NoAllocation

Like many other languages, Java provides automatic memory management. In Java, this feature incurs an runtime cost, and can also lead to unpredictable execution pauses. In most cases, this is a reasonable tradeoff, but sometimes the loss of performance or predictability is unacceptable. Examples include pause-sensitive user interface handlers, high query rate server response handlers, or other soft-realtime applications.

In these situations, you can annotate a few carefully written methods with @NoAllocation. Methods with this annotation will avoid allocations in most cases, reducing pressure on the garbage collector. Note that allocations may still occur in methods with @NoAllocation if the compiler or runtime system inserts them.

To ease the use of exceptions, allocations are allowed if they occur within a throw statement. But if the throw statement contains a nested class with methods annotated with @NoAllocation, those methods will be disallowed from allocating.