From 002c538bc03f55fa600f331a66242ee8575919dc Mon Sep 17 00:00:00 2001 From: Zhengyu Gu Date: Tue, 19 Oct 2021 14:14:23 +0000 Subject: [PATCH] 8275287: Relax memory ordering constraints on updating instance class and array class counters Reviewed-by: dholmes, rkennke --- .../classfile/classLoaderDataGraph.inline.hpp | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/src/hotspot/share/classfile/classLoaderDataGraph.inline.hpp b/src/hotspot/share/classfile/classLoaderDataGraph.inline.hpp index 9e93c4ef926..e5b51ac277c 100644 --- a/src/hotspot/share/classfile/classLoaderDataGraph.inline.hpp +++ b/src/hotspot/share/classfile/classLoaderDataGraph.inline.hpp @@ -1,5 +1,5 @@ /* - * Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2018, 2021, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it @@ -30,6 +30,7 @@ #include "classfile/javaClasses.hpp" #include "oops/oop.inline.hpp" #include "runtime/atomic.hpp" +#include "runtime/orderAccess.hpp" inline ClassLoaderData *ClassLoaderDataGraph::find_or_create(Handle loader) { guarantee(loader() != NULL && oopDesc::is_oop(loader()), "Loader must be oop"); @@ -43,29 +44,29 @@ inline ClassLoaderData *ClassLoaderDataGraph::find_or_create(Handle loader) { } size_t ClassLoaderDataGraph::num_instance_classes() { - return _num_instance_classes; + return Atomic::load(&_num_instance_classes); } size_t ClassLoaderDataGraph::num_array_classes() { - return _num_array_classes; + return Atomic::load(&_num_array_classes); } void ClassLoaderDataGraph::inc_instance_classes(size_t count) { - Atomic::add(&_num_instance_classes, count); + Atomic::add(&_num_instance_classes, count, memory_order_relaxed); } void ClassLoaderDataGraph::dec_instance_classes(size_t count) { - assert(count <= _num_instance_classes, "Sanity"); - Atomic::sub(&_num_instance_classes, count); + size_t old_count = Atomic::fetch_and_add(&_num_instance_classes, -count, memory_order_relaxed); + assert(old_count >= count, "Sanity"); } void ClassLoaderDataGraph::inc_array_classes(size_t count) { - Atomic::add(&_num_array_classes, count); + Atomic::add(&_num_array_classes, count, memory_order_relaxed); } void ClassLoaderDataGraph::dec_array_classes(size_t count) { - assert(count <= _num_array_classes, "Sanity"); - Atomic::sub(&_num_array_classes, count); + size_t old_count = Atomic::fetch_and_add(&_num_array_classes, -count, memory_order_relaxed); + assert(old_count >= count, "Sanity"); } bool ClassLoaderDataGraph::should_clean_metaspaces_and_reset() {