I asked this question a while back and didn't really get a definitive response.
https://groups.google.com/d/topic/google-appengine/YRAK6lHV1XQ/discussion (that's the link groups is giving me, but I'm having trouble with it - title of the thread is 'Idempotence & multiple task execution' if you want to search for it). Ikai's response sounded definitive - '*The same task should not be executed multiple times concurrently*'. But the subsequent discussion seemed to cast doubt on that statement and it was never cleared up. I have never seen it happen. The answer to this question makes a difference in how the idempotent contract is implemented - especially whether transactional semantics are required or not. That might sound trivial, but implementing a transaction has significant performance implications, and is not something you would do if you don't need to. I disagree that 'make it idempotent' is a sufficient answer to this question. It is reasonable to want to understand the constraints of the task queue and make implementation decisions on that basis. Cheers, Colin * * * * -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
