Figure 5. Race Condition.

A race condition occurs when two processes share asynchronous access to a variable, which can lead to unpredictable changes in a variable if two processes race each other to modify the variable value. A GUI allows users to change the temperature setpoint value while the protocol program sinusoidally oscillates the temperature setpoint value. A 5°C increase in the oscillation offset from the user could be nullified by the protocol program if its operations on the variable were concurrent with the bioreactor operations (uncontrolled data access). Synchronous access to the variable guaranties that the bioreactor program's change will not be nullified by the protocol program (controlled data access).