MySQL to share memory for many workers in Node.JS (possible?)

Question

Running into a fun scenario where I have many servers running and I am doing my best to route them via IPC but finding this may allow double read before a necessary write takes place. This in turn may give me false counts/values.

I'm looking to setup a database or some type of solution that I can do exactly:

I read database for available server based on lowest counts. The server I pick I update its counts by +1 all in one action. I could have 100s of requests coming in over web socket and need this count accurate for each request to not over-load a server.

My fear is two workers perform the same request at the same time, I'd want one to finish their read/write first before the other but not slow other requests down.

Is this do-able with MySQL or is there a faster solution? I think I need ACID compliant.

Answer 1

Yes, use MySQL (or other database) for common storage between any number of clients. Use "transactions" to keep the clients from stepping on each other:

START TRANSACTION;
do several reads/writes with database, but don't take too long
COMMIT;

When doing reads, use this if you might be changing the rows fetched:

SELECT ... FOR UPDATE;

That way you effectively prevent other threads from messing with the rows before you get to a subsequent UPDATE or DELETE .