Avoid possibly lengthy destruction of wasm instances on shutdown

libraries/chain/include/eosio/chain/wasm_interface.hpp

@@ -59,6 +59,9 @@ namespace eosio { namespace chain {
          wasm_interface(vm_type vm);
          ~wasm_interface();
 
+         //call before dtor to skip what can be minutes of dtor overhead with some runtimes; can cause leaks
+         void indicate_shutting_down();
+
          //validates code -- does a WASM validation pass and checks the wasm against EOSIO specific constraints
          static void validate(const controller& control, const bytes& code);
 

libraries/chain/include/eosio/chain/wasm_interface_private.hpp

@@ -32,6 +32,11 @@ namespace eosio { namespace chain {
             EOS_THROW(wasm_exception, "wasm_interface_impl fall through");
       }
 
+      ~wasm_interface_impl() {
+         if(is_shutting_down)
+            std::for_each(instantiation_cache.begin(), instantiation_cache.end(), [](auto& i) {i.second.release();});
+      }
+
       std::vector<uint8_t> parse_initial_memory(const Module& module) {
          std::vector<uint8_t> mem_image;
 
@@ -89,6 +94,7 @@ namespace eosio { namespace chain {
          return it->second;
       }
 
+      bool is_shutting_down = false;
       std::unique_ptr<wasm_runtime_interface> runtime_interface;
       map<digest_type, std::unique_ptr<wasm_instantiated_module_interface>> instantiation_cache;
    };

libraries/chain/wasm_interface.cpp

@@ -54,6 +54,10 @@ namespace eosio { namespace chain {
       //Hard: Kick off instantiation in a separate thread at this location
 	 }
 
+   void wasm_interface::indicate_shutting_down() {
+      my->is_shutting_down = true;
+   }
+
    void wasm_interface::apply( const digest_type& code_id, const shared_string& code, apply_context& context ) {
       my->get_instantiated_module(code_id, code, context.trx_context)->apply(context);
    }

plugins/chain_plugin/chain_plugin.cpp

@@ -770,6 +770,8 @@ void chain_plugin::plugin_shutdown() {
    my->irreversible_block_connection.reset();
    my->accepted_transaction_connection.reset();
    my->applied_transaction_connection.reset();
+   if(app().is_quiting())
+      my->chain->get_wasm_interface().indicate_shutting_down();
    my->chain.reset();
 }