cpp/language/attributes/optimize for synchronized

Indicates that the function definition should be optimized for invocation from a synchronized statement.

Explanation
Applies to the name being declared in a function declaration, which must be the first declaration of the function.

Indicates that the function definition should be optimized for invocation from a synchronized statement. In particular, it avoids serializing synchronized blocks that make a call to a function that is transaction-safe for the majority of calls, but not for all calls.