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.
Suppress false positives by adding the suppression annotation @SuppressWarnings("NoAllocation") to the enclosing element.