Performance Optimization for Script::Run()

[Jun Liang]

Hi All,

We are trying to replace a component (of our current product) with V8 engine. I am writing a V8 helper class in C++.

Init(): to initialize V8 engine and compile the given JavaScript.

Run(): to run the compiled script.

The Run() will be called more than 100,000,000 times. Could you give us some suggestions to optimize this part?

Thank you very much!!

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Persistent<Context, CopyablePersistentTraits<Context>> _context;

Persistent<Script, CopyablePersistentTraits<Script>> _script;

void Init(char *strJavaScript) 

{

strScript = strJavaScript;

this->isolate = Isolate::New();

isolate->Enter();

Isolate::Scope isolate_scope(this->isolate);

HandleScope handle_scope(this->isolate);

Handle<ObjectTemplate> templ = ObjectTemplate::New(this->isolate);

templ->SetAccessor(v8_str("inputStr"), getStringValue, setStringValue, External::New(this->isolate, &inputStr));

templ->SetAccessor(v8_str("inputNum"), getIntValue, setIntValue, External::New(this->isolate, &inputNum));

templ->SetAccessor(v8_str("outputStr"), getStringValue, setStringValue, External::New(this->isolate, &outputStr));

templ->SetAccessor(v8_str("outputNum"), getIntValue, setIntValue, External::New(this->isolate, &outputNum));

Handle<Context> context = Context::New(isolate, NULL, templ);

_context = Persistent<Context, CopyablePersistentTraits<Context>>(isolate, context);

Context::Scope context_scope(context);

// Create a string containing the JavaScript source code.

Handle<String> source = String::NewFromUtf8(isolate, strScript);

// Compile the given JavaScript

Handle<Script> script = Script::Compile(source);

_script = Persistent<Script, CopyablePersistentTraits<Script>>(isolate, script);

}

void Run() 

{

HandleScope scope(Isolate::GetCurrent());

Context::Scope context_scope(Local<Context>::New(Isolate::GetCurrent(), this->_context));

Local<Value> result = Local<Script>::New(Isolate::GetCurrent(), this->_script)->Run();

}

[Gregory Hlavac]

In my usage of V8 to run something repetitively, I had it run once and execute a callback within the script to create a concrete object in the engine that would be executed every update loop cycle, and that object kept handles to callbacks into script-land to handle that sort of thing.

The gist is, don't constantly run it over and over and over again.