[Idea] Strategies for concurrency

[Duncan Jones]

Business and technology solutions to concurrency issues (like the traditional example of the bank transfer).

• Compensation actions
• As-of read model actions
• State change prevention

[Duncan Jones]

Why do we need solutions to concurrency issues?

Is "fingers crossed" ever a viable strategy?

[ylorph]

Yeah "finger crossed" is viable if it costs less than solving them ;-)

[Savvas Kleanthous]

Or a runbook with "step 1: shout in the room if anyone else is updating global settings. If no-one answers within 2 minutes move to step 2."

[Duncan Jones]

You could have a semaphore (the "I am updating these settings" hat...and there is only one hat) - this would be a form of state change prevention.

[ylorph]

you mean an Xclusive lock :-)

[Savvas Kleanthous]

Well, yeah it is a kind of semaphore, but I mentioned it because it's outside of the system itself and relies on people playing nice and adhering to a workflow. The effort involved is at least one order of magnitude less than any state change prevention in code.

[Duncan Jones]

Working title "What to do if transactions don't exist"...