8278475: G1 dirty card refinement by Java threads may get unnecessarily paused

src/hotspot/share/gc/g1/g1DirtyCardQueue.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2022, 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
@@ -495,6 +495,14 @@ void G1DirtyCardQueueSet::handle_completed_buffer(BufferNode* new_node,
     return;
   }
 
+  // Don't try to process a buffer that will just get immediately paused.
+  // When going int a safepoint it's just a waste of effort.
+  // When coming out of a safepoint, Java threads may be running before the
+  // yield request (for non-Java threads) has been cleared.
+  if (SuspendibleThreadSet::should_yield()) {
+    return;
+  }
+
   // Only Java threads perform mutator refinement.
   if (!Thread::current()->is_Java_thread()) {
     return;