4.2.05. Guarantee cost

  • T2 ends up waiting for read access to X
  • Either after T1 finished
    • T1 cannot release X even though it has finished using it
    • Incorrect phase (still expanding)
  • Or before T1 has used it
    • T1 has to claim X during expansion, even if it doesn’t use
      it until later
  • Cost: limits the amount of concurrency