Лаба. Англ. Учебное пособие Москва Издательство мгту им. Н. Э. Баумана 2022 удк 81 378(075) ббк 81. 2 Англ С00
 Скачать 0.6 Mb.
|
|
Parallel and Distributed Computing The simultaneous growth in availability of big data and in the number of simultaneous users on the Internet places particular pressure on the need to carry out computing tasks “in parallel,” or simultaneously. Parallel and distributed computing occurs across many different topic areas in computer science, including algorithms, computer architecture, networks, operating systems, and software engineering. During the early 21st century there was explosive growth in multiprocessor design and other strategies for complex applications to run faster. Parallel and distributed computing builds on fundamental systems concepts, such as concurrency, mutual exclusion, consistency in state/memory manipulation, message-passing, and shared-memory models. Creating a multiprocessor from a number of single CPUs requires physical links and a mechanism for communication among the processors so that they may operate in parallel. Tightly coupled multiprocessors share memory and hence may communicate by storing information in memory accessible by all processors. Loosely coupled multiprocessors, including computer networks, communicate by sending messages to each other across the physical links. Computer scientists have investigated various multiprocessor architectures. For example, the possible configurations in which hundreds or even thousands of processors may be linked together are examined to find the geometry that supports the most efficient system throughput. A much-studied topology is the hypercube, in which each processor is connected directly to some fixed number of neighbors: two for the two-dimensional square, three for the three-dimensional cube, and similarly for the higher-dimensional hypercubes. Computer scientists also investigate methods for carrying out computations on such multiprocessor machines (e.g., algorithms to make optimal use of the architecture and techniques to avoid conflicts in data transmission). The machine-resident software that makes possible the use of a particular machine, in particular its operating system, is an integral part of this investigation. Concurrency refers to the execution of more than one procedure at the same time (perhaps with the access of shared data), either truly simultaneously (as on a multiprocessor) or in an unpredictably interleaved order. Modern programming languages such as Java include both encapsulation and features called “threads” that allow the programmer to define the synchronization that occurs among concurrent procedures or tasks. Two important issues in concurrency control are known as deadlocks and race conditions. Deadlock occurs when a resource held indefinitely by one process is requested by two or more other processes simultaneously. As a result, none of the processes that call for the resource can continue; they are deadlocked, waiting for the resource to be freed. An operating system can handle this situation with various prevention or detection and recovery techniques. A race condition, on the other hand, occurs when two or more concurrent processes assign a different value to a variable, and the result depends on which process assigns the variable first (or last). Preventing deadlocks and race conditions is fundamentally important, since it ensures the integrity of the underlying application. A general prevention strategy is called process synchronization. Synchronization requires that one process wait for another to complete some operation before proceeding. For example, one process (a writer) may be writing data to a certain main memory area, while another process (a reader) may want to read data from that area. The reader and writer must be synchronized so that the writer does not overwrite existing data until the reader has processed it. Similarly, the reader should not start to read until data has been written in the area. With the advent of networks, distributed computing became feasible. A distributed computation is one that is carried out by a group of linked computers working cooperatively. Such computing usually requires a distributed operating system to manage the distributed resources. Important concerns are workload sharing, which attempts to take advantage of access to multiple computers to complete jobs faster; task migration, which supports workload sharing by efficiently distributing jobs among machines; and automatic task replication, which occurs at different sites for greater reliability. MODULE 3 1. Read and translate the following text into Russian. Online Privacy Are you worried about your private information being stolen online? The internet is an evolving collaborative effort that has made many tasks easier. However, we are now learning that this could come at a cost: our privacy. Do you trust that your Facebook accounts are safe? Are you worried that your private email accounts may be hacked? You are not alone. Most people do not believe that Facebook, Twitter, or Instagram keep their information fully confidential. In recent news, we have learned that, in fact, we are regularly spied on without our consent. It has been revealed that the NSA (the National Security Agency in the USA) is secretly running a sophisticated spying program on most users connected to the internet from multiple countries and numbering billions of web users. It is uncomfortable knowing that someone else may be reading those private messages you send. Spying in the form of hacking, tracking, and identity theft are all cybercrimes that invade our privacy. Hacking Hacking is trying to get access to unauthorized information on a computer or network. Using a variety of methods, hackers are able to bypass a website’s firewall and gain access to users’ personal data. Some of these hackers can bring down huge networks and cause all sorts of headaches for both website owners and their users. Historically, hackers have caused data breaches resulting in millions of accounts being exposed and personal data being leaked. In 2013, a company called Adobe informed the public of a privacy breach where a hacker stole more than 153 million user records. Again, in 2016, the website Adult Friend Finder recorded a breach of more than 400 million accounts being exposed. In 2019, Canva, a graphic design company, was hacked, resulting in a breach of 137 million accounts. These breaches of information exposed users’ personal information, such as their names, addresses, accounts, and passwords. Due to the growing number of data breaches, it is always recommended that users do not use the same password for all of their accounts. Tracking Tracking on the internet is more common now than ever. Tracking is one of the most common ways companies gather our data. When our online spending habits and online behavior is collected to learn our preferences, we are being tracked. For marketing purposes, companies use this information to target ads to us. Computer algorithmslearn what we are doing and what products we may be interested in buying. We are constantly sharing details about ourselves and bots study who we are. This is why we often see ads catered to our tastes. If you have recently searched for terms such as “the best smartphone”, you will soon notice advertisements selling smart phones will soon appear on your browser. Tracking usually happens when you accept “cookies”, not the edible kind, but a program used to record our data. If sites ask permission, this activity is not illegal. Allowing these cookies gives permission for the site to start collecting your data. When you accept cookies, this data is gathered by either a first-party or third-party company. While many of us don’t seem to mind that computers are studying our every move, others feel that this is a breach of privacy. Surveillance Surveillance is another type of privacy concern that can be much more serious than tracking. Without consent, surveillance can occur in a few ways, and this is illegal. Computer surveillance as well as network surveillance is the monitoring of both online information posted on the internet by its users or the monitoring of hardware devices. Unlike tracking, this monitoring is carried out with no consent and done covertly by companies, hackers or even governments. Thanks to Edward Snowden, a former employee of the NSA, we are all now aware that the government is capable of, and does, have the means to monitor what we do online. They may even have the capability to spy on us via our webcams. This intrusion of privacy is completely illegal. However, this activity is widespread and is known to occur regularly. With access to nearly all private information online, some of the most encrypted sites can still be monitored by authorities. Identity Theft Identity theft of our personal information online is another concerning issue that most affects our privacy online. This is the fastest-growing crime in America, with over 12,000,000 cases last year, costing the average identity theft victim $5,000 in damages. Hackers try to steal personal information including telephone numbers, credit card numbers, social security, and banking information. This stolen information could either be sold or used. This cybercrime is very difficult to investigate by local law enforcement. Social Media Cybercrimes As our addiction to social media grows, so do the cybercriminal attacks on our privacy. Hackers may post fake links on images we may mistake for a friend’s post on Facebook. By clicking on these fake links, we may have just downloaded malware that infects our computer with software that could steal data, crash our devices, and cause hardware damage. Furthermore, data breaches on social media sites are especially worrying. The infamous data breach involving Cambridge Analytica and Facebook (disclosed in 2018) shows how information on social media can be used to change the outcome of national elections or be used to silence one political agenda over another. These actions should make us all think twice before overlooking how important our privacy is while online. Phishing Scams Phishing is another cybercrime confusing a vast amount of internet users regularly. Phishing scams occur when fraudsters pose as an official organization or company asking for private financial or personal information. These scams are usually conducted in the form of an email. They are very confusing to distinguish from official emails for many people. If you receive any suspicious email asking for private information, it is best to call the organization first to confirm if it is genuine. Cyberstalking Stalking is when a person is being followed, watched, or harassed by another in a series of encounters over a period of time. This form of harassment also occurs online. When it does, it is called cyberstalking. Like all cybercrimes, cyberstalking is on the rise as social media users are easy targets for stalkers. As we share more and more of our personal life online, from daily Facebook posts to personal thoughts and opinions, cyber stalkers have more opportunity to harass social media users. By sending unwanted messages, threats, or constantly leaving negative comments online, cyber stalkers have easy access to their victims. This form of privacy invasion is only going to increase as we become more and more plugged into the internet. Due to the anonymity of the internet, it is not easy to stop cyber stalkers from harassing their victims unless tech companies become more responsible and involved in the content of their websites. All of these online privacy concerns should make us more careful and more aware of how easily we can lose our privacy and our freedoms in the ever-changing online environment we are constantly adapting to. 2. Read the following text and render it in English. Online Shopping Tips Think before you click: Beware of emails, texts or other promotions that seem “off” or encourage you to urgently click on links. If you receive an enticing offer, do not click on the link. Instead, go directly to the company’s website to verify the offer is legitimate. If you can’t find it on their website, report the scam to your email provider as a phishing attempt. Remember: if it seems too good to be true, it probably is. Do your homework: Fraudsters are fond of setting up fake e-commerce sites. Prior to making a purchase, read reviews to hear what others say about the merchant. Check trusted sources, like the Better Business Bureau, as well. In addition, look for a physical location and any customer service information. It’s also a good idea to call the merchant to confirm that they are legitimate. Consider your payment options: Using a credit card is much better than using a debit card; there are more consumer protections for credit cards if something goes awry. Or, you can use a third party payment service instead of your credit card. There are many services you can use to pay for purchases – like Google Pay ₋ without giving the merchant your credit card information directly. Watch what you give away: Be alert to the kinds of information being collected to complete your transaction. If the merchant is requesting more data than you feel comfortable sharing, cancel the transaction. You only need to fill out required fields at checkout and you should not save your payment information in your profile. If the account autosaves it, after the purchase go in and delete the stored payment details. Keep tabs on your bank and credit card statements: Be sure to continuously check your accounts for any unauthorized activity. Good recordkeeping goes hand-in-hand with managing your cybersecurity. Another tip for monitoring activity is to set up alerts so that if your credit card is used, you will receive an email or text message with the transaction details. Basic Safety and Security Tips Keep a clean machine: Be sure that all internet-connected devices ‒ including PCs, smartphones and tablets ‒ are free from malware and infections by running only the most current versions of software and apps. These updates protect your devices form any new threats or vulnerabilities. Lock down your login: Create long and unique passphrases for all accounts and use multi-factor authentication (MFA) wherever possible. MFA will fortify your online accounts by enabling the strongest authentication tools available, such as biometrics or a unique one-time code sent to your phone or mobile device. Use a secure Wi-Fi: Using public Wi-Fi to shop online while at your favorite coffee shop is tremendously convenient, but it is not cyber safe. Don’t make purchases via public Wi-Fi; instead use a Virtual Private Network (VPN) or your phone as a hotspot. Or, save those purchases in your cart for later and wait until you’re home and on your own secure network. Give the Gift of Peace of Mind Purchasing an internet-connected device for a loved one? Don’t assume they know how to use it securely. Take a moment to teach recipients how to configure privacy and security settings, set up a strong password, and deactivate any features they don’t need. Don’t let your loved ones learn the hard way. If you give them a device, also give them the gift of peace of mind. 3. Read the following text and render it in English. Social and Professional Issues Computer scientists must understand the relevant social, ethical, and professional issues that surround their activities. The ACM Code of Ethics and Professional Conduct provides a basis for personal responsibility and professional conduct for computer scientists who are engaged in system development that directly affects the general public. As the computer industry has developed increasingly powerful processors at lower costs, microprocessors have become ubiquitous. They are used to control automated assembly lines, traffic signal systems, and retail inventory systems and are embedded in consumer products such as automobile fuel-injection systems, kitchen appliances, audio systems, cell phones, and electronic games. Computers and networks are everywhere in the workplace. Word and document processing, electronic mail, and office automation are integrated with desktop computers, printers, database systems, and other tools using wireless networks and widespread Internet access. Such changes ultimately make office work much more efficient, though not without cost for purchasing and frequently upgrading the necessary hardware and software as well as for training workers to use the new technology. Computer-integrated manufacturing (CIM) is a technology arising from the application of computer science to manufacturing. The technology of CIM emphasizes that all aspects of manufacturing should be not only computerized as much as possible but also linked together via a network. For example, the design engineer’s workstation should be linked into the overall system so that design specifications and manufacturing instructions may be sent automatically to the shop floor. The inventory databases should be connected as well, so product inventories may be incremented automatically and supply inventories decremented as manufacturing proceeds. An automated inspection system (or a manual inspection station supplied with online terminal entry) should be linked to a quality-control system that maintains a database of quality information and alerts the manager if quality is deteriorating and possibly even provides a diagnosis as to the source of any problems that arise. Automatically tracking the flow of products from station to station on the factory floor allows an analysis program to identify bottlenecks and recommend replacement of faulty equipment. For example, computer technology has been incorporated into automobile design and manufacturing. Computers are involved (as CAD systems) not only in the design of cars but also in the manufacturing and testing process. Modern automobiles include numerous computer chips that analyze sensor data and alert the driver to actual and potential malfunctions. Although increased reliability has been achieved by implementing such computerization, a drawback is that only automotive repair shops with a large investment in high-tech diagnostic tools for these computerized systems can handle any but the simplest repairs. The rapid growth of smartphones has revolutionized the telephone industry. Individuals often abandoned their landlines in favor of going completely mobile; the reluctance to pay twice for telephone service was the major driver in this decision. The telephone system itself is simply a multilevel computer network that includes radio wave links and satellite transmission, along with software switches to route calls to their destinations. If one node through which a cross-country call would normally be routed is very busy, an alternative routing can be substituted. A disadvantage is the potential for dramatic and widespread failures; for example, a poorly designed routing and flow-control protocol can cause calls to cycle indefinitely among nodes without reaching their destinations unless a system administrator intervenes. Banking and commerce have been revolutionized by computer technology. Thanks to the Internet, individuals and organizations can interact with their bank accounts online, performing fund transfers and issuing checks from the comfort of their homes or offices. Deposits and withdrawals are instantly logged into a customer’s account, which is stored on a remote server. Computer-generated monthly statements are unlikely to contain errors. Credit and debit card purchases are also supported by computer networks, allowing the amount of a transaction to be immediately deducted from the customer’s account and transferred to the seller’s. Similarly, networks allow individuals to obtain cash instantly and almost worldwide by stepping up to an automated teller machine (ATM) and providing the proper card and personal identification number (PIN). The security challenges associated with these technologies are significant. Intruders can intercept packets traveling on a network (e.g., being transported via a satellite link) and can decrypt them to obtain confidential information on financial transactions. Network access to personal accounts has the potential to let intruders not only see how much money an individual has but also transfer some of it elsewhere. Fortunately, increased software security measures have made such intrusions less likely. Computer technology has had a significant impact on the retail industry. All but the smallest shops in places with Internet access have replaced the old-fashioned cash register with a terminal linked to a computer system. Some terminals require that the clerk type in the code for the item, but most checkout counters include a bar-code scanner, which reads into the computer the Universal Product Code (UPC) printed on each package. Cash register receipts then include brief descriptions of the items purchased (by fetching them from the computer database), and the purchase information is also relayed back to the computer to cause an immediate adjustment in the inventory data. The inventory system can easily alert the manager when the supply of an item drops below a specified threshold. In the case of retail chains linked by networks, the order for a new supply of an item may be automatically generated and sent electronically to the supply warehouse. In a less extensively automated arrangement, the manager can send in the order electronically by a direct link to the supplier’s computer. These developments have made shopping much more convenient. The checkout process is faster, checkout lines are shorter, and desired items are more likely to be in stock. In addition, cash register receipts contain more detailed information than a simple list of item prices; for example, many receipts include discount coupons based on the specific items purchased by the shopper. Appendix 4 |