Uses of Internet

Internet

Internet is a global network of inter-connected computers, where one computer is connected to other computer or any computerized device in any portion of the world.

Internet uses various internet protocol technologies. The recent introduction of mobile internet have been equally successful.

Uses of Internet

The key to success of Internet is the information. The better the quality, the more usage of Internet operations.

Large volume of Information: Internet can be used to collect information from around the world.

This information could relate to education, medicine, literature, software, computers, business, entertainment, friendship, tourism, and leisure.

People can search for information by visiting the home page of various search engines such as Google, Yahoo, Bing, etc. and also one can go to any particular site with the domain name(name of website like www.knowledgefn.blogspot.com )

News and Journals: All the newspapers, magazines and journals of the world are available on the Internet.

After the introduction of broadband and advanced mobile telecommunication technologies such as 3G (third generation) and 4G (fourth generation), the speed of internet service has increased tremendously.

Before internet we unable to even know about our own village, the news of city, but now person can get the latest news about the whole world in just few seconds.

Electronic Mode of Communication: Internet has given the most exciting mode of communication to all. We can send an E-mail (Electronic Mailing System) to all the corners of the world.

Chatting: There are many chatting software that can be used to send and receive real-time messages over the internet. 

We can chat with our friend and relatives using any one of the chatting software.

Social Networking: People can connect with old friends on social networking sites. They can even chat with them when they are online.

Social networking sites also allow us to share pictures with others. We can share pictures with our loved ones, while we are on a vacation.

People are even concluding business deals over these social networking sites such as Facebook.

Online Banking (Net-Banking): The use of internet can also be seen in the field of banking transactions. Many banks such as HBL, UBL, Payza Bank, Payoneer Bank, etc.

These offers online banking facilities to its customers. They can transfer funds from one account to another using the net-banking facility.

E-commerce: Internet is also used for carrying out business operations and that set of operations is known as Electronic Commerce (E-commerce).

Draz.pk and many other sites are available in Pakistan. Amazon is the largest e-commerce company in India. The rival, Amazon, is giving stiff competition to amazon.

Mobile commerce: Mobile commerce (also M-Commerce) refers to the commercial transaction that takes place over the mobile internet.

Using the mobile internet technology, many companies have introduced mobile version of websites and mobile apps, to promote and sell their products.

Customers can simply browse several through the products and buy online through mobile internet.

Mobile wallet: Many companies offer the service of mobile wallet to its customers. 

Users must have a smart-phone and internet connection to use this service.

Users can pay an amount into their mobile wallet, which they can use to make online payment such as bill payments, recharges, etc.

Entertainment: Apart from a major source of knowledge and information, the utility of Internet in the field of entertainment cannot be undermined.

We can visit various video sites and watch movies and serials at our convenient time.

Technology of the Future: Internet is the technology of future. In the times to come, offices would be managed at distant places through Internet.

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Severe Heart Attacks

Heart attacks area unit serious heart disease that “attack” all of a fast. Did you recognize that hurting, discomfort, sweating and nausea are often a proof of a heart attack?

Now so these facet effects will even lead to an entire loss of awareness.

Heart attacks happen once the blood provide to a locality of the center is blockaded. This obstruction causes each death and injury of the tissue within the native space of the center.

Because of the method that the interruption will dissent in size, as will the region that's affected. massive or very little, heart attacks area unit serious and frequently serious.

Regarded as such they're a therapeutic crisis that wants fast thought from a crisis restorative service.

Keeping centered of attack indications and additionally an entire medicative history, blood tests and graph results area unit what form up the analysis for heart attacks.

In convalescence the foremost very important factor is re-establishing the stream of blood back to the region of the center that has been interrupted. this can be achieved through lysis and/or surgical operation.

Thrombolysis may be a strategy during which the natural process is softened within the passage enymatically.

Surgical operation is that the system during which a balloon is used to push open the artery.

Importance is about on checking for various complications, that might forestall a second attack.

Through this checking, work is finished to wipe out any danger which will exist, and diminish the possibilities of additional heart attacks.

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Wellness

Have you ever detected the old saying “body, soul and mind”? conjointly try and perceive edges of exercise.

What is Wellness?

Wellness is after you square measure in AN optimum well-being state. it's once your non secular, physical, mental, social, intellectual and environmental state square measure in complete harmony.

Statistics has shown USA, that several times individuals need to decide to a healthier way, however fail to try to to thus.

Why? maybe there square measure unreasonable set goals that square measure impossible.

Or maybe we have a tendency to lack self-discipline and character to try to to what we say we square measure saying we have a tendency to are planning to do.

It is important to acknowledge that sureness and determination square measure coupled along with your capability to try to to what you say you're planning to do.

In different words, your inner strength is up to the force of your word.

which means that, after you systematically keep your word and do what you say you're planning to do, you demonstrate to yourself and to others around you that you simply square measure trustworthy.

Per se, the a lot of you say one thing and it happens, the a lot of you trust yourself on the premise that every one that you simply say become a reality in reality.

for instance, however would you're feeling after you say you're planning to win one thing, as an example, to figure out three times on, however instead, do nothing? unhealthy right? i do know i'd to.

There is a proverb that goes “How you are doing something is that the means you are doing everything”.

If you're thinking that that it's tough to stay your word in one aspects of your life, possibly, this same angle can show up itself during a totally different a part of your life.

So, what's a resolution to decide to our word?

1-Focus and do the items that you simply say you're planning to do. Use your energy to accomplish your set up.

Accomplishment brings regarding accomplishment. nevertheless within the event that you simply keep setting yourself up for disappointment by that specialize in unfinished things, then accomplishment could be a fantasy for you.

2- create your word a regulation that has got to be followed. create a word of honour to try to to what you say you're planning to do.

Your statement have to be compelled to mean one thing to you since it implies one thing to others.

Think about the chance that someone aforesaid to you that they might contend with a significant matter for you and afterwards failed to do as they aforesaid.

Would you concentrate on this individual worth of your trust? Possibly not.

Take the case of previous warriors in prehistoric times. they might rather die than to interrupt their commitment.

Their word meant far more that the rest. you furthermore mght will grow to be a soul, a well-being soul (without the death stuff), by that specialize in living work and sustaining your promise.


3- Commit step by step and complete your mission. Watch what you target. First, create very little commitment, then, expand very very little by little on them.

As an example, you affirm that “every morning i'll assume for five minutes before breakfast.” By doing the morning reflection and finishing different totally different commitments you announced, implies that you're on the thanks to personage.

This can be effective. confine mind that, you decide to one thing after you announce it vocally or through writing.

Your word is placed out into the universe. can you maintain it? i do know you will!

Well-being is regarding balance, to be in step with yourself, and to be complete. If you wish genuinely consummated in life, you need to begin to trust yourself.

Thus keep your word. Educate yourself, in addition as others, that you simply are often trustworthy. set up realistic commitment and complete them. you may feel higher regarding yourself and you may accomplish your objectives during a matter of moments.

Yuri Elkaim is that the owner and author of Total welfare Consulting, a foremost welfare, and well-being organization giving to individuals original programs and innovations to attain their objectives of physical and mental prosperity.

he's a awfully acclaimed fitness coach, confirmed kinesiologist, and former professional jock.

Through fittingly approved activity and nourishment programs, additionally to the attention of the inner person, Yuri has helped a large range of individuals win their well-being and welfare objectives.

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How to Eat Healthy?

For many, making an attempt to eat healthy may be a plight, particularly if the muse of your whole alimentation is predicated on food.

Fortunately, it isn’t not possible to start out feeding healthy. It all depends on your perception and the way determined you're to vary things.

First, recognize that you just don't ought to alter drastically and provides up your food all directly, since it might be troublesome to create that amendment, as long as these low organic process worth foods ar a habit inherent in you.

Nevertheless, there's nothing to fret concerning, as there's a learning curve in everything that you just wish to attain.

That means, if you're willing, and if you equip yourself patiently, determination and enthusiasm, you may attain your goal!

Once you create that amendment and feel nice, I assure you that you just won’t wish to seem back.

Not solely can you get pleasure from it, however you may relish knowing that you just ar up your well-being doing therefore.

Did you recognize that food has no wholesome factors to boost your wellness? In different words: food doesn't contribute to your well-being.

Yes, it's going to style smart, however, trust what it will to your body on a protracted run… that's why you shouldn’t eat it.

Lucky for you, here ar some mere tricks you'll be able to follow that may assist you create that swish change:

1- Eat food morning, hour and night, for a few time. Eat it till you get tired of something of it. Once you notice that you just feel unwell, you may mechanically diminish its intake.

After that, you almost certainly won’t even wish to eat food any longer.

2- In the slightest degree times, keep a bottle of water with you. Sometimes, you'll suppose you're hungry, however in point of fact, most of the time, that feeling is attributable to the very fact that you just ar dehydrated and thirsty.

Therefore, try and keep a bottle of water with you so as to stay your body hydrous.
The first time is also troublesome.

But, remember, it's “mind over matter”. If you place your mind to that, you'll be able to mate .
Each time you oppose to eat food, you may become stronger.

Once a jiffy, you’ll get use to the routine. it'll then be easier for you to continue your strategy.

3- don't become terribly hungry. If you're starving, chances are high that that you just can expertise a high level of cravings.

So leading you to feeding almost something, all the same the results it's going to wear your health.
For that reason, you ought to keep a healthy snack. It may keep you from food temptations.


4- Cravings don't last for ever. it's superb however the brain works, and you’d be surprise to grasp that, after you yearn food, however set your mind on another issue, you won’t even bear in mind you were hungry.
All it takes is your effort and mind-set. you'll be able to do it!

5- Eat enough supermolecule, per you daily demand. supermolecule ar nutrients that may bolster your well-being. they're going to assist you feel full, if you eat the proper food that has supermolecule.

Some food that contain proteins are: eggs, nuts, meat, chicken, fish, cheese, beans, lentils and seeds.

I hope the following pointers can assist you step by step create that amendment from food to healthy feeding.

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Healthy food for Students

Today i need to speak to you regarding consumption of healthy food for college kids.

It is typically tough for college kids to eat healthy once they're off to school. this can be a complete new story.

It conjointly means that, late night dish, takeouts, deliveries, and even food from buggies.

Despite the actual fact that these nutriment style improbably delicious, it’s virtually bound that they're not helpful for a student’s health.

The food choice students create will have an impression on their performance in school, as well as, on their health.

For instance, poor food intake will have an effect on students to stay alert throughout category.

Furthermore, they will lack adequate nutrients and be in danger to develop glandular fever once it knocks on field.

For that reason, students ought to consume healthy food to nourish their body and mind.

The issue isn't solely regarding intense food, it's regarding lacking correct minerals, proteins, vitamins and carbohydrates that folks need so as to be healthy.

Vitamins and minerals square measure extraordinarily essential once it comes time to defensive the body against sicknesses.

This doesn't mean that students should run and store up the larder of vitamins and supplements.
Instead, it’s higher for college kids to get all their nourishment from healthy food.

You can get antioxidant in citrus fruits like: lime, grapefruits, orange, lemon.
Also get vitamin A once you drink milk and eat dairy farm merchandise.

And get tocopherol once you consume inexperienced bifoliate vegetables, nuts, and even food grain.
This is the most effective thanks to nourish your body.

Your body depends on these vitamins for numerous reasons.
Now, a suggestion, once you intake food on field, hop over sodas and choose 100% juice drinks instead.

Choose the healthy food offered like dish or recent vegetables, fruits or perhaps cereals.

You should invariably be aware that intense healthy isn’t on the subject of staying off from oily foods.

Consumption healthy entails obtaining a well-balanced diet.

As well as, obtaining the proper nutrients and vitamins your body desires. this might even assist you to be perform higher throughout your categories

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How to drive Traffic

Do you want to increase your website traffic and want to earn dollars? do you want to rank your website? do you want your website to search in google? if you want all these in free I will tell you 2 best ways to achieve all. 

By visiting others website you can earn traffic to your website there are few websites which provide you platform(software) that automatically visit other website and send traffic to your website. 

Everyone wants to increase website traffic as its directly connected to revenue. I am sharing some powerful tricks that you must use.

Otohits.net

It's the best platform which provides you all freeway you can reduce your bounce rate up to zero, you can send hits from any website like Google, Facebook, Linkedin etc.

It sends all the hits direct by HTTP by default. you win up to 50 Euros if you are the top points earner, there are other prices as well for 2nd, third. up to 10. 

You can be rewarded points as well.You can surf online and also can download the desktop application to earn traffic.

You can earn 10% points of your referral, there is no limit on referral even you will earn points on each referral as the reward by Otohits.net and much more,

 

HitLeap

It's the best platform which provides you all freeway you to earn traffic.you can not send hits from any website like Google, Facebook, Linkedin etc if you are a standard user if you upgrade you will be able to do so.

It sends all the hits direct by HTTP by default. You need to download the desktop application to earn traffic.

You can earn 10% Minutes of your referral, there is no limit on referral even HitLeap you will earn points on each referral as the reward  and much more,



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Hypertension And Heart

Today i would like to converse with you regarding high blood pressure and your heart.

Hypertension will negatively have an effect on our lives. what is more, it will devastate varied organs we've got in our body.

Its results for the center square measure particularly hurtful. high blood pressure and coronary illness square measure solidly connected.

Direct to high blood pressure primarily builds the burden on the left zone of the center. Subsequently, Arterioles square measure habitually drained or mounted, and expands protection from cardiovascular system.

At the purpose once this happens, the center has to work supplementary to thrust out blood into the vein framework Right once one muscle is manhandled, it's likely to extend in measure and mass. the center muscles react in an exceedingly similar manner.

A widened heart implies that burden. Heart swelling will be perceived in an exceedingly number of ways: 1-A chest x-beam will divulge regarding the condition 2-Also associate degree cardiogram 3-As well as a physical examination In varied patients United Nations agency endure of high blood pressure, the dividers of the left facet ventricle thicken.

This makes the center increment in work. At last, the center battles and therefore the left five hundredth of the center doesn't pump blood adequately to any extent further.

 At the purpose once this happens, the body's primary organs and tissues square measure denied satisfactory blood conveyance.

Thus, the influenced individual finally ends up exhausted and weak. Because of the upper power within the ventricle, blood from the lungs cannot consume into the simplest compartment of the center (the chamber).

During this manner, the tissues of the respiratory organ finish up engorged which expedites scenes of shortness of breath and hacks.

The drained individual might have a dry hack or maybe frothy liquid body substance that contain bloodstains.

This can be associate degree uncommonly surprising to the drained individual and therefore the people United Nations agency square measure observance.

In associate degree extreme assault, it seems to the drained person who he or she is breathless to death.

To be wanting breath thanks to heart problems is also initially discovered amid dependable physical exercise.

If the circumstance has propelled additional, shortness of breath might happen even whereas resting. What's additional, this can be a remarkable real condition and got to be controlled instantly.

If this gets most passing awful, the right portion of the center can likewise be influenced. precisely once compel creates within the correct chamber, it'll be onerous for veins to consume blood into it.

Right once the heart's condition rots to the current stage, the external jugular veins might get the chance to be magnified and can be all the additional standing out.

These veins will be seen near the skin and will be clear even in sound adults, but strain on the center will grow their swelling.

 There square measure some extraordinary signs of the right facet of the center breaking down.

They join: 1-An distended liver 2-Swollen lower legs and feet 3-Loss of craving 4-Lower pee stream and 5-Swollen abdomen Hypertension and coronary complaint ofttimes have a circumstances and finish results association.

Rolling out basic enhancements and alter in manner of life will fight each.

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Benefits of Exercise

Our bodies are astounding and, in the meantime, exceptionally mind boggling, accordingly making them difficult to comprehend, which can now and then abandon us careless in regards to our own needs.

There is simply so much that despite everything we disregard and, maybe, so much that we will never at any point know.

Exercise

In any case, I have constantly realized that physical exercise is a decent cure for some, disease's the body could experience or experience.

As I was growing up, I would invest days playing outside, getting natural air. I was an extremely dynamic kid!

That likewise implies that, amid that time, my body was discharging numerous endorphins, which are hormones, or chemicals, that speak with the cerebrum and diminish the impression of agony.

The point I am getting at, here, is that normal action, or exercise, could help lessen an ailment you may have, as well as could crush it.

You don't have to draw in into some extraordinary type of activity, simply take a stab at anything that can keep you fit as a fiddle.

Also, best of all, there is no compelling reason to join an exercise center, in the event that you can't, as it should all be possible from home!

weight loss

Simply recall that the general significance is to attempt and be fit as a fiddle, while remaining dynamic.

You can begin to take after a minor exercise schedule that will enable you to accomplish that. Additionally, you'll have to take after a nutritious eating routine that will fuel your body soundly.

 It is perfect to consolidate practices that will help your general body, heart, muscles, as well as your perseverance and adaptability.

Consequently, you should play out some cardio, weight, or your own body work out, a reiteration of sets and some extends.

Your Heart 

To help your hearth, cardio practice is the approach. This only intends to move and be dynamic at a quick pace.

For instance, you can do some hopping Jacks, keep running set up, substitute knee raises, squat, or do jumps.

Cardio is basic: it is an action that will influence your heart to pump and jump-start the system through veins.

Your Muscles 

To fabricate your muscles, you should perform weighted exercise. This should be possible with straightforward devices, for example, dumbbells, for instance.

On the off chance that you don't have any hardware, your muscles can even now be created utilizing the heaviness of your own body. Intriguing, would it say it isn't?

Perseverance 

To build your perseverance, you should rehash sets of activity, again and again!

Adaptability 

You should play out a few sorts of extends. This will help to loosing up any tight muscle, while helping you turn out to be more adaptable.

Have you at any point seen how great it feels to extend? Here and there the body does some peculiar sound all the while, yet it's all great!

Here Is a Simple Workout

Exercise Sets Repetition

Bouncing Jacks 2 15

Board 2 15 seconds

Knee Raises 2 15

Sit Ups 2 15

Straightforward Squats 2 20

Push Ups 2 15

Lurches 2 20

Arm circles 2 20 sec/each side

Basic extends 1 15 sec/each

I trust you will appreciate this exercise! I can guarantee you that your wellbeing will profit by it.

Afterward, when you feel good, you can take part in more propel exercise.

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Earning with YouTube Step by Step

One can earn by YouTube in just a few hours!! You can also become youtube partner to earn with YouTube. The initial step is to create the account, if you have Gmail id you can use it for signing purpose otherwise, you need to create a new Gmail Id by which you will be signed in on you Youtube.

 After signing you have click on your you have to left click on Icon that will appear in place of the sign in button, it shows you all the options, in which you have to click on My channel.

When You will click on my channel new page will appear, in which you have to write channel name, description, keyword etc.

When you are done with this you need to upload the videos, the video that you will upload must not be downloaded from any source of the internet if you uploaded such kind of content your account might be suspended because other people use copyright system to protect their videos. when you will upload your videos you also need to copyright your videos if you think your video will be copied.  

When you are done with this you need to promote your videos by the social links like Facebook, LikesBee, Twitter, Google+ etc to get visitors on your youtube channel, try to upload and update your videos so that visitors subscribe to your channel and keep continue to watching your videos.

Monetize your videos In order to start earning money on your videos, you’ll need to enable monetization. This means you are allowing YouTube to place ads in your video. This also means that you acknowledge that there is no copyrighted material in your video.

When you will enable monetization You need to signup for Google Adsense for this you must be 18 years old, and then you have provide valid data like Postal Address, PayPal or any Credit card number for your verification, mobile number verification and the payment method etc, After signup, Youtube will notify you by email your account has been approved or disapproved but in the case of youtube 99% accounts are approved, when your account will be approved you need to promote your videos. note you don't have to click any ad that is available in your videos. 2nd you also don't have to watch your own videos in both cases your account will be suspended.

After approval of Adsense, you have had upload videos frequently for engaging your audience, remember as your audience increase your earning also increases. Adsense will pay will pay you by your chosen method when your earning reaches to hundred dollars, youtube is paying once in a month if your earning is reached $100. if it is less than $100 then you have wait for the 2nd month, it does not matter your earning is greater than $100 after the payment date. you have to wait for next month to withdraw your money.

I hope my this article will help you to earn by youtube, keep me remember in your prayer's and stay blessed. in the case of any help, you can contact me by commenting on this post.

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Earning with Blog

A blog is a discussion or informational website published on the World Wide Web consisting of discrete, often informal posts. Posts are typically displayed in reverse chronological order, so that the most recent post appears first, at the top of the web page. The blog is usually working of a single individual, occasionally of a small group, and often covered a single subject or topic.

Many blogs provide commentary on a particular subject or topic, ranging from politics to sports. Others function as more personal online diaries and some function as online brand advertising of a particular individual or company. A typical blog combines text, digital images, and links to other blogs of the same blog owner, web pages, and other media related to its topic.

A blogger is a person who owns or runs a blog or a person who maintains the blog. That is, posting articles or new posts, information, sharing the most up-to-date news, opinions and case studies to name but a few. Such entries are known as blog posts.

One can earn online by creating the blog, it’s not enough to create a blog only if anyone wants to earn by blogging he/she has to pay attention and time to maintain the blog by posting useful posts so that your post attracts traffic to your blog. Remember your audience is your first step towards your earning you have to advertise your blog by using your social contacts like Facebook, Twitter, Google+, Instagram. It’s not one day work it will take more than six months to grow or as per your ephods sometime it takes more than one year, after this, you have to register yourself at Adsense and different ad companies and you will start earning Dollars. In the case of any help, anyone can contact me by email or by commenting on this post. 

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Work online and make Dollars.

Before reading this article I want to confirm you that I don't have any benefit of sharing this information It's just for sake of social welfare so that instead of wasting time on facebook you can earn working at home.

There are so many ways to start work online, by using your computer skills like typing, editing, designing, searching etc.

Your each skill will help you to work online but there are certain prerequisite things like you need to improve your written English so that you can convey your message to the receiver.

You must have social ethics that proves you are well educated. I am sharing two best websites to register and start work today.

Fiverr: - Fiverr is a global online marketplace offering tasks and services, beginning at a cost of $5 per job performed, from which it gets its name. 

The site is primarily used by freelancers who use Fiverr to offer services to customers worldwide. Currently, Fiverr lists more than three million services on the site that range between $5 and $500. 

Fiverr takes 20% of you earning for promoting your gig and providing you its platform for working online.Click link blew to go on the Fiverr.

www.fiverr.com

Up work:- Upwork, formerly is a global freelancing platform where businesses and independent professionals connect and collaborate remotely. 

Upwork has twelve million registered freelancers and five million registered clients. Three million jobs are posted annually, worth a total of $1 billion USD, making it the world's largest freelancer marketplace. click link blew and register.

www.upwork.com

In the case of any help, you can comment on this post.

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PROCESS SYNCHRONIZATION and RACE CONDITION

·         Process synchronization refers to the idea that multiple processes are to join up or handshake at a certain point, in order to reach an agreement or commit to a certain sequence of action.

(to meet in such a way to reach the processes to completion, not to reach to deadlock)

·         Process Synchronization means sharing system resources by processes in such a way that, Concurrent access to shared data is handled thereby minimizing the chance of inconsistent data. 

·         Process Synchronization was introduced to handle problems that arose while multiple process executions. Some of the problems are:

1.      Critical problem

2.      Synchronization hardware

3.      Mutex locks

4.      Semaphores

RACE CONDITION

A situation like this, where several processes access and manipulate the same data concurrently and the outcome of the execution depends on the particular order in which the access takes place, is called a race condition.

A race condition is an undesirable situation that occurs when a device or system attempts to perform two or more operations at the same time, but because of the nature of the device or system, the operations must be done in the proper sequence to be done correctly.

A race condition occurs when two or more threads can access shared data and they try to change it at the same time. 

Determine the order in which threads attempt to access the shared data

Because the thread scheduling algorithm can swap between threads at any time, you don't know the order in which the threads will attempt to access the shared data. Therefore, the result of the change in data is dependent on the thread scheduling algorithm, i.e. both threads are "racing" to access/change the data.

Example 1: producer-consumer example:

producer:         MOV R1, counter       (R1 = 5)

INC R1                       (R1 = 6)

consumer:        MOV R2, counter       (R2 = 5)

DEC R2                      (R2 = 4)

Producer:         MOV counter, R1       (counter = 6)

Consumer:       MOV counter, R2       (counter = 4)

The value of count will be 4, where the correct result should be 5. The value of count could also be 6 if producer executes MOV counter, R1 at the end. The reason for this State is that we allowed both processes to manipulate the variable counter concurrently. A situation likes this, where several processes access and manipulate the same data concurrently and the outcome of the manipulation depends on the particular order in which the access takes place, is called a race condition.

Example 2:

Thread 1: reads x, value is 7

Thread 1: add 1 to x, value is now 8

Thread 2: reads x, value is 7

Thread 1: stores 8 in x

Thread 2: adds 1 to x, value is now 8

Thread 2: stores 8 in x

How to avoid race conditions

To guard against such race conditions, we require synchronization of processes. A race condition occurs when two or more threads can access shared data and they try to change it at the same time. The main reason is the data is shared. So we implement some locking mechanism. Race conditions can be avoided by employing some sort of locking mechanism before the code that accesses the shared resource:

for ( int i = 0; i < 10000000; i++ )

{

   //lock x

   x = x + 1;

   //unlock x

}

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Polymorphism

Polymorphism is a feature of OOP that allows one interface to be used for a general class of actions. The specific action is determined by the exact nature of the situation. By dint of polymorphism, it is possible to design a generic interface to a group of related activities. This helps reduce complexity by allowing the same interface to be used to specify a general class of action. It is the compiler’s job to select the specific action as it applies to each situation.

The programmer does not need to make the selection manually. He needs only remember and utilize the general interface. In this way, polymorphism promotes extensibility.

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Features of object-oriented programming over the procedure-oriented and Java as platform independence

Java makes platform independence possible by translating a program into bytecode instead of machine code. Bytecode is a highly optimized set of instructions designed to be executed by the Java run-time system or JVM (Java Virtual Machine). Translating a Java program into bytecode makes it much easier to run a program in a wide variety of environments because only the JVM needs to be implemented for each platform. Once the run-time package exists for a given system, any Java program can run on it.

Although the details of the JVM will differ from platform to platform, all understand the same Java bytecode. If a Java program were compiled to native code, then different versions of the same program would have to exist for each type of CPU. Thus, the execution of bytecode by the JVM is the easiest way to create truly portable programs.

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There are three principles of OOP short definations

Encapsulation
Inheritance
Polymorphism

Encapsulation is the mechanism that binds together code and the data it manipulates and keeps both safe from outside interference and misuse. 

Inheritance is the process by which one object acquires the properties of another object. By use of inheritance, an object would need only to define those qualities that make it unique within its class. It can inherit its general attributes from its parent. Thus, it is the inheritance mechanism that makes it possible for one object to be a specific instance of a more general case.

Polymorphism is a feature that allows one interface to be used for a general class of actions. The specific action is determined by the exact nature of the situation.

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DEADLOCKS and METHODS FOR HANDLING DEADLOCKS in OS

In a multiprogramming environment, several processes may compete for a finite number of resources. A process requests resources; if the resources are not available at that time, the process enters a waiting state.

Coming to definition

Sometimes, a waiting process is never again able to change state, because the resources it has requested are held by other waiting processes. This situation is called a deadlock. The principle of Deadlock can be defined as the permanent blocking of a set of processes that either competes for system resources or communicate with each other. A situation in which two or more processes are unable to proceed because each is waiting For one of the others to do something. A set of processes is deadlocked (is in a deadlocked state) when each process in the set is blocked waiting for an event that can only be triggered (caused) by another blocked process in the set. All deadlocks involve conflicting needs for resources by two or more processes. This is what we call the set of processes in the deadlock. A common example is the traffic deadlock. A figure shows a situation in which four cars have arrived at a four-way stop intersection at approximately the same time.

If all four cars ignore the rules and proceed (cautiously) into the intersection at the same time, then each car sizes /occupies /reserves / finishes one resource (one quadrant) but cannot proceed because the required second resource has already been seized by another car. This is an actual deadlock.

Resemblance of deadlock with Kansas legislature’s law

Perhaps the best illustration of a deadlock can be drawn from a law passed by the Kansas legislature early in the 20th century. It said, in part: “When two trains approach each other at a crossing, both shall come to a full stop and neither shall start up again until the other has gone.”

 In which situations, the deadlock becomes common

Deadlock problems can only become more common, given current trends, including larger numbers of processes, multithreaded programs, many more resources within a system, and an emphasis on long-lived file and database servers rather than batch systems.

METHODS FOR HANDLING DEADLOCKS

Generally speaking, we can deal with the deadlock problem in one of three ways. We can use a protocol to prevent or avoid deadlocks, ensuring that the system will never enter a deadlocked state. We can allow the system to enter a deadlocked state, detect it, and recover. We can ignore the problem altogether and pretend that deadlocks never occur in the system. The third solution is the one used by most operating systems, including Linux and Windows.

These three ways result in the following general methods of handling deadlocks:

Deadlock prevention It provides a set of methods to ensure that at least one of the necessary conditions (Mutual exclusion, Hold and wait, No preemption, Circular wait) cannot hold.

Deadlock avoidance requires that the operating system is given additional information in advance concerning which resources a process will request and use during its lifetime. With this additional knowledge, the operating system can decide for each request whether or not the process should wait.

To decide whether the current request can be satisfied or must be delayed, the system must consider the resources currently available, the resources currently allocated to each process, and the future requests and releases of each process.

To ensure that deadlocks never occur, the system can use either a deadlock prevention or a deadlock avoidance scheme.

Deadlock Detection: If a system does not employ either a deadlock-prevention or a deadlock avoidance algorithm, then a deadlock situation may occur. In this environment, the system may provide an algorithm that examines the state of the system to determine whether a deadlock has occurred and that algorithm will recover the system from the deadlock.

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PAGE REPLACEMENT ALGORITHMS in OS

PAGE REPLACEMENT ALGORITHMS

In general, we want a page replacement algorithm with the lowest page-fault rate.

We evaluate an algorithm by running it on a particular string of memory references and computing the number of page faults on that string.

To determine the number of page faults for a particular reference string and page replacement algorithm, we also need to know the number of page frames available.

Obviously, as the number of frames available increases, the number of page faults decreases.

(Expected relationship between number of free frames allocated to a process and the number of page faults caused by it).

FIFO Page Replacement

The simplest page-replacement algorithm is a FIFO algorithm. 

When a page must be replaced, the oldest page is chosen.

We can create a FIFO queue to hold all pages in memory. We replace the page at the head of the queue. When a page is brought into memory we insert t at the tail of the queue. 

Example: consider the reference string: 7, 0, 1, 2, 0, 3, 0, 4, 2, 3, 0, 3, 2, 1, 2, 0, 1, 7, 0, 1

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BASIC ELEMENTS OF COMPUTER

A computer consists of the processor, memory, and I/O components, with one or more modules of each type. These components are interconnected in some fashion to achieve the main function of the computer, which is to execute programs. Thus, there are four main structural elements:

1.      Processor: Controls the operation of the computer and performs its data processing functions. When there is only one processor, it is often referred to as the central processing unit (CPU).

2.      Main memory: Stores data and programs. This memory is typically volatile; that is when the computer is shutdown, the contents of the memory are lost. In contrast, the contents of disk memory are retained even when the computer system is shut down. Main memory is also referred to as real memory or primary memory.

3.      I/O modules: Move data between the computer and its external environment. The external environment consists of a variety of devices, including secondary memory devices (e.g., disks), communications equipment, and terminals. An I/O module transfers data from external devices to processor and memory, and vice versa. It contains internal buffers for temporarily holding data until they can be sent on.

4.       System bus: Provides for communication among processors, main memory, and I/O modules.

The figure depicts these top-level components. One of the processor’s functions is to exchange data with memory. For this purpose, it typically makes use of two internal (to the processor) registers: MAR And MBR

MAR: Memory addresses register (MAR), which specifies the address in memory for the next read or write.

MBR memory buffer register (MBR): This contains the data to be written into memory or which receives the data read from memory.

I/O addresses register (I/OAR) specifies a particular I/O device.

An I/O buffer register (I/OBR) is used for the exchange of data between an I/O module and the processor.

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