Checkpoint synchronization: Difference between revisions

Make sure that the solution is [[Race condition|race condition]]-free. Note that a straightforward solution based on [[event]]s is exposed to [[Race condition|race condition]]. Let two [[task]]s A and B need to be synchronized at a checkpoint. Each signals its event (''EA'' and ''EAEB'' correspondingly), then waits for the AND-combination of the events (''EA''&''EB'') and resets its event. Consider the following scenario: A signals ''EA'' first and gets blocked waiting for ''EA''&''EB''. Then B signals ''EB'' and loses the processor. Then A is released (both events are signaled) and resets ''EA''. Now if B returns and enters waiting for ''EA''&''EB'', it gets lost.