From b59610dc5dda43b36922fb63856afb08e630f6bc Mon Sep 17 00:00:00 2001 From: Thomas Schatzl Date: Wed, 6 May 2026 16:07:25 +0200 Subject: [PATCH 1/2] 8383856 Hi all, please review this change of the default collector, making G1 the only default ever selected by ergonomics. If G1 is not compiled in, the orginal logic to first try parallel and then serial has been maintained (which also necessitates keeping os::is_server_class_machine()). Testing: gha, tier1-3 Thanks, Thomas --- src/hotspot/share/gc/shared/gcConfig.cpp | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/src/hotspot/share/gc/shared/gcConfig.cpp b/src/hotspot/share/gc/shared/gcConfig.cpp index 402bd0caacddc..b62c745e50952 100644 --- a/src/hotspot/share/gc/shared/gcConfig.cpp +++ b/src/hotspot/share/gc/shared/gcConfig.cpp @@ -95,10 +95,11 @@ void GCConfig::fail_if_non_included_gc_is_selected() { } void GCConfig::select_gc_ergonomically() { - if (os::is_server_class_machine()) { #if INCLUDE_G1GC - FLAG_SET_ERGO_IF_DEFAULT(UseG1GC, true); -#elif INCLUDE_PARALLELGC + FLAG_SET_ERGO_IF_DEFAULT(UseG1GC, true); +#else + if (os::is_server_class_machine()) { +#if INCLUDE_PARALLELGC FLAG_SET_ERGO_IF_DEFAULT(UseParallelGC, true); #elif INCLUDE_SERIALGC FLAG_SET_ERGO_IF_DEFAULT(UseSerialGC, true); @@ -108,6 +109,7 @@ void GCConfig::select_gc_ergonomically() { FLAG_SET_ERGO_IF_DEFAULT(UseSerialGC, true); #endif } +#endif } bool GCConfig::is_no_gc_selected() { From 9694279348562a7bea1a4339727291f70a4b6787 Mon Sep 17 00:00:00 2001 From: Thomas Schatzl Date: Thu, 7 May 2026 14:59:39 +0200 Subject: [PATCH 2/2] * update copyright, phuebner review --- src/hotspot/share/gc/shared/gcConfig.cpp | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/hotspot/share/gc/shared/gcConfig.cpp b/src/hotspot/share/gc/shared/gcConfig.cpp index b62c745e50952..c31bce353541d 100644 --- a/src/hotspot/share/gc/shared/gcConfig.cpp +++ b/src/hotspot/share/gc/shared/gcConfig.cpp @@ -1,5 +1,5 @@ /* - * Copyright (c) 2018, 2025, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2018, 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