Parallel computing those that use concurrency, are more difficult to write than sequential ones, because concurrency introduces several new classes of potential software bugs, of which race conditions are the most common. Communication and synchronization between the different subtasks are typically some of the greatest obstacles to getting good parallel program performance. A theoretical upper bound on the speed-up of a single program as a result of parallelization is given by Amdahl's law. Traditionally, computer software has been written for serial computation. To solve a problem, an algorithm is constructed and implemented as a serial stream of instructions. These instructions are executed
Serial killer that serial killers are always white might have become "truth" in some research fields due to the over-reporting of white serial killers in the media. According to some sources, the percentage of serial killers who are African American is estimated to be between 13% and 22%. Another study has shown that 16% of serial killers are African American, what author Maurice Godwin describes as a "sizeable portion". A 2014 Radford/FGCU Serial Killer Database annual statistics report indicated that for the decades 1900–2010, the percentage of white serial killers was 52.1% while the percentage of African American serial killers was 40.3%.