On Wed, Oct 15, 2014 at 2:04 AM, Grant Hutchins <ghutch...@pivotal.io> wrote: > I have a Node ObjectWrap subclass object that handles a uv_async_send from a > thread I don't control (from a key-value store library I'm using that can > trigger an event at any time). I would like to make sure that if > uv_async_send is triggered from this other thread, I can call Ref() on my > ObjectWrap so that its v8 object doesn't get GC'ed before the async fires on > the main loop. > > So far the only way I've gotten things to work is to call Ref() in the > constructor of the ObjectWrap, but that means that it never gets GC'ed. I'd > prefer that it get GC'ed as normal, except when an event has come in and > triggered a uv_async_send that hasn't yet been processed on the v8 main > loop. > > It seems that I keep running into a race condition between somehow getting > the main loop to call Ref() and hoping the GC doesn't fire before that and > delete the v8 object and thus my ObjectWrap. Am I correct in assuming that > Ref() must be called from the main loop?
That's correct, you can only call ObjectWrap::Ref() from the main thread. It's in theory possible to create a thread-safe ObjectWrap class that acquires a v8::Locker but that won't help with the race condition you mention: the object can still be garbage-collected before the call to ObjectWrap::Ref(). You can make the object weak with ObjectWrap::MakeWeak(). ObjectWrap::MakeWeak() invoke the destructor of your class when the object is garbage-collected. Please note that libuv handles must be explicitly closed with uv_close() and that uv_close() is asynchronous: you cannot call it from your destructor on an embedded uv_async_t handle because the lifetime of the handle needs to exceed that of the embedding object. New the uv_async_t in your constructor and delete it in the OnClose callback. -- Job board: http://jobs.nodejs.org/ New group rules: https://gist.github.com/othiym23/9886289#file-moderation-policy-md Old group rules: https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines --- You received this message because you are subscribed to the Google Groups "nodejs" group. To unsubscribe from this group and stop receiving emails from it, send an email to nodejs+unsubscr...@googlegroups.com. To post to this group, send email to nodejs@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/nodejs/CAHQurc-1zoONgGnoOjHSZEMVf0bYryGj85eBu6x9YV%2BQQ88q9Q%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
