From 08db4b99622e488558dd7987c34f1c515fa30426 Mon Sep 17 00:00:00 2001 From: William Kemper Date: Fri, 15 Aug 2025 17:56:47 +0000 Subject: [PATCH] 8365571: GenShen: PLAB promotions may remain disabled for evacuation threads Reviewed-by: kdnilsen, ysr, shade --- .../gc/shenandoah/shenandoahConcurrentGC.cpp | 23 ++++--------------- .../share/gc/shenandoah/shenandoahHeap.cpp | 5 ++++ 2 files changed, 9 insertions(+), 19 deletions(-) diff --git a/src/hotspot/share/gc/shenandoah/shenandoahConcurrentGC.cpp b/src/hotspot/share/gc/shenandoah/shenandoahConcurrentGC.cpp index 81154aff9f0..d4c7ad5df50 100644 --- a/src/hotspot/share/gc/shenandoah/shenandoahConcurrentGC.cpp +++ b/src/hotspot/share/gc/shenandoah/shenandoahConcurrentGC.cpp @@ -823,7 +823,6 @@ bool ShenandoahConcurrentGC::has_in_place_promotions(ShenandoahHeap* heap) { return heap->mode()->is_generational() && heap->old_generation()->has_in_place_promotions(); } -template class ShenandoahConcurrentEvacThreadClosure : public ThreadClosure { private: OopClosure* const _oops; @@ -833,13 +832,9 @@ public: void do_thread(Thread* thread) override { JavaThread* const jt = JavaThread::cast(thread); StackWatermarkSet::finish_processing(jt, _oops, StackWatermarkKind::gc); - if (GENERATIONAL) { - ShenandoahThreadLocalData::enable_plab_promotions(thread); - } } }; -template class ShenandoahConcurrentEvacUpdateThreadTask : public WorkerTask { private: ShenandoahJavaThreadsIterator _java_threads; @@ -851,30 +846,20 @@ public: } void work(uint worker_id) override { - if (GENERATIONAL) { - Thread* worker_thread = Thread::current(); - ShenandoahThreadLocalData::enable_plab_promotions(worker_thread); - } - // ShenandoahEvacOOMScope has to be setup by ShenandoahContextEvacuateUpdateRootsClosure. // Otherwise, may deadlock with watermark lock ShenandoahContextEvacuateUpdateRootsClosure oops_cl; - ShenandoahConcurrentEvacThreadClosure thr_cl(&oops_cl); + ShenandoahConcurrentEvacThreadClosure thr_cl(&oops_cl); _java_threads.threads_do(&thr_cl, worker_id); } }; void ShenandoahConcurrentGC::op_thread_roots() { - ShenandoahHeap* const heap = ShenandoahHeap::heap(); + const ShenandoahHeap* const heap = ShenandoahHeap::heap(); assert(heap->is_evacuation_in_progress(), "Checked by caller"); ShenandoahGCWorkerPhase worker_phase(ShenandoahPhaseTimings::conc_thread_roots); - if (heap->mode()->is_generational()) { - ShenandoahConcurrentEvacUpdateThreadTask task(heap->workers()->active_workers()); - heap->workers()->run_task(&task); - } else { - ShenandoahConcurrentEvacUpdateThreadTask task(heap->workers()->active_workers()); - heap->workers()->run_task(&task); - } + ShenandoahConcurrentEvacUpdateThreadTask task(heap->workers()->active_workers()); + heap->workers()->run_task(&task); } void ShenandoahConcurrentGC::op_weak_refs() { diff --git a/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp b/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp index 2baf7e25cba..b90468501f6 100644 --- a/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp +++ b/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp @@ -1216,6 +1216,11 @@ public: // 1. We need to make the plab memory parsable by remembered-set scanning. // 2. We need to establish a trustworthy UpdateWaterMark value within each old-gen heap region ShenandoahGenerationalHeap::heap()->retire_plab(plab, thread); + + // Re-enable promotions for the next evacuation phase. + ShenandoahThreadLocalData::enable_plab_promotions(thread); + + // Reset the fill size for next evacuation phase. if (_resize && ShenandoahThreadLocalData::plab_size(thread) > 0) { ShenandoahThreadLocalData::set_plab_size(thread, 0); }