On Tue, Nov 17, 2015 at 5:29 AM, Eric Yen <e...@ericyen.com> wrote: > Hi, > > I was wondering could point me in the in the right direction. > I have a C library running in a thread #1. When works arrive in thread #1, > work is queued on to a Queue, and the thread wakes up thread #2 through > uv_async_send, which wakes up the libuv event loop. Thread #2 gets the work > from the Queue and invokes v8. > > A lot of the work enqueued by thread #1 is a small buffer of ~64kb that > needs to be duplicated before it is enqueued. This memory duplication can be > slow because of malloc. From my understanding of nodejs, small buffers in > nodejs are allocated from a managed memory pool, avoiding the need to call > malloc frequently. > > What I would like to do is have thread #1 directly create a node::Buffer / > Nan;:Buffer, add the work to Queue, and have the uv event loop woken up. > > So here's my questions. > 1) How can I create an object in thread #1 that will persist in to the > second thread? > One option would be to create a Persistent object and then clearing it once > it's finished. > Second option, which I'm not sure would work, and I wouldn't know why it > won't work, would be to create the buffer in thread #1 and Escaping it with > an EscapableHandlescope.
You can create the Buffer object upfront in the main thread and wrap it in a strong Persistent handle to prevent the GC from reclaiming it. You will need to record the pointer to the Buffer's memory separately because you're not allowed to call node::Buffer::Data() on a different thread. Alternatively, you can malloc() the memory on the worker thread and turn it into a zero-copy Buffer on the main thread. Put anything involving node.js or V8 on a different thread out of your head, it won't be reliable (in the crash-and-eat-your-data-not-reliable sense.) > 2) Is it even worth it? > My understanding is that I would have to create a v8::Locker in thread #1 to > ensure thread safety. > Would creating and acquiring the v8::Locker be much slower than just > malloc'ing a small buffer? Using a v8::Locker won't help because the main thread doesn't release the isolate when it goes to sleep. Other threads won't be able to claim it, they'll just wait forever. -- 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_nVk6Pon6Ff%3Dx6nqRnUc557AkXiGB3SQHVjvu6Ezt3Sw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
