What is race condition in OS?

Answer 1

A race condition or race hazard is a flaw in a system or process whereby the output and/or result of the process is unexpectedly and critically dependent on the sequence or timing of other events. The term originates with the idea of two signals racing each other to influence the output first. Race conditions can occur in electronics systems, especially logic circuits, and in computer software, especially multithreaded or distributed programs.

Answer 2

A race condition is a situation when the outcome of a program or event is dependent on the order in which things are executed. This is generally considered a really bad thing. You want programs to always give the same result every time they are executed with the same inputs.

A race condition can occur for example when two different programs are trying to write to the same file. The last one to write to the file will be the one whose changes stay.

Answer 3

A race condition is a condition where the output of a logic circuit is highly dependent on propagation delay, the variation of which can cause the result to be uncertain.

An example might be an 8085 microprocessor data bus buffer on a write cycle. Lets say you turn the bus buffer on and off with the WR- signal. That is an error, because the 8085 is designed to hold the data bus value valid for about one half clock cycle longer, to give the receiving device time to strobe the data bus on the rising edge of WR-. Proper design would hold the buffer output asserted until the following rising edge of CLK, or the rising edge of ALE, all predicated on S1 (and IO/M-) being low.