The exit() method exits the current domain, popping it off the domain stack. Any time execution is going to switch to the context of a different chain of asynchronous calls, it’s important to ensure that the current domain is exited. The call to exit() delimits either the end of or an interruption to the chain of asynchronous calls and I/O operations bound to a domain.
If there are multiple, nested domains bound to the current execution context, exit() will exit any domains nested within this domain.
Calling exit() changes only the active domain, and does not alter the domain itself. enter() and exit() can be called an arbitrary number of times on a single domain.
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