Continuing the example from if there were eight threads, at what value of W would the probability of false conflicts exceed 50%? Instead of buffering writes in a redo log, an STM implementation could...

Continuing the example from if there were eight threads, at what value of W would the probability of false conflicts exceed 50%?

Instead of buffering writes in a redo log, an STM implementation could update locations while it was executing, and maintain an undo log for restoring values if the transaction aborted. A subtle complication arises: When the transaction aborts, it cannot restore the old value of orecs when it releases them. Why not? Con-sider the case where transactionT1performs a write to location X and then aborts while reading location Y, and transactionT2performs a read to location X that is concurrent with both ofT1’s operations.