
Progress: if no thread is executing in its critical section, and if there are
some threads that wish to enter their critical sections, then one of these threads
will get into the critical section.
Bounded waiting: after a thread makes a request to enter its critical section,
there is a bound on the number of times that other threads are allowed to enter
their critical sections, before the request is granted.
5. CS Problem Dynamics (1)
When a process executes code that manipulates shared data (or
resource), we say that the process is in it’s Critical Section (for that
shared data).
The execution of critical sections must be mutually exclusive: at any
time, only one process is allowed to execute in its critical section
(even with multiple processors).
So each process must first request permission to enter its critical
section.
6. CS Problem Dynamics (2)
The section of code implementing this request is called the Entry Section (ES).
The critical section (CS) might be followed by a Leave/Exit Section (LS).
The remaining code is the Remainder Section (RS).
The critical section problem is to design a protocol that the processes can use so
that their action will not depend on the order in which their execution is
interleaved (possibly on many processors).
7. General structure of process
while (true)
{
Entry-Section
Critical section
// contains accesses to shared variables or other resources.
Exit-Section
Non-critical section
// a thread may terminate its execution in this section.
}
8. EXPLANATION
ENTRY SECTION:- The process will request to enter the critical section
then a part of code decide wheather process can enter in the Critical
Section on not.
CRITICAL SECTION:- A code segment that accesses shared resources and
that has to be executed as an atomic action.
EXIT SECTION:- Locking section can be undone which is done in Critical
Section.
REMAINDER SECTION:- Remaining part of the program .
9. Solution to Critical-Section Problem
There are 3 requirements that must stand for a correct solution:
1. Mutual Exclusion
2. Progress
3. Bounded Waiting
We can check on all three requirements in each proposed solution,
even though the non-existence of each one of them is enough for an
incorrect solution.
10. Solution to CS Problem – Mutual Exclusion
1. Mutual Exclusion –
If process Pi is executing in its critical section, then no other processes can be
executing in their critical sections.
Whenever one process is entered in the critical section then there is no other
process can enter in the critical section.
Only one process can be execute at a time.
That means access to the critical section must be mutually exclusive.
11. Critical sections better be focused and short.
Better not get into an infinite loop in there.
If a process somehow halts/waits in its critical section, it
must not interfere with other processes.
IMPLICATIONS:
12. Solution to CS Problem– Progress
2. Progress –
If no process is executing in its critical section and there exist some
processes that wish to enter their critical section, then the selection of
the process that will enter the critical section next cannot be
postponed indefinitely:
If only one process wants to enter, it should be able to.
If two or more want to enter, one of them should succeed.
13. Solution to CS Problem– Bounded Waiting
Bounded Waiting – A bound must exist on the number of times that
other processes are allowed to enter their critical sections after a
process has made a request to enter its critical section and before that
request is granted.
• Assume that each process executes at a non zero speed.
• No assumption concerning relative speed of the n processes.
14. Types of solutions to CS
problem
Software Solutions :– Algorithms who’s correctness does not rely
on any other assumptions.
Hardware Solutions :– Rely on some special machine instructions.
Operating System solutions :– Provide some functions and data
structures to the programmer through system /library calls.
Programming Language solutions :– Linguistic constructs
provided as part of a language.
15. Each process disables all interrupts just after entering in its critical
section and re-enable all interrupts just before leaving critical section.
With interrupts turned off the CPU could not be switched to other
process.
Hence, no other process will enter its critical and mutual exclusion
achieved.
Disabling Interrupts
(Hardware Solution)
16. Disabling interrupts is sometimes a useful technique within the kernel
of an operating system,
But it is not appropriate as a general mutual exclusion mechanism for
users process.
The reason is that it is unwise to give user process the power to turn
off interrupts.
Conclusion
17. • In this solution, we consider a single, shared, (lock) variable, initially 0.
• When a process wants to enter in its critical section, it first test the lock.
• If lock is 0, the process first sets it to 1 and then enters the critical section.
• If the lock is already 1, the process just waits until (lock) variable becomes
0.
• Thus, a 0 means that no process in its critical section, and 1 means hold
your horses - some process is in its critical section.
Lock Variable
(Software Solution)
18. Drawbacks of
software solutions
Software solutions are very delicate .
Processes that are requesting to enter their critical section
are busy waiting (consuming processor time needlessly).
If critical sections are long, it would be more efficient to block
processes that are waiting.
20. Threads T0 and T1 use variables flag[i] and flag[j] to indicate their intention to enter their
critical section. A thread will not enter its critical section if the other thread has already
signaled its intention to enter.
boolean flag[i]=false , flag[j]=false ;
Incorrect Solution 1
T1
while (true) {
while (flag[ i ]) { ; } (1)
flag[ j ] = true; (2)
critical section (3)
flag[ j ] = false; (4)
non-critical section (5)
}
T0
while (true) {
while (flag[ j ]) { ; } (1)
flag[ i ] = true; (2)
critical section (3)
flag[ i ] = false; (4)
non-critical section (5)
}
This solution does not guarantee mutual exclusion.
21. T0
WHILE (TRUE) {
WHILE (TURN != 0) { ; } (1)
CRITICAL SECTION (2)
TURN = 1; (3)
NON-CRITICAL SECTION (4)
}
Global variable turn is used to indicate which thread is allowed to enter its
critical section, i.e., the threads take turns entering their critical sections. The
initial value of turn can be 0 or 1.
int turn = 1;
Incorrect Solution 2
T1
while (true) {
while (turn != 1) { ; } (1)
critical section (2)
turn = 0; (3)
non-critical section (4)
}
Thread T0 cannot exit the loop in (1) since the value of turn is 1 and turn will never be
changed by T1.
22. T0
while (true) {
flag0= true; (1)
while ( flag1) { (2)
flag0= false; (3)
while( flag1) {;} (4)
flag0= true; (5)
}
critical section (6)
Flag0= false; (7)
non-critical section (8)
}
T1
while ( true ) {
flag1= true; (1)
while ( Flag0) { (2)
flag1= false; (3)
while( Flag0) {;} (4)
flag1= true; (5)
}
critical section (6)
flag1= false; (7)
non-critical section (8)
}
Incorrect Solution 3
When one thread finds that the other thread also intends to enter its critical section, it
sets its own flag to false and waits for the other thread to exit its critical section.
23. Thus, the mutual exclusion requirement is satisfied.
In this execution sequence,
T0 enters its critical section infinitely often and
T1 waits forever to enter its critical section.
Thus, this solution does not guarantee bounded waiting.
This solution ensures that when both Flag0 and Flag1 are true,
only one of T0 and T1 is allowed to enter its critical section.
24. Correct solution:
Correct solution is a combination of solutions (2) and (3). If both threads intend to enter their
critical sections, then turn is used to break the tie.
boolean Flag0 = false , Flag1= false;
int turn; // no initial value for turn is needed.
T0
while (true) {
Flag0= true; (1)
turn = 1; (2)
while ( Flag1&& (3)
Turn == 1) { ; }
critical section (4)
Flag0= false; (5)
non-critical section (6)
}
T1
while (true) {
Flag1= true; (1)
turn = 0; (2)
while ( Flag0&& (3)
Turn == 0) { ; }
critical section (4)
Flag1= false; (5)
non-critical section (6)
}