simultaneous multiple requests to very simple database

[Tom Loredo]

Just learned of this today, so I don't know enough details to judge
its suitability for you:

Durus
http://www.mems-exchange.org/software/durus/

It does not do locking, but alleges to be compact and easy to
understand, so perhaps you could modify it to meet your needs,
or find some other way to handle that requirement.

-Tom

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