public abstract class AtnManager
extends Object

Manage ATN to avoid memory leak.

The mutable prediction caches (DFA states, prediction contexts, LL(1) table) live on a private ATN owned by a softly referenced AtnWrapper, not on the generated parser's static ATN. That single decision provides the memory-pressure response: while parsers are active the wrapper is strongly reachable through their interpreters, and once this copy of the runtime goes idle the whole cache graph is only softly reachable, so the collector reclaims it directly — no cleaner thread (which would pin the defining class loader for the life of the JVM, GROOVY-12142), and no clear-on-next-parse canary (which never fires for an idle copy: a build daemon caches one runtime copy per distinct classpath, and every idle copy's fully warmed cache stayed strongly reachable until the daemon spent more time collecting than parsing).

Two deterministic mechanisms bound the cache while a copy is active, and they compose:

• a size ceiling — groovy.antlr4.cache.size DFA states retained across the shared ATN; exceeding it replaces the wrapper with a fresh one. The default scales with the heap so a large daemon keeps a warm working set while a small JVM stays protected.
• a parse counter — replaces the wrapper every groovy.antlr4.cache.threshold parses, for workloads that want a fixed cadence. Off by default.