Instruct: Given a question, retrieve passages that answer the question.
Query: What is a race condition?
Race conditions arise in software when an application depends on the sequence or timing of processes or threads for it to operate properly. As with electronics, there are critical race conditions that result in invalid execution and bugs. Critical race conditions often happen when the processes or threads depend on some shared state. Operations upon shared states are critical sections that must be mutually exclusive. Failure to obey this rule opens up the possibility of corrupting the shared state.
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An IP address conflict occurs when two devices on the same local physical or wireless network claim to have the same IP address. A second assignment of an address generally stops the IP functionality of one or both of the devices. Many modern operating systems notify the administrator of IP address conflicts. If one of the devices is the gateway, the network will be crippled. When IP addresses are assigned by multiple people and systems with differing methods, any of them may be at fault.
Rally is a form of motorsport that takes place on public or private roads with modified production or specially built road-legal cars. It is distinguished by running not on a circuit, but instead in a point-to-point format in which participants and their co-drivers drive between set control points (special stages), leaving at regular intervals from one or more start points. Rallies may be won by pure speed within the stages or alternatively by driving to a predetermined ideal journey time within the stages.
Supporters note that this is a modern condition: when NASCAR first started in 1948, the race cars were indeed production vehicles, but the safety and performance needs of modern racing have required custom-built race cars. Supporters also note that the strict equipment rules place less emphasis on getting a technological advantage, and thus more emphasis on individual driver skill. All of NASCAR's series also run on spec tires made by certain tire manufacturers such as Goodyear and American Racer. Some suggest that this discourages tire competition and development, which they further assert has led to the absence of rain/wet condition tires, and to races (such as the 2005 UAW-GM Quality 500) where tires seem to self-destruct. The lack of tire competition has also helped lead to a drop in the number of new winners; in 1994 when Hoosier Racing Tire participated the sport saw three new winning drivers (Sterling Marlin, Jimmy Spencer, and Jeff Gordon) and the competitive elevation of drivers such as Ward Burton and his brother Jeff.
At the 2014 24 Hours of Le Mans, the No. 20 entry, driven by Mark Webber at the time, closed to within one minute of the leading No. 1 Audi R18 e-tron quattro with an hour and a half of the race remaining when the car suffered a broken anti-roll bar. Before the hour was out, Marc Lieb was forced to pit the No. 14 entry with the same issue. Car No. 14 returned to the circuit to complete a ceremonial lap at the end of the race and was classified eleventh overall, but car No. 20 was unable to take to the circuit and was not officially classified as finishing, despite having completed 90% of the winner's race distance.
In 1913, Georges Sagnac showed that if a beam of light is split and sent in two opposite directions around a closed path on a revolving platform with mirrors on its perimeter, and then the beams are recombined, they will exhibit interference effects. From this result Sagnac concluded that light propagates at a speed independent of the speed of the source. The motion of the earth through space had no apparent effect on the speed of the light beam, no matter how the platform was turned. The effect had been observed earlier (by Harress in 1911), but Sagnac was the first to correctly identify the cause.
A type of hybrid between the purism of open-wheelers and the familiarity of touring car racing, this style is often associated with the annual Le Mans 24 Hours endurance race. First run in 1923, Le Mans is one of the oldest motor races still in existence. Other classic but now defunct sports car races include the Italian classics, the Targa Florio (1906–1977) and Mille Miglia (1927–1957), and the Mexican Carrera Panamericana (1950-1954). Most top class sports car races emphasize endurance (typically between 2.5–24 hours), reliability, and strategy, over pure speed. Longer races usually involve complex pit strategy and regular driver changes. As a result, sports car racing is seen more as a team endeavor than an individual sport, with team managers such as John Wyer, Tom Walkinshaw, driver-turned-constructor Henri Pescarolo, Peter Sauber and Reinhold Joest becoming almost as famous as some of their drivers.
HTTP is a stateless protocol. A stateless protocol does not require the HTTP server to retain information or status about each user for the duration of multiple requests. However, some web applications implement states or server side sessions using for instance HTTP cookies or hidden variables within web forms.
Reactive hypoglycemia, postprandial hypoglycemia, or sugar crash is a term describing recurrent episodes of symptomatic hypoglycemia occurring within four hours after a high carbohydrate meal in people both with and without diabetes. The term is not necessarily a diagnosis since it requires an evaluation to determine the cause of the hypoglycemia.
Riddle contemplated entering Man o' War against older horses for the first time in the $5,000 Saratoga Gold Cup, but ultimately chose to enter the $15,000 Lawrence Realization Stakes against three-year-olds instead. When his only rival scratched from the race, it nearly became a walkover until Mrs. Riddle's niece, Sarah Jeffords, entered Hoodwink. To compensate for the lack of competition, Riddle announced that Man o' War would be allowed to show his speed. Man o' War was reunited with regular jockey Kummer, after being ridden by Sande and Schuttinger while Kummer recovered from an injury. Kummer neither restrained the horse nor urged him on at any point in the race. Running as he pleased, Man o' War won by slightly more than a quarter mile – the official margin was 100 lengths – while setting a new world record of 2:40 4/5 for a mile and five-eighths. This broke the existing world record set in England by seconds and lowered the American record by over four seconds. This world record stood until 1956, when it was broken by Man o' War's great-grandson Swaps.
Since Gateway cloning uses patented recombination sequences, and proprietary enzyme mixes available only from Invitrogen, the technology does not allow researchers to switch vendors and contributes to the lock-in effect of all such patented procedures.
A tic is a sudden, repetitive, nonrhythmic motor movement or vocalization involving discrete muscle groups. Tics can be invisible to the observer, such as abdominal tensing or toe crunching. Common motor and phonic tics are, respectively, eye blinking and throat clearing.
Historically Silverstone has suffered traffic congestion on race days. This problem has been largely eliminated with the completion of the A43 Silverstone bypass, a dual-carriageway road just to the north of the circuit. When the race was moved to an April date in 2000, rainy conditions turned the fields used for car parking into mud baths, causing chaos for spectators trying to park. On F1 race day in 1999 there were some 4200 helicopter journeys made to Silverstone Heliport, which was the busiest airport in the UK on that day.
Third parties, meaning a party other than one of the two dominant parties, are possible in two-party systems, but they are often unlikely to exert much influence by gaining control of legislatures or by winning elections. While there are occasional opinions in the media expressed about the possibility of third parties emerging in the United States, for example, political insiders such as the 1980 presidential candidate John Anderson think the chances of one appearing in the early twenty-first century is remote. A report in "The Guardian" suggested that American politics has been "stuck in a two-way fight between Republicans and Democrats" since the Civil War, and that third-party runs had little meaningful success.
A generic drug is a chemically equivalent, cheaper version of a brand-name drug. A generic drug form is required to have the same dose, strength and active ingredient(s) as the brand name drug; thus, they carry the same risks and benefits. To ensure compliance, the FDA Generic Drugs Program conducts stringent reviews (3,500 inspections of manufacturing plants per year). Although generic drugs sound like a great money-saver, generic medicines can only be sold after the patents of the brand name versions end. Because of this mandatory period of exclusivity for many brand-name drugs (a period in which generic medicines cannot be sold), delay of generic drugs reaching the market is expected. The high cost of upfront research that the brand-name products have to go through to ensure safety and efficacy largely account for the high discrepancy in pricing between the two groups.
Malware authors target bugs, or loopholes, to exploit. A common method is exploitation of a buffer overrun vulnerability, where software designed to store data in a specified region of memory does not prevent more data than the buffer can accommodate being supplied. Malware may provide data that overflows the buffer, with malicious executable code or data after the end; when this payload is accessed it does what the attacker, not the legitimate software, determines.
The race was marked with some teams boycotting the event due to apartheid – the segregation of blacks and whites – and was the last South African Formula One race until apartheid ended in 1992. The race was won by Nigel Mansell in a Williams-Honda, who also took pole position.
The processes of oxidation and reduction occur simultaneously and cannot happen independently of one another, similar to the acid–base reaction. The oxidation alone and the reduction alone are each called a "half-reaction", because two half-reactions always occur together to form a whole reaction. When writing half-reactions, the gained or lost electrons are typically included explicitly in order that the half-reaction be balanced with respect to electric charge.
In South America, a phenomenon known as the El Nino Oscillation Cycle, between floods and drought on the Pacific Coast has made as much as a 35% difference in Global yields of wheat and grain.
In this case of a race condition, the concept of the "shared resource" covers the state of the network (what channels exist, as well as what users started them and therefore have what privileges), which each server can freely change as long as it signals the other servers on the network about the changes so that they can update their conception of the state of the network. However, the latency across the network makes possible the kind of race condition described. In this case, heading off race conditions by imposing a form of control over access to the shared resource—say, appointing one server to control who holds what privileges—would mean turning the distributed network into a centralized one (at least for that one part of the network operation).
Race conditions are also intentionally used to create hardware random number generators and physically unclonable functions. PUFs can be created by designing circuit topologies with identical paths to a node and relying on manufacturing variations to randomly determine which paths will complete first. By measuring each manufactured circuit's specific set of race condition outcomes, a profile can be collected for each circuit and kept secret in order to later verify a circuit's identity.
Race conditions have a reputation of being difficult to reproduce and debug, since the end result is nondeterministic and depends on the relative timing between interfering threads. Problems occurring in production systems can therefore disappear when running in debug mode, when additional logging is added, or when attaching a debugger, often referred to as a "Heisenbug". It is therefore better to avoid race conditions by careful software design rather than attempting to fix them afterwards.
Many software race conditions have associated computer security implications. A race condition allows an attacker with access to a shared resource to cause other actors that utilize that resource to malfunction, resulting in effects including denial of service and privilege escalation.