From 5f8cb30fc0296a2b487edf9dee63e810f4861e8e Mon Sep 17 00:00:00 2001 From: Thomas Schatzl Date: Tue, 20 Jan 2026 18:16:39 +0000 Subject: [PATCH] 8375626: G1: Convert G1CollectionSetChooser to use Atomic Reviewed-by: kbarrett, shade --- .../share/gc/g1/g1CollectionSetChooser.cpp | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/src/hotspot/share/gc/g1/g1CollectionSetChooser.cpp b/src/hotspot/share/gc/g1/g1CollectionSetChooser.cpp index 954ca40a77f..d9496410c12 100644 --- a/src/hotspot/share/gc/g1/g1CollectionSetChooser.cpp +++ b/src/hotspot/share/gc/g1/g1CollectionSetChooser.cpp @@ -1,5 +1,5 @@ /* - * Copyright (c) 2001, 2025, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2001, 2026, 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 @@ -27,7 +27,7 @@ #include "gc/g1/g1CollectionSetChooser.hpp" #include "gc/g1/g1HeapRegionRemSet.inline.hpp" #include "gc/shared/space.hpp" -#include "runtime/atomicAccess.hpp" +#include "runtime/atomic.hpp" #include "utilities/quickSort.hpp" // Determine collection set candidates (from marking): For all regions determine @@ -50,7 +50,7 @@ class G1BuildCandidateRegionsTask : public WorkerTask { G1HeapRegion** _data; - uint volatile _cur_claim_idx; + Atomic _cur_claim_idx; static int compare_region_gc_efficiency(G1HeapRegion** rr1, G1HeapRegion** rr2) { G1HeapRegion* r1 = *rr1; @@ -105,7 +105,7 @@ class G1BuildCandidateRegionsTask : public WorkerTask { // Claim a new chunk, returning its bounds [from, to[. void claim_chunk(uint& from, uint& to) { - uint result = AtomicAccess::add(&_cur_claim_idx, _chunk_size); + uint result = _cur_claim_idx.add_then_fetch(_chunk_size); assert(_max_size > result - 1, "Array too small, is %u should be %u with chunk size %u.", _max_size, result, _chunk_size); @@ -121,14 +121,15 @@ class G1BuildCandidateRegionsTask : public WorkerTask { } void sort_by_gc_efficiency() { - if (_cur_claim_idx == 0) { + uint length = _cur_claim_idx.load_relaxed(); + if (length == 0) { return; } - for (uint i = _cur_claim_idx; i < _max_size; i++) { + for (uint i = length; i < _max_size; i++) { assert(_data[i] == nullptr, "must be"); } - qsort(_data, _cur_claim_idx, sizeof(_data[0]), (_sort_Fn)compare_region_gc_efficiency); - for (uint i = _cur_claim_idx; i < _max_size; i++) { + qsort(_data, length, sizeof(_data[0]), (_sort_Fn)compare_region_gc_efficiency); + for (uint i = length; i < _max_size; i++) { assert(_data[i] == nullptr, "must be"); } }