|Summary:||Wrong transition selection in systems with process priorities|
|Product:||UPPAAL||Reporter:||Yasufumi Suzuki <yasufumi.suzuki.bq>|
|Component:||Engine||Assignee:||Alexandre David <adavid>|
Description Yasufumi Suzuki 2009-04-03 08:40:46 CEST
A binary synchronization transition of a low priority process is enabled even if a binary synchronization transition of a higher priority process using the same channel is possible. Problem description: This problem occurs only when also a delaying transition in a third process is enabled. It is visible in the last transition in the attached example trace. Example model: see attachment 1 [details] Example trace: see attachment 2 [details]
Comment 3 Alexandre David 2009-08-12 19:05:53 CEST
Fixed in rev. 4378 (4.0.9) and 4379 (trunk). We have changed the semantics because it was inconsistent. Before, priority was resolved by comparing the priorities of the processes involved in two transitions by descending order. Now, it is resolved by considering the highest priority process, which is in line with priority ceiling protocols. In this example, it is normal to have the synchronization with the new semantics (though not normal with the old one).