From d609551899e3a123fb38855cb25b17fe5b7674e7 Mon Sep 17 00:00:00 2001
From: Evgeny Astigeevich <eastig@amazon.com>
Date: Wed, 10 Jun 2026 14:06:14 +0000
Subject: [PATCH] HCC sample_all_java_threads finishes if contention with JFR
 is detected

---
 src/hotspot/share/runtime/hotCodeSampler.cpp | 18 +++++++++++++++++-
 src/hotspot/share/runtime/hotCodeSampler.hpp | 13 -------------
 2 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/src/hotspot/share/runtime/hotCodeSampler.cpp b/src/hotspot/share/runtime/hotCodeSampler.cpp
index 3e0b5022fed..0bcef40e2c7 100644
--- a/src/hotspot/share/runtime/hotCodeSampler.cpp
+++ b/src/hotspot/share/runtime/hotCodeSampler.cpp
@@ -29,6 +29,12 @@
 #include "runtime/hotCodeSampler.hpp"
 #include "runtime/javaThread.inline.hpp"
 
+#if INCLUDE_JFR
+#include "jfr/utilities/jfrTryLock.hpp"
+
+using SuspendedThreadTaskTryLock = JfrMutexTryLock;
+#endif
+
 void ThreadSampler::sample_all_java_threads() {
   // Collect samples for each JavaThread
   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) {
@@ -39,7 +45,17 @@ void ThreadSampler::sample_all_java_threads() {
     }
 
     GetPCTask task(jt);
-    task.request_pc();
+    {
+#if INCLUDE_JFR
+      SuspendedThreadTaskTryLock try_lock(SuspendedThreadTask_lock);
+      if (!try_lock.acquired()) {
+        log_debug(hotcode)("Suspend lock held by JFR sampler; ending sampling pass, will retry next round");
+        return;
+      }
+#endif
+      task.run();
+    }
+
     address pc = task.pc();
     if (pc == nullptr) {
       continue;
diff --git a/src/hotspot/share/runtime/hotCodeSampler.hpp b/src/hotspot/share/runtime/hotCodeSampler.hpp
index 2a96f0ded28..d61cac791e1 100644
--- a/src/hotspot/share/runtime/hotCodeSampler.hpp
+++ b/src/hotspot/share/runtime/hotCodeSampler.hpp
@@ -27,8 +27,6 @@
 #define SHARE_RUNTIME_HOTCODESAMPLER_HPP
 
 #include "runtime/javaThread.hpp"
-#include "runtime/mutex.hpp"
-#include "runtime/mutexLocker.hpp"
 #include "runtime/suspendedThreadTask.hpp"
 #include "runtime/threadSMR.hpp"
 #include "utilities/pair.hpp"
@@ -77,17 +75,6 @@ class GetPCTask : public SuspendedThreadTask {
  public:
   GetPCTask(JavaThread* thread) : SuspendedThreadTask(thread), _pc(nullptr) {}
 
-  void request_pc() {
-#if INCLUDE_JFR
-    if (SuspendedThreadTask_lock->try_lock()) {
-      run();
-      SuspendedThreadTask_lock->unlock();
-    }
-#else
-    run();
-#endif
-  }
-
   address pc() const {
     return _pc;
   }