8258652: Assert in JvmtiThreadState::cur_stack_depth() can noticeably slow down debugging single stepping

Reviewed-by: sspitsyn, dholmes, amenkov

Author: plummercj

src/hotspot/share/prims/jvmtiThreadState.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2021, 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
@@ -282,9 +282,14 @@ int JvmtiThreadState::cur_stack_depth() {
   if (!is_interp_only_mode() || _cur_stack_depth == UNKNOWN_STACK_DEPTH) {
     _cur_stack_depth = count_frames();
   } else {
-    // heavy weight assert
-    assert(_cur_stack_depth == count_frames(),
-           "cur_stack_depth out of sync");
+#ifdef ASSERT
+    if (EnableJVMTIStackDepthAsserts) {
+      // heavy weight assert
+      jint num_frames = count_frames();
+      assert(_cur_stack_depth == num_frames, "cur_stack_depth out of sync _cur_stack_depth: %d num_frames: %d",
+             _cur_stack_depth, num_frames);
+    }
+#endif
   }
   return _cur_stack_depth;
 }

src/hotspot/share/runtime/globals.hpp

@@ -1805,6 +1805,9 @@ const intx ObjectAlignmentInBytes = 8;
   notproduct(bool, UseDebuggerErgo2, false,                                 \
           "Debugging Only: Limit the number of spawned JVM threads")        \
                                                                             \
+  notproduct(bool, EnableJVMTIStackDepthAsserts, true,                      \
+          "Enable JVMTI asserts related to stack depth checks")             \
+                                                                            \
   /* flags for performance data collection */                               \
                                                                             \
   product(bool, UsePerfData, true,                                          \