Race Conditions

• A potential problem; Instructions of cooperating processes can be interleaved arbitrarily. Hence, the order of (some) instructions are irrelevant. However, certain instruction combinations must be eliminated. For example: see Table 2.1
  

  Table 2.1: Race Condition

  Process A	Process B	concurrent access
  A = 1;	B = 2;	does not matter
  A = B + 1;	B = B * 2;	important!

  
  
• A race condition is a situation where two or more processes access shared data concurrently and correctness depends on specific interleavings of operations; final value of shared data depends on timing (i.e., race to access and modify data)
• To prevent race conditions, concurrent processes must be synchronized