Michael Chow wrote:
Is there a possibility, when for example, counting a certain request, that a highly coincidental retrieval of information by two clients will override eachother's contributions? Suppose you have:
counter +=1 counter.save
If another request gets the initial counter value before the first one had time to save, and then the first one saves, then the second one saves, the counter is only updated by 1 instead of 2.
Does rails somehow protect itself from this kind of possibility? To be honest I'm not particularly familiar with server side applications, do they run in parallel or do they always finish processing the first request before serving the next?
A Rails process currently serializes requests, so there is no problem unless you run multiple Rails processes to increase server capacity.
But this is done very commonly, so you should allow for concurrency by instead writing counter updates directly to the database:
model = Model.find(:first) Model.increment_counter(:counter, model.id)
