Software rejuvenation

In software engineering, software aging refers to all software's tendency to fail, or cause a system failure after running continuously for a certain time. As the software gets older it becomes less immune and will eventually stop functioning as it should, therefore rebooting or reinstalling the software can be seen as a short term fix. A proactive fault management method to deal with the software aging incident is software rejuvenation. This method can be classified as an environment diversity technique that usually is implemented through software rejuvenation agents (SRA). In software engineering, software aging refers to all software's tendency to fail, or cause a system failure after running continuously for a certain time. As the software gets older it becomes less immune and will eventually stop functioning as it should, therefore rebooting or reinstalling the software can be seen as a short term fix. A proactive fault management method to deal with the software aging incident is software rejuvenation. This method can be classified as an environment diversity technique that usually is implemented through software rejuvenation agents (SRA). From both an academic and industrial point of view, the software aging phenomenon has increased. The main focus has been to understand its effects from a verifiable observation and theoretical understanding. 'Programs, like people, get old. We can't prevent aging, but we can understand its causes, take steps to limit its effects, temporarily reverse some of the damage it has caused, and prepare for the day when the software is no longer viable.' Memory bloating and leaking, along with data corruption and unreleased file-locks are particular causes of software aging. Software failures are a more likely cause of unplanned systems outages compared to hardware failures. This is because software exhibits over time an increasing failure rate due to data corruption, numerical error accumulation and unlimited resource consumption. In widely used and specialized software, a common action to clear a problem is rebooting because aging occurs due to the complexity of software which is never free of errors. It is almost impossible to fully verify that a piece of software is bug-free. Even high-profile software such as Windows and macOS must receive continual updates to improve performance and fix bugs. Software development tends to be driven by the need to meet release deadlines rather than to ensure long-term reliability. Designing software that can be immune to aging is difficult. Not all software will age at the same rate as some users use the system more intensively than others. To prevent crashes or degradation software rejuvenation can be employed proactively as inevitable aging leads to failures in software systems. This proactive technique was identified as a cost-effective solution during research at the AT&T Bell Laboratories on fault-tolerant software in the 1990s. Software rejuvenation works by removing accumulated error conditions and freeing up system resources, for example by flushing operating system kernel tables, using garbage collection, reinitializing internal data structures, and perhaps the most well known rejuvenation method is to reboot the system. There are simple techniques and complex techniques to achieve rejuvenation. The method most individuals are familiar with is the hardware or software reboot. A more technical example would be the web server software Apache's rejuvenation method. Apache implements one form of rejuvenation by killing and recreating processes after serving a certain number of requests.Another technique is to restart virtual machines running in a cloud computing environment. The multinational telecommunications corporation AT&T has implemented software rejuvenation in the real time system collecting billing data in the United States for most telephone exchanges. Some systems which have employed software rejuvenation methods include: