This document discusses process synchronization techniques. It describes the critical section problem where multiple processes need synchronized access to shared resources. Solutions discussed include semaphores, which use wait and signal operations to control access to shared variables. The document also discusses problems that can arise like deadlocks when processes wait indefinitely for resources held by other blocked processes, and starvation where a process is denied access for an extended time.
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
For Complete Learning: http://www.thelearnet.com/
Background
The Critical-Section Problem
Synchronization Hardware
Semaphores
Classical Problems of Synchronization
Critical Regions
Monitors
Synchronization in Solaris 2 & Windows 2000
Producer Consumer Problem in C explained.pptossama8
Producer-Consumer problem is a classical synchronization problem in the operating system. With the presence of more than one process and limited resources in the system the synchronization problem arises. If one resource is shared between more than one process at the same time then it can lead to data inconsistency.
This document covers important concepts of process synchronization like: Background, critical section problem, critical region, synchronization hardware, semaphores. It is beneficial for engineering students of aryabhatta knowledge university of bihar (A.K.U. Bihar).
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
For Complete Learning: http://www.thelearnet.com/
Background
The Critical-Section Problem
Synchronization Hardware
Semaphores
Classical Problems of Synchronization
Critical Regions
Monitors
Synchronization in Solaris 2 & Windows 2000
Producer Consumer Problem in C explained.pptossama8
Producer-Consumer problem is a classical synchronization problem in the operating system. With the presence of more than one process and limited resources in the system the synchronization problem arises. If one resource is shared between more than one process at the same time then it can lead to data inconsistency.
This document covers important concepts of process synchronization like: Background, critical section problem, critical region, synchronization hardware, semaphores. It is beneficial for engineering students of aryabhatta knowledge university of bihar (A.K.U. Bihar).
GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
Guy Korland, CEO and Co-founder of FalkorDB, will review two articles on the integration of language models with knowledge graphs.
1. Unifying Large Language Models and Knowledge Graphs: A Roadmap.
https://arxiv.org/abs/2306.08302
2. Microsoft Research's GraphRAG paper and a review paper on various uses of knowledge graphs:
https://www.microsoft.com/en-us/research/blog/graphrag-unlocking-llm-discovery-on-narrative-private-data/
Encryption in Microsoft 365 - ExpertsLive Netherlands 2024Albert Hoitingh
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LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...DanBrown980551
Do you want to learn how to model and simulate an electrical network from scratch in under an hour?
Then welcome to this PowSyBl workshop, hosted by Rte, the French Transmission System Operator (TSO)!
During the webinar, you will discover the PowSyBl ecosystem as well as handle and study an electrical network through an interactive Python notebook.
PowSyBl is an open source project hosted by LF Energy, which offers a comprehensive set of features for electrical grid modelling and simulation. Among other advanced features, PowSyBl provides:
- A fully editable and extendable library for grid component modelling;
- Visualization tools to display your network;
- Grid simulation tools, such as power flows, security analyses (with or without remedial actions) and sensitivity analyses;
The framework is mostly written in Java, with a Python binding so that Python developers can access PowSyBl functionalities as well.
What you will learn during the webinar:
- For beginners: discover PowSyBl's functionalities through a quick general presentation and the notebook, without needing any expert coding skills;
- For advanced developers: master the skills to efficiently apply PowSyBl functionalities to your real-world scenarios.
Essentials of Automations: Optimizing FME Workflows with ParametersSafe Software
Are you looking to streamline your workflows and boost your projects’ efficiency? Do you find yourself searching for ways to add flexibility and control over your FME workflows? If so, you’re in the right place.
Join us for an insightful dive into the world of FME parameters, a critical element in optimizing workflow efficiency. This webinar marks the beginning of our three-part “Essentials of Automation” series. This first webinar is designed to equip you with the knowledge and skills to utilize parameters effectively: enhancing the flexibility, maintainability, and user control of your FME projects.
Here’s what you’ll gain:
- Essentials of FME Parameters: Understand the pivotal role of parameters, including Reader/Writer, Transformer, User, and FME Flow categories. Discover how they are the key to unlocking automation and optimization within your workflows.
- Practical Applications in FME Form: Delve into key user parameter types including choice, connections, and file URLs. Allow users to control how a workflow runs, making your workflows more reusable. Learn to import values and deliver the best user experience for your workflows while enhancing accuracy.
- Optimization Strategies in FME Flow: Explore the creation and strategic deployment of parameters in FME Flow, including the use of deployment and geometry parameters, to maximize workflow efficiency.
- Pro Tips for Success: Gain insights on parameterizing connections and leveraging new features like Conditional Visibility for clarity and simplicity.
We’ll wrap up with a glimpse into future webinars, followed by a Q&A session to address your specific questions surrounding this topic.
Don’t miss this opportunity to elevate your FME expertise and drive your projects to new heights of efficiency.
A tale of scale & speed: How the US Navy is enabling software delivery from l...sonjaschweigert1
Rapid and secure feature delivery is a goal across every application team and every branch of the DoD. The Navy’s DevSecOps platform, Party Barge, has achieved:
- Reduction in onboarding time from 5 weeks to 1 day
- Improved developer experience and productivity through actionable findings and reduction of false positives
- Maintenance of superior security standards and inherent policy enforcement with Authorization to Operate (ATO)
Development teams can ship efficiently and ensure applications are cyber ready for Navy Authorizing Officials (AOs). In this webinar, Sigma Defense and Anchore will give attendees a look behind the scenes and demo secure pipeline automation and security artifacts that speed up application ATO and time to production.
We will cover:
- How to remove silos in DevSecOps
- How to build efficient development pipeline roles and component templates
- How to deliver security artifacts that matter for ATO’s (SBOMs, vulnerability reports, and policy evidence)
- How to streamline operations with automated policy checks on container images
PHP Frameworks: I want to break free (IPC Berlin 2024)Ralf Eggert
In this presentation, we examine the challenges and limitations of relying too heavily on PHP frameworks in web development. We discuss the history of PHP and its frameworks to understand how this dependence has evolved. The focus will be on providing concrete tips and strategies to reduce reliance on these frameworks, based on real-world examples and practical considerations. The goal is to equip developers with the skills and knowledge to create more flexible and future-proof web applications. We'll explore the importance of maintaining autonomy in a rapidly changing tech landscape and how to make informed decisions in PHP development.
This talk is aimed at encouraging a more independent approach to using PHP frameworks, moving towards a more flexible and future-proof approach to PHP development.
Builder.ai Founder Sachin Dev Duggal's Strategic Approach to Create an Innova...Ramesh Iyer
In today's fast-changing business world, Companies that adapt and embrace new ideas often need help to keep up with the competition. However, fostering a culture of innovation takes much work. It takes vision, leadership and willingness to take risks in the right proportion. Sachin Dev Duggal, co-founder of Builder.ai, has perfected the art of this balance, creating a company culture where creativity and growth are nurtured at each stage.
Generative AI Deep Dive: Advancing from Proof of Concept to ProductionAggregage
Join Maher Hanafi, VP of Engineering at Betterworks, in this new session where he'll share a practical framework to transform Gen AI prototypes into impactful products! He'll delve into the complexities of data collection and management, model selection and optimization, and ensuring security, scalability, and responsible use.
Transcript: Selling digital books in 2024: Insights from industry leaders - T...BookNet Canada
The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
Link to video recording: https://bnctechforum.ca/sessions/selling-digital-books-in-2024-insights-from-industry-leaders/
Presented by BookNet Canada on May 28, 2024, with support from the Department of Canadian Heritage.
UiPath Test Automation using UiPath Test Suite series, part 3DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 3. In this session, we will cover desktop automation along with UI automation.
Topics covered:
UI automation Introduction,
UI automation Sample
Desktop automation flow
Pradeep Chinnala, Senior Consultant Automation Developer @WonderBotz and UiPath MVP
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
2. Background
Concurrent access to shared data may result in data
inconsistency.
Maintaining data consistency requires mechanisms to
ensure the orderly execution of cooperating processes.
Shared-memory solution to bounded-buffer problem
allows at most n – 1 items in buffer at the same time. A
solution, where all N items are used is not simple.
Suppose that we modify the producer-consumer code by adding a
variable counter, initialized to 0 and incremented each time a new
item is added to the buffer
3. Bounded-Buffer
Shared data
#define BUFFER_SIZE 10
typedef struct {
. . .
} item;
item buffer[BUFFER_SIZE];
int in = 0;
int out = 0;
int counter = 0;
4. Bounded-Buffer
Producer process
item nextProduced;
while (1) {
while (counter == BUFFER_SIZE)
; /* do nothing */
buffer[in] = nextProduced;
in = (in + 1) % BUFFER_SIZE;
counter++;
}
5. Bounded-Buffer
Consumer process
item nextConsumed;
while (1) {
while (counter == 0)
; /* do nothing */
nextConsumed = buffer[out];
out = (out + 1) % BUFFER_SIZE;
counter--;
}
6. Bounded Buffer
The statements
counter++;
counter--;
must be performed atomically.
Atomic operation means an operation that completes entirety without
interruption.
7. Bounded Buffer
Assume counter is initially 5. One interleaving of
statements is:
T0: producer: register1 = counter (register1 = 5)
T1: producer: register1 = register1 + 1 (register1 = 6)
T2: consumer: register2 = counter (register2 = 5)
T3: consumer: register2 = register2 – 1 (register2 = 4)
T4: producer: counter = register1 (counter = 6)
T5: consumer: counter = register2 (counter = 4)
The value of count may be either 4 or 6, where the
correct result should be 5.
8. Race Condition
Race condition: The situation where several processes access –
and manipulate shared data concurrently. The final value of the
shared data depends upon which process finishes last.
To prevent race conditions, concurrent processes must be
synchronized.
9. The Critical-Section Problem
n processes all competing to use some shared data.
Each process has a segment of code, called critical section, in which
the shared data is accessed.
Problem – ensure that when one process is executing in its critical
section, no other process is allowed to execute in its critical section.
Each process must request permission to enter in its critical section:
- the section of code implementing this request is entry section.
- the critical section may be followed by exit section.
- the remaining code is the remainder section.
10. Solution to Critical-Section Problem
1. Mutual Exclusion: If process Pi is executing in its critical section, then
no other processes can be executing in their critical sections.
2. Progress:
- If no process is executing in its critical section.
- There exist some processes that wish to enter their critical section.
- Then only those processes that are not executing in the remainder
section can participate in the decision which of the processes that will
enter next.
- Thus the selection can not be postponed indefinitely.
3. 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.
11. Bakery Algorithm
Before entering its critical section, process receives a number.
Holder of the smallest number enters the critical section.
The numbering scheme always generates numbers in increasing
order of enumeration; i.e., 1,2,3,3,3,3,4,5...
Critical section for n processes
12. Bakery Algorithm
do {
choosing[i] = true;
number[i] = max(number[0], number[1], …, number [n – 1])+1;
choosing[i] = false;
for (j = 0; j < n; j++) {
while (choosing[j]) ;
while ((number[j] != 0) && (number[j,j] < number[i,i])) ;
}
critical section
number[i] = 0;
remainder section
} while (1);
13. Silberschatz, Galvin and Gagne 2002
7.13
Semaphores
Synchronization tool
Semaphore S – integer variable
can only be accessed via two indivisible (atomic)
operations
wait (S):
while S 0 do no-op;
S--;
signal (S):
S++;
14. Silberschatz, Galvin and Gagne 2002
7.14
Critical Section of n Processes
Process Pi:
do {
wait(mutex);
critical section
signal(mutex);
remainder section
} while (1);
15. Silberschatz, Galvin and Gagne 2002
7.15
Semaphore Implementation
Define a semaphore as a structure
typedef struct {
int value;
struct process *L;
} semaphore;
Assume two simple operations:
block suspends the process that invokes it.
wakeup(P) resumes the execution of a blocked process P.
16. Silberschatz, Galvin and Gagne 2002
7.16
Implementation
Semaphore operations now defined as
wait(S):
S.value--;
if (S.value < 0) {
add this process to S.L;
block;
}
signal(S):
S.value++;
if (S.value <= 0) {
remove a process P from S.L;
wakeup(P);
}
17. Silberschatz, Galvin and Gagne 2002
7.17
Semaphore as a General Synchronization Tool
Execute B in Pj only after A executed in Pi
Use semaphore flag initialized to 0
Code:
Pi Pj
A wait(flag)
signal(flag) B
18. Silberschatz, Galvin and Gagne 2002
7.18
Deadlock and Starvation
Deadlock – two or more processes are waiting indefinitely for
an event that can be caused by only one of the waiting
processes.
Let S and Q be two semaphores initialized to 1
P0 P1
wait(S); wait(Q);
wait(Q); wait(S);
signal(S); signal(Q);
signal(Q) signal(S);
Starvation – indefinite blocking. A process may never be
removed from the semaphore queue in which it is suspended.