# HG changeset patch
# User lucy
# Date 1598453526 -7200
#      Wed Aug 26 16:52:06 2020 +0200
# Node ID 094f38a19ae3f062a400014762790de74eeecd0b
# Parent  420cb1ce9b7d82f70c1b9c94dbf7a5b6c68fccf7
8250635: MethodArityHistogram should use Compile_lock in favour of fancy checks
Reviewed-by: mdoerr, thartmann

diff --git a/src/hotspot/share/runtime/sharedRuntime.cpp b/src/hotspot/share/runtime/sharedRuntime.cpp
--- a/src/hotspot/share/runtime/sharedRuntime.cpp
+++ b/src/hotspot/share/runtime/sharedRuntime.cpp
@@ -2155,8 +2155,8 @@
   static int _max_size;                       // max. arg size seen
 
   static void add_method_to_histogram(nmethod* nm) {
-    if (CompiledMethod::nmethod_access_is_safe(nm)) {
-      Method* method = nm->method();
+    Method* method = (nm == NULL) ? NULL : nm->method();
+    if ((method != NULL) && nm->is_alive()) {
       ArgumentCount args(method->signature());
       int arity   = args.size() + (method->is_static() ? 0 : 1);
       int argsize = method->size_of_parameters();
@@ -2197,7 +2197,10 @@
 
  public:
   MethodArityHistogram() {
-    MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
+    // Take the Compile_lock to protect against changes in the CodeBlob structures
+    MutexLockerEx mu1(Compile_lock, Mutex::_no_safepoint_check_flag);
+    // Take the CodeCache_lock to protect against changes in the CodeHeap structure
+    MutexLockerEx mu2(CodeCache_lock, Mutex::_no_safepoint_check_flag);
     _max_arity = _max_size = 0;
     for (int i = 0; i < MAX_ARITY; i++) _arity_histogram[i] = _size_histogram[i] = 0;
     CodeCache::nmethods_do(add_method_to_histogram);