8313816: Accessing jmethodID might lead to spurious crashes

src/hotspot/share/oops/instanceKlass.cpp

@@ -587,15 +587,20 @@ void InstanceKlass::deallocate_contents(ClassLoaderData* loader_data) {
   // Also remove mirror from handles
   loader_data->remove_handle(_java_mirror);
 
-  // Need to take this class off the class loader data list.
-  loader_data->remove_class(this);
-
   // The array_klass for this class is created later, after error handling.
   // For class redefinition, we keep the original class so this scratch class
   // doesn't have an array class.  Either way, assert that there is nothing
   // to deallocate.
   assert(array_klasses() == nullptr, "array classes shouldn't be created for this class yet");
 
+  jmethodID* jmeths = methods_jmethod_ids_acquire();
+  if (jmeths != (jmethodID*)nullptr) {
+    size_t count = (size_t)jmeths[0];
+    for (size_t i = 1; i <= count; i++) {
+        Method::destroy_jmethod_id(class_loader_data(), jmeths[i]);
+    }
+  }
+
   // Release C heap allocated data that this points to, which includes
   // reference counting symbol names.
   // Can't release the constant pool or MethodData C heap data here because the constant

src/hotspot/share/oops/method.hpp

@@ -783,7 +783,9 @@ class Method : public Metadata {
   // (see AsyncGetCallTrace support for Forte Analyzer) and this
   // needs to be async-safe. No allocation should be done and
   // so handles are not used to avoid deadlock.
-  jmethodID find_jmethod_id_or_null()               { return method_holder()->jmethod_id_or_null(this); }
+  jmethodID find_jmethod_id_or_null()               {
+    return method_holder() != nullptr ? method_holder()->jmethod_id_or_null(this) : nullptr;
+  }
 
   // Support for inlining of intrinsic methods
   vmIntrinsicID intrinsic_id() const          { return (vmIntrinsicID) _intrinsic_id;           }