From 673cd6ed0c4ebbb301346e8e251d1674f363c0d8 Mon Sep 17 00:00:00 2001 From: William Kemper Date: Fri, 30 Jan 2026 16:54:47 +0000 Subject: [PATCH] 8374449: Shenandoah: Leaf locks used by Shenandoah need lower ranks Reviewed-by: ysr --- .../share/gc/shenandoah/shenandoahControlThread.cpp | 2 +- src/hotspot/share/gc/shenandoah/shenandoahController.hpp | 7 +++++-- .../gc/shenandoah/shenandoahGenerationalControlThread.cpp | 2 +- 3 files changed, 7 insertions(+), 4 deletions(-) diff --git a/src/hotspot/share/gc/shenandoah/shenandoahControlThread.cpp b/src/hotspot/share/gc/shenandoah/shenandoahControlThread.cpp index 590e7831f07..bc11659c5e5 100644 --- a/src/hotspot/share/gc/shenandoah/shenandoahControlThread.cpp +++ b/src/hotspot/share/gc/shenandoah/shenandoahControlThread.cpp @@ -44,7 +44,7 @@ ShenandoahControlThread::ShenandoahControlThread() : ShenandoahController(), _requested_gc_cause(GCCause::_no_gc), _degen_point(ShenandoahGC::_degenerated_outside_cycle), - _control_lock(Mutex::nosafepoint - 2, "ShenandoahGCRequest_lock", true) { + _control_lock(CONTROL_LOCK_RANK, "ShenandoahControl_lock", true) { set_name("Shenandoah Control Thread"); create_and_start(); } diff --git a/src/hotspot/share/gc/shenandoah/shenandoahController.hpp b/src/hotspot/share/gc/shenandoah/shenandoahController.hpp index a6a699fac3b..b8ff4df4771 100644 --- a/src/hotspot/share/gc/shenandoah/shenandoahController.hpp +++ b/src/hotspot/share/gc/shenandoah/shenandoahController.hpp @@ -42,6 +42,9 @@ private: shenandoah_padding(1); protected: + const Mutex::Rank WAITERS_LOCK_RANK = Mutex::safepoint - 5; + const Mutex::Rank CONTROL_LOCK_RANK = Mutex::nosafepoint - 2; + // While we could have a single lock for these, it may risk unblocking // GC waiters when alloc failure GC cycle finishes. We want instead // to make complete explicit cycle for demanding customers. @@ -54,8 +57,8 @@ protected: public: ShenandoahController(): _gc_id(0), - _alloc_failure_waiters_lock(Mutex::safepoint-2, "ShenandoahAllocFailureGC_lock", true), - _gc_waiters_lock(Mutex::safepoint-2, "ShenandoahRequestedGC_lock", true) + _alloc_failure_waiters_lock(WAITERS_LOCK_RANK, "ShenandoahAllocFailureWaiters_lock", true), + _gc_waiters_lock(WAITERS_LOCK_RANK, "ShenandoahGCWaiters_lock", true) { } // Request a collection cycle. This handles "explicit" gc requests diff --git a/src/hotspot/share/gc/shenandoah/shenandoahGenerationalControlThread.cpp b/src/hotspot/share/gc/shenandoah/shenandoahGenerationalControlThread.cpp index 018b4898a19..3b57190cc75 100644 --- a/src/hotspot/share/gc/shenandoah/shenandoahGenerationalControlThread.cpp +++ b/src/hotspot/share/gc/shenandoah/shenandoahGenerationalControlThread.cpp @@ -47,7 +47,7 @@ #include "utilities/events.hpp" ShenandoahGenerationalControlThread::ShenandoahGenerationalControlThread() : - _control_lock(Mutex::nosafepoint - 2, "ShenandoahGCRequest_lock", true), + _control_lock(CONTROL_LOCK_RANK, "ShenandoahGCRequest_lock", true), _requested_gc_cause(GCCause::_no_gc), _requested_generation(nullptr), _gc_mode(none),