[jira] [Assigned] (GROOVY-12259) Make category/bulk call-site invalidation O(live SwitchPoint domains) instead of O(loaded classes)

["Paul King (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/GROOVY-12259?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Paul King reassigned GROOVY-12259:
----------------------------------

    Assignee: Paul King

> Make category/bulk call-site invalidation O(live SwitchPoint domains) instead of O(loaded classes)
> --------------------------------------------------------------------------------------------------
>
>                 Key: GROOVY-12259
>                 URL: https://issues.apache.org/jira/browse/GROOVY-12259
>             Project: Groovy
>          Issue Type: Improvement
>            Reporter: Paul King
>            Assignee: Paul King
>            Priority: Major
>
> GROOVY-12258 made process-wide call-site invalidation a no-op in processes that never link an indy MOP guard (classic-only bytecode). This follow-up addresses the remaining cost for indy and mixed processes: once any indy site has linked, every category enter/leave (and custom-MetaClass / unattributed registry event) still retires domains by walking every loaded class.
> h3. Problem
> {{IndyInvalidation.retireAllLoadedDomains()}} iterates {{ClassInfo.getAllClassInfo()}} — O(all loaded classes), a weak-reference pointer chase over tens of thousands of entries in a framework-sized app — *twice per {{use}} block* (enter and leave), collecting the comparatively few domains that actually hold a live SwitchPoint.
> h3. Proposed fix
> Track live SwitchPoints in a process-wide registry so bulk retirement is O(live domains):
> * {{SwitchPointInvalidator}} gains a static {{ConcurrentHashMap<SwitchPoint, SwitchPointInvalidator>}} of every live SwitchPoint mapped to its owning invalidator. It is keyed by *SwitchPoint*, not invalidator: each SwitchPoint has a single-use lifecycle (allocated once, detached once), so a removal can never clobber a successor's entry the way an invalidator-keyed registry could (ABA on re-allocation).
> * {{getSwitchPoint()}} registers the new SwitchPoint *before* the publishing CAS (and deregisters on CAS loss). The GROOVY-12258 ordering argument carries over: a bulk path that finds no entry is guaranteed that SwitchPoint was not yet visible to any guard, so skipping it is safe.
> * Both detach paths ({{detachLive()}} and the new {{detachIfCurrent(sp)}}) deregister on successful detach, so all maintenance funnels through the existing allocation/retirement choke points; per-class invalidation needs no changes.
> * {{retireAllLoadedDomains()}} drains the registry: each entry is claimed via {{detachIfCurrent}}, and an entry is removed *only on a successful claim*. Removing on a failed claim would strand a concurrently-publishing SwitchPoint permanently invisible to all future drains (a correctness trap: pre-publish entries must survive the drain); failed-claim entries are transient and are cleaned up by their owner.
> * The GROOVY-12258 monotonic flag is replaced by {{registry-is-empty}}, which is strictly stronger: it also skips after all domains have retired, and re-arms rather than being one-shot. The classic-only skip is preserved.
> The drain's weakly consistent iteration can miss a SwitchPoint published mid-drain — the same window as the previous all-classes walk; sites linking concurrently read the current category state at link time, unchanged. One trade-off to note: the registry holds keys strongly, so a domain whose MetaClass has died stays pinned (one small SwitchPoint + invalidator) until any bulk event sweeps it.
> h3. Measurements
> JMH ({{-PbenchInclude=CategoryBench.categoryInLoop :perf:jmh}}, 2 forks x 5 iterations, JDK 21, same machine throughout):
> ||build||indy||classic||
> |Groovy 5 (5.1.x branch)|1489.8 ± 39.1 ms/op|163.2 ± 12.8 ms/op|
> |Groovy 6 pre-GROOVY-12191|1269.1 ± 45.5 ms/op|147.5 ± 12.0 ms/op|
> |master (post-GROOVY-12191)|2141.1 ± 97.8 ms/op|365.9 ± 18.5 ms/op|
> |+ GROOVY-12258|2141.1 ± 97.8 ms/op|59.9 ± 1.2 ms/op|
> |+ this change|1596.1 ± 57.1 ms/op|60.5 ± 1.1 ms/op|
> Indy improves 25% over master; classic keeps the GROOVY-12258 level. On this worst-case category-churn bench, indy remains ~26% behind pre-GROOVY-12191: the residual is the relink storm (scoped domains retire many per-MetaClass SwitchPoints where the old design retired one global one), not the walk. Closing that would need a further design change — e.g. a dedicated category SwitchPoint axis so category enter/leave stops retiring MetaClass domains — and is out of scope here.
> New unit coverage includes a get/detach/drain concurrency hammer asserting no live SwitchPoint is ever left unregistered, exactly-once claiming between owner detach and bulk drain, and CAS-loser cleanup. All existing indy/vmplugin and category runtime tests pass.



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