Jun 04, 2012 kloc is thousands of noncomment source lines of code defect potential is the number of defects bugs that exist in the code from the very start of engineering. Gauging software readiness with defect tracking steve mcconnell. Even most of the process to talk about some % of issues is fine or acceptable quality per kloceven though there is lot of subjectivity. Nasa was able to achieve zero defects for the space shuttle software, but at a. Cost per defect penalizes quality and is always cheapest where the greatest numbers of bugs are found. Is the average number of bugs per loc the same for different. After release, the number would rather be 1 to 5 bugs per kloc in commercial software. In general, for most software quality assurance systems the common software metrics that are checked for improvement are the source lines of code, cyclical complexity of the code, function point analysis, bugs per line of code, code coverage, number of classes and interfaces, cohesion and coupling between the modules etc. We need some way of gauging whether or not our continue reading why defectskloc doesnt supply enough information. If you focus on the product well you know the conundrum about software measurement. Applications are divided into functional areas or more technically kloc thousand lines of code. I have been told that the average number of bugsdefects per line of code is constant for different programming languages. Software quality metrics overview product quality metrics. One method i could think of is using formal methods to proof that the software is correct and count the number of bugs encountered on the way.
Software metrics and programmer productivity my company has recently experimenting about using software metrics to measurecompare productivity of programmers and use it as performance appraisal tool. It is important to consider that just about every device has software, and therefore security vulnerabilities. Good quality in this second case assume that a software engineer spent 15 hours writing test cases, 10. Even with the best validation, its very hard to achieve perfect quality in software.
Other data pegs bug injection rates in the embedded space between 50100 per kloc. As a software developer, is it okay to know where the bug in the code is and. It enables one to decide if a piece of software is ready to be released. Assuming a 100 kloc application with 20 defects per kloc and 5% of the bugs missed, you end up with 100 bugs in your shipped product. The more code you have, the more security bugs you will have.
Introduction to kloc lines of code loc is one of the software metric that is used by most of the people for software measurement. Every layer is subject to the same 1550 bugs per kloc and the corresponding. What fraction of software bugs are security vulnerabilities. Layer upon layer of software increases the attack surfaces that attackers can probe for weaknesses. Thus, the average number of defects in a section or per kloc of a software application is bug density. I know that seems obvious at first, but hear me out, as many refactorings, abstractions, cleaner code increases the loc. The software industry has become one of the largest and most successful industries in history.
True positives per kloc code quality of the open source software total bugs found per kloc qualitative evaluation criteria usability easy to install and run readability precise description of bugs accuracy real bugs or not evaluation approach target functionality of our evaluation findbugs features evaluated. Fenton and pfleeger 2 suggest measuring program reliability, and thus the effectiveness of the software qa process using the number of bugs found per kloc as a metric. An empirical study of bugs in software build systems xin xia. A colleague emailed me a few days ago, and asked for a code base with a given size, what can we expect to see for numbers of defects per kloc given the actual industry average or given what the industry believes we should expect. Collection of software bugs, glitches, errors, disasters like ariane 5, pentium bug, sleipner, patriot, mars climate orbiter, mars sojourner, london millenium bridge. Obviously, software bugs can be security vulnerabilities but also obviously, many software bugs have little or no security impact. Software is a multidimensional concept that can be viewed from many professional and user viewpoints. Covering average bugs per loc stats in his great book code complete. Running the program on carefully selected inputs and checking the results. How to calculate the defect density in software products. Every layer is subject to the same 1550 bugs per kloc and the corresponding exploitable vulnerabilities.
The defect density of a software is counted per thousand lines of the code, which is also known as kloc. What is the average ratio of bugs to a line of code. Even with zero defects there will be costs for inspections, testing, static analysis, and maintenance personnel. This is being implemented on experimental basis in some project groups. The figure given by carnegie mellon university, 20 or 30 bugs per kloc, is definitely not for released software, but probably for written software. Software vulnerability an overview sciencedirect topics. I have been told that the average number of bugs defects per line of code is constant for different programming languages. When you know there is a value and have been able to build something sustianable or i guess in startup world, with a hockey stick growth, you might want to move on from it works to it is best in class.
Why bugfree software doesnt matter by matt asay in security on march 14, 2016, 1. Software failures are not due to consumption phenomena. Software bugs are measured in total number of defects per 1,000 lines of code kloc. Missed bugs are pretty common around 95% of all bugs introduced during embedded software development are found, meaning that five percent remain in the production firmware. Sizeoriented metrics are used to analyze the quality of software with the help of a kloc quantifier. The figure given by carnegie mellon university, 20 or 30 bugs per kloc, is definitely not for released software, but probably for written software before any testing happens. The defect rate metric, ideally, is indexed to the number of functions a software provides. The defect density is arrived at number of bugs kloc per the product under test. Comparing observed bug and productivity rates for java and. Their task is treacherous, treading the line between releasing poor quality software early. On average, 15 errors per kloc kilolinesofcode in mature software 10 bugs per kloc in prototype software windows 2000 35 million lines of code 63,000 known bugs at release time 2 bugs per kloc 7. If defects per unit of functions is low, then the software should have better quality even though the defects per kloc value could be higherwhen the functions were implemented by fewer lines of code. That is, it includes all of the bugs found and fixed in development, plus those that slip out the door.
The results are then divided by the size of that particular module, which allows the team to decide whether the software is ready for the release or whether it requires more testing. Kloc is thousands of noncomment source lines of code defect potential is the number of defects bugs that exist in the code from the very start of engineering. Hi, i just want to know, what is the no of bugs kloc. Feb 28, 2007 so its understood that when the size of the code is more there is a chance for more number of bugs in the prodcut. We need some way of gauging whether or not our continue reading why defectskloc doesnt supply enough information about product quality. Suppose 10 bugs are found in 1 kloc therefore dd is 10kloc. The reason a bug is in there is that nobody has found it. He attributes this to a combination of codereading techniques and independent testing discussed further in another chapter of his book.
This metric helps us in knowing the size and complexity of the software application. Most still resort to bugs per kloc thousand lines of code since its easy to measure. Software security practices should be integrated into the software development lifecycle sdlc software security defects come in two main flavorsbugs at the implementation level code and flaws at the architectural level design badnessometers are not security meters. Now assume the same software is written in java and requires only 2,000 lines of code 2 kloc. You may assume that the terms bug and kloc are welldefined. Defect density is the number of defects confirmed in softwaremodule during a specific period of operation or development divided by the size of the softwaremodule. Here are some typical residual defect rates bugs left over after the software has shipped per kloc one thousand lines of. Here are some typical residual defect rates bugs left over after the software has shipped per kloc one thousand lines of source code.
I write j code, so one error usually amounts to 1 in 5 or 10 loc. Mar 01, 2004 a colleague emailed me a few days ago, and asked for a code base with a given size, what can we expect to see for numbers of defects per kloc given the actual industry average or given what the industry believes we should expect. Sloc is typically used to predict the amount of effort that will be required to develop a program, as well as to estimate programming. Historically software quality metrics have measured exactly the opposite of qualitythat is, the number of defects or bugs per thousand lines of code. Currently main metric being used is no of bugskloc, etc. The last column shows the number of delivered bugs per kloc. Kloc what does it mean to software testing software. But at my previous employer, all the developers were very sharp, but it was a large project, over a million lines of code, with very onerous certification. This is known as the defects per kloc lines of code. Software failures are not random, are deterministic that is. Is there any data or rules of thumb on roughly what fraction of software bugs are also security vulnerabilities.
Gauging software readiness with defect tracking steve. Two leading firms in customerfocused software quality are ibm and hewlettpackard. This is true even though the c version had 65 total defects and the. If defects per unit of functions is low, then the software should have better quality even though the defects per kloc value could be higherwhen the functions were. The advantage of this approach over the defects per thousandsoflinesofcode metric, or kloc,is that it can measure defects in requirements.
Here are some software bugs that took a stab at it. Think of an application as having two measurements the first is total number of defects per kloc, and. Googles android operating system is surprisingly bugfree. Source lines of code sloc, also known as lines of code loc, is a software metric used to measure the size of a computer program by counting the number of lines in the text of the programs source code. If all software has bugs and it is inevitable that some bugs will be security vulnerabilities, all software will have security vulnerabilities. Why is a malfunction or an error in a software program called bug. What fraction of software bugs are vulnerabilities. Everybody always says that they can beat the 10 lines per developer per day from the mythical man month, and starting a project, i can usually get a couple hundred lines in in a day. Why defectskloc doesnt supply enough information about. And since even great programmers top 1% introduce around 11 defects per kloc lines of code, missing 5 % of the bugs is quite significant. In the competitive commercial software market, software companies feel compelled to release software the moment it is ready.
We can predict the remaining defect in the software product by using the defect density. The mean is 18 bugs per kloc and the observed standard deviation is 8. In retrospect function point metrics have proven to be a powerful tool for software economic and quality analysis. Its been hard to get traction in software development due to the difficulty in identifying opportunities for defect. Oct 29, 2014 this is known as the defects per kloc lines of code. According to 22, for software applications developed by microsoft, defect density is about 1020 defects per kloc during inhouse testing and 0. Apr 29, 2020 defect density is the number of defects confirmed in software module during a specific period of operation or development divided by the size of the software module. How to reduce coding defects defect reduction techniques. And testing cant show you that there are no more bugs. May 19, 2016 industry average bugs per lines of code at 1550 and microsoft released code at 0. In a software startup or a feature, you want to find the fastest and cheapest way to verify the value of something. The industry average is between 15 and 50 bugs per lines of codebut a lot.
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